sched/wake_q: Clarify queue reinit comment

[linux.git] / include / linux / sched.h

#ifndef _LINUX_SCHED_H
#define _LINUX_SCHED_H

#include <uapi/linux/sched.h>

#include <linux/sched/prio.h>


struct sched_param {
        int sched_priority;
};

#include <asm/param.h>  /* for HZ */

#include <linux/capability.h>
#include <linux/threads.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/timex.h>
#include <linux/jiffies.h>
#include <linux/plist.h>
#include <linux/rbtree.h>
#include <linux/thread_info.h>
#include <linux/cpumask.h>
#include <linux/errno.h>
#include <linux/nodemask.h>
#include <linux/mm_types.h>
#include <linux/preempt.h>

#include <asm/page.h>
#include <asm/ptrace.h>
#include <linux/cputime.h>

#include <linux/smp.h>
#include <linux/sem.h>
#include <linux/shm.h>
#include <linux/signal.h>
#include <linux/compiler.h>
#include <linux/completion.h>
#include <linux/pid.h>
#include <linux/percpu.h>
#include <linux/topology.h>
#include <linux/seccomp.h>
#include <linux/rcupdate.h>
#include <linux/rculist.h>
#include <linux/rtmutex.h>

#include <linux/time.h>
#include <linux/param.h>
#include <linux/resource.h>
#include <linux/timer.h>
#include <linux/hrtimer.h>
#include <linux/kcov.h>
#include <linux/task_io_accounting.h>
#include <linux/latencytop.h>
#include <linux/cred.h>
#include <linux/llist.h>
#include <linux/uidgid.h>
#include <linux/gfp.h>
#include <linux/magic.h>
#include <linux/cgroup-defs.h>

#include <asm/processor.h>

#define SCHED_ATTR_SIZE_VER0    48      /* sizeof first published struct */

/*
 * Extended scheduling parameters data structure.
 *
 * This is needed because the original struct sched_param can not be
 * altered without introducing ABI issues with legacy applications
 * (e.g., in sched_getparam()).
 *
 * However, the possibility of specifying more than just a priority for
 * the tasks may be useful for a wide variety of application fields, e.g.,
 * multimedia, streaming, automation and control, and many others.
 *
 * This variant (sched_attr) is meant at describing a so-called
 * sporadic time-constrained task. In such model a task is specified by:
 *  - the activation period or minimum instance inter-arrival time;
 *  - the maximum (or average, depending on the actual scheduling
 *    discipline) computation time of all instances, a.k.a. runtime;
 *  - the deadline (relative to the actual activation time) of each
 *    instance.
 * Very briefly, a periodic (sporadic) task asks for the execution of
 * some specific computation --which is typically called an instance--
 * (at most) every period. Moreover, each instance typically lasts no more
 * than the runtime and must be completed by time instant t equal to
 * the instance activation time + the deadline.
 *
 * This is reflected by the actual fields of the sched_attr structure:
 *
 *  @size               size of the structure, for fwd/bwd compat.
 *
 *  @sched_policy       task's scheduling policy
 *  @sched_flags        for customizing the scheduler behaviour
 *  @sched_nice         task's nice value      (SCHED_NORMAL/BATCH)
 *  @sched_priority     task's static priority (SCHED_FIFO/RR)
 *  @sched_deadline     representative of the task's deadline
 *  @sched_runtime      representative of the task's runtime
 *  @sched_period       representative of the task's period
 *
 * Given this task model, there are a multiplicity of scheduling algorithms
 * and policies, that can be used to ensure all the tasks will make their
 * timing constraints.
 *
 * As of now, the SCHED_DEADLINE policy (sched_dl scheduling class) is the
 * only user of this new interface. More information about the algorithm
 * available in the scheduling class file or in Documentation/.
 */
struct sched_attr {
        u32 size;

        u32 sched_policy;
        u64 sched_flags;

        /* SCHED_NORMAL, SCHED_BATCH */
        s32 sched_nice;

        /* SCHED_FIFO, SCHED_RR */
        u32 sched_priority;

        /* SCHED_DEADLINE */
        u64 sched_runtime;
        u64 sched_deadline;
        u64 sched_period;
};

struct futex_pi_state;
struct robust_list_head;
struct bio_list;
struct fs_struct;
struct perf_event_context;
struct blk_plug;
struct filename;
struct nameidata;

#define VMACACHE_BITS 2
#define VMACACHE_SIZE (1U << VMACACHE_BITS)
#define VMACACHE_MASK (VMACACHE_SIZE - 1)

/*
 * These are the constant used to fake the fixed-point load-average
 * counting. Some notes:
 *  - 11 bit fractions expand to 22 bits by the multiplies: this gives
 *    a load-average precision of 10 bits integer + 11 bits fractional
 *  - if you want to count load-averages more often, you need more
 *    precision, or rounding will get you. With 2-second counting freq,
 *    the EXP_n values would be 1981, 2034 and 2043 if still using only
 *    11 bit fractions.
 */
extern unsigned long avenrun[];         /* Load averages */
extern void get_avenrun(unsigned long *loads, unsigned long offset, int shift);

#define FSHIFT          11              /* nr of bits of precision */
#define FIXED_1         (1<<FSHIFT)     /* 1.0 as fixed-point */
#define LOAD_FREQ       (5*HZ+1)        /* 5 sec intervals */
#define EXP_1           1884            /* 1/exp(5sec/1min) as fixed-point */
#define EXP_5           2014            /* 1/exp(5sec/5min) */
#define EXP_15          2037            /* 1/exp(5sec/15min) */

#define CALC_LOAD(load,exp,n) \
        load *= exp; \
        load += n*(FIXED_1-exp); \
        load >>= FSHIFT;

extern unsigned long total_forks;
extern int nr_threads;
DECLARE_PER_CPU(unsigned long, process_counts);
extern int nr_processes(void);
extern unsigned long nr_running(void);
extern bool single_task_running(void);
extern unsigned long nr_iowait(void);
extern unsigned long nr_iowait_cpu(int cpu);
extern void get_iowait_load(unsigned long *nr_waiters, unsigned long *load);

extern void calc_global_load(unsigned long ticks);

#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
extern void cpu_load_update_nohz_start(void);
extern void cpu_load_update_nohz_stop(void);
#else
static inline void cpu_load_update_nohz_start(void) { }
static inline void cpu_load_update_nohz_stop(void) { }
#endif

extern void dump_cpu_task(int cpu);

struct seq_file;
struct cfs_rq;
struct task_group;
#ifdef CONFIG_SCHED_DEBUG
extern void proc_sched_show_task(struct task_struct *p, struct seq_file *m);
extern void proc_sched_set_task(struct task_struct *p);
#endif

/*
 * Task state bitmask. NOTE! These bits are also
 * encoded in fs/proc/array.c: get_task_state().
 *
 * We have two separate sets of flags: task->state
 * is about runnability, while task->exit_state are
 * about the task exiting. Confusing, but this way
 * modifying one set can't modify the other one by
 * mistake.
 */
#define TASK_RUNNING            0
#define TASK_INTERRUPTIBLE      1
#define TASK_UNINTERRUPTIBLE    2
#define __TASK_STOPPED          4
#define __TASK_TRACED           8
/* in tsk->exit_state */
#define EXIT_DEAD               16
#define EXIT_ZOMBIE             32
#define EXIT_TRACE              (EXIT_ZOMBIE | EXIT_DEAD)
/* in tsk->state again */
#define TASK_DEAD               64
#define TASK_WAKEKILL           128
#define TASK_WAKING             256
#define TASK_PARKED             512
#define TASK_NOLOAD             1024
#define TASK_NEW                2048
#define TASK_STATE_MAX          4096

#define TASK_STATE_TO_CHAR_STR "RSDTtXZxKWPNn"

extern char ___assert_task_state[1 - 2*!!(
                sizeof(TASK_STATE_TO_CHAR_STR)-1 != ilog2(TASK_STATE_MAX)+1)];

/* Convenience macros for the sake of set_current_state */
#define TASK_KILLABLE           (TASK_WAKEKILL | TASK_UNINTERRUPTIBLE)
#define TASK_STOPPED            (TASK_WAKEKILL | __TASK_STOPPED)
#define TASK_TRACED             (TASK_WAKEKILL | __TASK_TRACED)

#define TASK_IDLE               (TASK_UNINTERRUPTIBLE | TASK_NOLOAD)

/* Convenience macros for the sake of wake_up */
#define TASK_NORMAL             (TASK_INTERRUPTIBLE | TASK_UNINTERRUPTIBLE)
#define TASK_ALL                (TASK_NORMAL | __TASK_STOPPED | __TASK_TRACED)

/* get_task_state() */
#define TASK_REPORT             (TASK_RUNNING | TASK_INTERRUPTIBLE | \
                                 TASK_UNINTERRUPTIBLE | __TASK_STOPPED | \
                                 __TASK_TRACED | EXIT_ZOMBIE | EXIT_DEAD)

#define task_is_traced(task)    ((task->state & __TASK_TRACED) != 0)
#define task_is_stopped(task)   ((task->state & __TASK_STOPPED) != 0)
#define task_is_stopped_or_traced(task) \
                        ((task->state & (__TASK_STOPPED | __TASK_TRACED)) != 0)
#define task_contributes_to_load(task)  \
                                ((task->state & TASK_UNINTERRUPTIBLE) != 0 && \
                                 (task->flags & PF_FROZEN) == 0 && \
                                 (task->state & TASK_NOLOAD) == 0)

#ifdef CONFIG_DEBUG_ATOMIC_SLEEP

#define __set_current_state(state_value)                        \
        do {                                                    \
                current->task_state_change = _THIS_IP_;         \
                current->state = (state_value);                 \
        } while (0)
#define set_current_state(state_value)                          \
        do {                                                    \
                current->task_state_change = _THIS_IP_;         \
                smp_store_mb(current->state, (state_value));    \
        } while (0)

#else
/*
 * set_current_state() includes a barrier so that the write of current->state
 * is correctly serialised wrt the caller's subsequent test of whether to
 * actually sleep:
 *
 *   for (;;) {
 *      set_current_state(TASK_UNINTERRUPTIBLE);
 *      if (!need_sleep)
 *              break;
 *
 *      schedule();
 *   }
 *   __set_current_state(TASK_RUNNING);
 *
 * If the caller does not need such serialisation (because, for instance, the
 * condition test and condition change and wakeup are under the same lock) then
 * use __set_current_state().
 *
 * The above is typically ordered against the wakeup, which does:
 *
 *      need_sleep = false;
 *      wake_up_state(p, TASK_UNINTERRUPTIBLE);
 *
 * Where wake_up_state() (and all other wakeup primitives) imply enough
 * barriers to order the store of the variable against wakeup.
 *
 * Wakeup will do: if (@state & p->state) p->state = TASK_RUNNING, that is,
 * once it observes the TASK_UNINTERRUPTIBLE store the waking CPU can issue a
 * TASK_RUNNING store which can collide with __set_current_state(TASK_RUNNING).
 *
 * This is obviously fine, since they both store the exact same value.
 *
 * Also see the comments of try_to_wake_up().
 */
#define __set_current_state(state_value)                \
        do { current->state = (state_value); } while (0)
#define set_current_state(state_value)                  \
        smp_store_mb(current->state, (state_value))

#endif

/* Task command name length */
#define TASK_COMM_LEN 16

#include <linux/spinlock.h>

/*
 * This serializes "schedule()" and also protects
 * the run-queue from deletions/modifications (but
 * _adding_ to the beginning of the run-queue has
 * a separate lock).
 */
extern rwlock_t tasklist_lock;
extern spinlock_t mmlist_lock;

struct task_struct;

#ifdef CONFIG_PROVE_RCU
extern int lockdep_tasklist_lock_is_held(void);
#endif /* #ifdef CONFIG_PROVE_RCU */

extern void sched_init(void);
extern void sched_init_smp(void);
extern asmlinkage void schedule_tail(struct task_struct *prev);
extern void init_idle(struct task_struct *idle, int cpu);
extern void init_idle_bootup_task(struct task_struct *idle);

extern cpumask_var_t cpu_isolated_map;

extern int runqueue_is_locked(int cpu);

#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
extern void nohz_balance_enter_idle(int cpu);
extern void set_cpu_sd_state_idle(void);
extern int get_nohz_timer_target(void);
#else
static inline void nohz_balance_enter_idle(int cpu) { }
static inline void set_cpu_sd_state_idle(void) { }
#endif

/*
 * Only dump TASK_* tasks. (0 for all tasks)
 */
extern void show_state_filter(unsigned long state_filter);

static inline void show_state(void)
{
        show_state_filter(0);
}

extern void show_regs(struct pt_regs *);

/*
 * TASK is a pointer to the task whose backtrace we want to see (or NULL for current
 * task), SP is the stack pointer of the first frame that should be shown in the back
 * trace (or NULL if the entire call-chain of the task should be shown).
 */
extern void show_stack(struct task_struct *task, unsigned long *sp);

extern void cpu_init (void);
extern void trap_init(void);
extern void update_process_times(int user);
extern void scheduler_tick(void);
extern int sched_cpu_starting(unsigned int cpu);
extern int sched_cpu_activate(unsigned int cpu);
extern int sched_cpu_deactivate(unsigned int cpu);

#ifdef CONFIG_HOTPLUG_CPU
extern int sched_cpu_dying(unsigned int cpu);
#else
# define sched_cpu_dying        NULL
#endif

extern void sched_show_task(struct task_struct *p);

#ifdef CONFIG_LOCKUP_DETECTOR
extern void touch_softlockup_watchdog_sched(void);
extern void touch_softlockup_watchdog(void);
extern void touch_softlockup_watchdog_sync(void);
extern void touch_all_softlockup_watchdogs(void);
extern int proc_dowatchdog_thresh(struct ctl_table *table, int write,
                                  void __user *buffer,
                                  size_t *lenp, loff_t *ppos);
extern unsigned int  softlockup_panic;
extern unsigned int  hardlockup_panic;
void lockup_detector_init(void);
#else
static inline void touch_softlockup_watchdog_sched(void)
{
}
static inline void touch_softlockup_watchdog(void)
{
}
static inline void touch_softlockup_watchdog_sync(void)
{
}
static inline void touch_all_softlockup_watchdogs(void)
{
}
static inline void lockup_detector_init(void)
{
}
#endif

#ifdef CONFIG_DETECT_HUNG_TASK
void reset_hung_task_detector(void);
#else
static inline void reset_hung_task_detector(void)
{
}
#endif

/* Attach to any functions which should be ignored in wchan output. */
#define __sched         __attribute__((__section__(".sched.text")))

/* Linker adds these: start and end of __sched functions */
extern char __sched_text_start[], __sched_text_end[];

/* Is this address in the __sched functions? */
extern int in_sched_functions(unsigned long addr);

#define MAX_SCHEDULE_TIMEOUT    LONG_MAX
extern signed long schedule_timeout(signed long timeout);
extern signed long schedule_timeout_interruptible(signed long timeout);
extern signed long schedule_timeout_killable(signed long timeout);
extern signed long schedule_timeout_uninterruptible(signed long timeout);
extern signed long schedule_timeout_idle(signed long timeout);
asmlinkage void schedule(void);
extern void schedule_preempt_disabled(void);

extern long io_schedule_timeout(long timeout);

static inline void io_schedule(void)
{
        io_schedule_timeout(MAX_SCHEDULE_TIMEOUT);
}

void __noreturn do_task_dead(void);

struct nsproxy;
struct user_namespace;

#ifdef CONFIG_MMU
extern void arch_pick_mmap_layout(struct mm_struct *mm);
extern unsigned long
arch_get_unmapped_area(struct file *, unsigned long, unsigned long,
                       unsigned long, unsigned long);
extern unsigned long
arch_get_unmapped_area_topdown(struct file *filp, unsigned long addr,
                          unsigned long len, unsigned long pgoff,
                          unsigned long flags);
#else
static inline void arch_pick_mmap_layout(struct mm_struct *mm) {}
#endif

#define SUID_DUMP_DISABLE       0       /* No setuid dumping */
#define SUID_DUMP_USER          1       /* Dump as user of process */
#define SUID_DUMP_ROOT          2       /* Dump as root */

/* mm flags */

/* for SUID_DUMP_* above */
#define MMF_DUMPABLE_BITS 2
#define MMF_DUMPABLE_MASK ((1 << MMF_DUMPABLE_BITS) - 1)

extern void set_dumpable(struct mm_struct *mm, int value);
/*
 * This returns the actual value of the suid_dumpable flag. For things
 * that are using this for checking for privilege transitions, it must
 * test against SUID_DUMP_USER rather than treating it as a boolean
 * value.
 */
static inline int __get_dumpable(unsigned long mm_flags)
{
        return mm_flags & MMF_DUMPABLE_MASK;
}

static inline int get_dumpable(struct mm_struct *mm)
{
        return __get_dumpable(mm->flags);
}

/* coredump filter bits */
#define MMF_DUMP_ANON_PRIVATE   2
#define MMF_DUMP_ANON_SHARED    3
#define MMF_DUMP_MAPPED_PRIVATE 4
#define MMF_DUMP_MAPPED_SHARED  5
#define MMF_DUMP_ELF_HEADERS    6
#define MMF_DUMP_HUGETLB_PRIVATE 7
#define MMF_DUMP_HUGETLB_SHARED  8
#define MMF_DUMP_DAX_PRIVATE    9
#define MMF_DUMP_DAX_SHARED     10

#define MMF_DUMP_FILTER_SHIFT   MMF_DUMPABLE_BITS
#define MMF_DUMP_FILTER_BITS    9
#define MMF_DUMP_FILTER_MASK \
        (((1 << MMF_DUMP_FILTER_BITS) - 1) << MMF_DUMP_FILTER_SHIFT)
#define MMF_DUMP_FILTER_DEFAULT \
        ((1 << MMF_DUMP_ANON_PRIVATE) | (1 << MMF_DUMP_ANON_SHARED) |\
         (1 << MMF_DUMP_HUGETLB_PRIVATE) | MMF_DUMP_MASK_DEFAULT_ELF)

#ifdef CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS
# define MMF_DUMP_MASK_DEFAULT_ELF      (1 << MMF_DUMP_ELF_HEADERS)
#else
# define MMF_DUMP_MASK_DEFAULT_ELF      0
#endif
                                        /* leave room for more dump flags */
#define MMF_VM_MERGEABLE        16      /* KSM may merge identical pages */
#define MMF_VM_HUGEPAGE         17      /* set when VM_HUGEPAGE is set on vma */
/*
 * This one-shot flag is dropped due to necessity of changing exe once again
 * on NFS restore
 */
//#define MMF_EXE_FILE_CHANGED  18      /* see prctl_set_mm_exe_file() */

#define MMF_HAS_UPROBES         19      /* has uprobes */
#define MMF_RECALC_UPROBES      20      /* MMF_HAS_UPROBES can be wrong */
#define MMF_OOM_SKIP            21      /* mm is of no interest for the OOM killer */
#define MMF_UNSTABLE            22      /* mm is unstable for copy_from_user */
#define MMF_HUGE_ZERO_PAGE      23      /* mm has ever used the global huge zero page */

#define MMF_INIT_MASK           (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK)

struct sighand_struct {
        atomic_t                count;
        struct k_sigaction      action[_NSIG];
        spinlock_t              siglock;
        wait_queue_head_t       signalfd_wqh;
};

struct pacct_struct {
        int                     ac_flag;
        long                    ac_exitcode;
        unsigned long           ac_mem;
        cputime_t               ac_utime, ac_stime;
        unsigned long           ac_minflt, ac_majflt;
};

struct cpu_itimer {
        cputime_t expires;
        cputime_t incr;
        u32 error;
        u32 incr_error;
};

/**
 * struct prev_cputime - snaphsot of system and user cputime
 * @utime: time spent in user mode
 * @stime: time spent in system mode
 * @lock: protects the above two fields
 *
 * Stores previous user/system time values such that we can guarantee
 * monotonicity.
 */
struct prev_cputime {
#ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
        cputime_t utime;
        cputime_t stime;
        raw_spinlock_t lock;
#endif
};

static inline void prev_cputime_init(struct prev_cputime *prev)
{
#ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
        prev->utime = prev->stime = 0;
        raw_spin_lock_init(&prev->lock);
#endif
}

/**
 * struct task_cputime - collected CPU time counts
 * @utime:              time spent in user mode, in &cputime_t units
 * @stime:              time spent in kernel mode, in &cputime_t units
 * @sum_exec_runtime:   total time spent on the CPU, in nanoseconds
 *
 * This structure groups together three kinds of CPU time that are tracked for
 * threads and thread groups.  Most things considering CPU time want to group
 * these counts together and treat all three of them in parallel.
 */
struct task_cputime {
        cputime_t utime;
        cputime_t stime;
        unsigned long long sum_exec_runtime;
};

/* Alternate field names when used to cache expirations. */
#define virt_exp        utime
#define prof_exp        stime
#define sched_exp       sum_exec_runtime

#define INIT_CPUTIME    \
        (struct task_cputime) {                                 \
                .utime = 0,                                     \
                .stime = 0,                                     \
                .sum_exec_runtime = 0,                          \
        }

/*
 * This is the atomic variant of task_cputime, which can be used for
 * storing and updating task_cputime statistics without locking.
 */
struct task_cputime_atomic {
        atomic64_t utime;
        atomic64_t stime;
        atomic64_t sum_exec_runtime;
};

#define INIT_CPUTIME_ATOMIC \
        (struct task_cputime_atomic) {                          \
                .utime = ATOMIC64_INIT(0),                      \
                .stime = ATOMIC64_INIT(0),                      \
                .sum_exec_runtime = ATOMIC64_INIT(0),           \
        }

#define PREEMPT_DISABLED        (PREEMPT_DISABLE_OFFSET + PREEMPT_ENABLED)

/*
 * Disable preemption until the scheduler is running -- use an unconditional
 * value so that it also works on !PREEMPT_COUNT kernels.
 *
 * Reset by start_kernel()->sched_init()->init_idle()->init_idle_preempt_count().
 */
#define INIT_PREEMPT_COUNT      PREEMPT_OFFSET

/*
 * Initial preempt_count value; reflects the preempt_count schedule invariant
 * which states that during context switches:
 *
 *    preempt_count() == 2*PREEMPT_DISABLE_OFFSET
 *
 * Note: PREEMPT_DISABLE_OFFSET is 0 for !PREEMPT_COUNT kernels.
 * Note: See finish_task_switch().
 */
#define FORK_PREEMPT_COUNT      (2*PREEMPT_DISABLE_OFFSET + PREEMPT_ENABLED)

/**
 * struct thread_group_cputimer - thread group interval timer counts
 * @cputime_atomic:     atomic thread group interval timers.
 * @running:            true when there are timers running and
 *                      @cputime_atomic receives updates.
 * @checking_timer:     true when a thread in the group is in the
 *                      process of checking for thread group timers.
 *
 * This structure contains the version of task_cputime, above, that is
 * used for thread group CPU timer calculations.
 */
struct thread_group_cputimer {
        struct task_cputime_atomic cputime_atomic;
        bool running;
        bool checking_timer;
};

#include <linux/rwsem.h>
struct autogroup;

/*
 * NOTE! "signal_struct" does not have its own
 * locking, because a shared signal_struct always
 * implies a shared sighand_struct, so locking
 * sighand_struct is always a proper superset of
 * the locking of signal_struct.
 */
struct signal_struct {
        atomic_t                sigcnt;
        atomic_t                live;
        int                     nr_threads;
        struct list_head        thread_head;

        wait_queue_head_t       wait_chldexit;  /* for wait4() */

        /* current thread group signal load-balancing target: */
        struct task_struct      *curr_target;

        /* shared signal handling: */
        struct sigpending       shared_pending;

        /* thread group exit support */
        int                     group_exit_code;
        /* overloaded:
         * - notify group_exit_task when ->count is equal to notify_count
         * - everyone except group_exit_task is stopped during signal delivery
         *   of fatal signals, group_exit_task processes the signal.
         */
        int                     notify_count;
        struct task_struct      *group_exit_task;

        /* thread group stop support, overloads group_exit_code too */
        int                     group_stop_count;
        unsigned int            flags; /* see SIGNAL_* flags below */

        /*
         * PR_SET_CHILD_SUBREAPER marks a process, like a service
         * manager, to re-parent orphan (double-forking) child processes
         * to this process instead of 'init'. The service manager is
         * able to receive SIGCHLD signals and is able to investigate
         * the process until it calls wait(). All children of this
         * process will inherit a flag if they should look for a
         * child_subreaper process at exit.
         */
        unsigned int            is_child_subreaper:1;
        unsigned int            has_child_subreaper:1;

        /* POSIX.1b Interval Timers */
        int                     posix_timer_id;
        struct list_head        posix_timers;

        /* ITIMER_REAL timer for the process */
        struct hrtimer real_timer;
        struct pid *leader_pid;
        ktime_t it_real_incr;

        /*
         * ITIMER_PROF and ITIMER_VIRTUAL timers for the process, we use
         * CPUCLOCK_PROF and CPUCLOCK_VIRT for indexing array as these
         * values are defined to 0 and 1 respectively
         */
        struct cpu_itimer it[2];

        /*
         * Thread group totals for process CPU timers.
         * See thread_group_cputimer(), et al, for details.
         */
        struct thread_group_cputimer cputimer;

        /* Earliest-expiration cache. */
        struct task_cputime cputime_expires;

#ifdef CONFIG_NO_HZ_FULL
        atomic_t tick_dep_mask;
#endif

        struct list_head cpu_timers[3];

        struct pid *tty_old_pgrp;

        /* boolean value for session group leader */
        int leader;

        struct tty_struct *tty; /* NULL if no tty */

#ifdef CONFIG_SCHED_AUTOGROUP
        struct autogroup *autogroup;
#endif
        /*
         * Cumulative resource counters for dead threads in the group,
         * and for reaped dead child processes forked by this group.
         * Live threads maintain their own counters and add to these
         * in __exit_signal, except for the group leader.
         */
        seqlock_t stats_lock;
        cputime_t utime, stime, cutime, cstime;
        cputime_t gtime;
        cputime_t cgtime;
        struct prev_cputime prev_cputime;
        unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
        unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
        unsigned long inblock, oublock, cinblock, coublock;
        unsigned long maxrss, cmaxrss;
        struct task_io_accounting ioac;

        /*
         * Cumulative ns of schedule CPU time fo dead threads in the
         * group, not including a zombie group leader, (This only differs
         * from jiffies_to_ns(utime + stime) if sched_clock uses something
         * other than jiffies.)
         */
        unsigned long long sum_sched_runtime;

        /*
         * We don't bother to synchronize most readers of this at all,
         * because there is no reader checking a limit that actually needs
         * to get both rlim_cur and rlim_max atomically, and either one
         * alone is a single word that can safely be read normally.
         * getrlimit/setrlimit use task_lock(current->group_leader) to
         * protect this instead of the siglock, because they really
         * have no need to disable irqs.
         */
        struct rlimit rlim[RLIM_NLIMITS];

#ifdef CONFIG_BSD_PROCESS_ACCT
        struct pacct_struct pacct;      /* per-process accounting information */
#endif
#ifdef CONFIG_TASKSTATS
        struct taskstats *stats;
#endif
#ifdef CONFIG_AUDIT
        unsigned audit_tty;
        struct tty_audit_buf *tty_audit_buf;
#endif

        /*
         * Thread is the potential origin of an oom condition; kill first on
         * oom
         */
        bool oom_flag_origin;
        short oom_score_adj;            /* OOM kill score adjustment */
        short oom_score_adj_min;        /* OOM kill score adjustment min value.
                                         * Only settable by CAP_SYS_RESOURCE. */
        struct mm_struct *oom_mm;       /* recorded mm when the thread group got
                                         * killed by the oom killer */

        struct mutex cred_guard_mutex;  /* guard against foreign influences on
                                         * credential calculations
                                         * (notably. ptrace) */
};

/*
 * Bits in flags field of signal_struct.
 */
#define SIGNAL_STOP_STOPPED     0x00000001 /* job control stop in effect */
#define SIGNAL_STOP_CONTINUED   0x00000002 /* SIGCONT since WCONTINUED reap */
#define SIGNAL_GROUP_EXIT       0x00000004 /* group exit in progress */
#define SIGNAL_GROUP_COREDUMP   0x00000008 /* coredump in progress */
/*
 * Pending notifications to parent.
 */
#define SIGNAL_CLD_STOPPED      0x00000010
#define SIGNAL_CLD_CONTINUED    0x00000020
#define SIGNAL_CLD_MASK         (SIGNAL_CLD_STOPPED|SIGNAL_CLD_CONTINUED)

#define SIGNAL_UNKILLABLE       0x00000040 /* for init: ignore fatal signals */

#define SIGNAL_STOP_MASK (SIGNAL_CLD_MASK | SIGNAL_STOP_STOPPED | \
                          SIGNAL_STOP_CONTINUED)

static inline void signal_set_stop_flags(struct signal_struct *sig,
                                         unsigned int flags)
{
        WARN_ON(sig->flags & (SIGNAL_GROUP_EXIT|SIGNAL_GROUP_COREDUMP));
        sig->flags = (sig->flags & ~SIGNAL_STOP_MASK) | flags;
}

/* If true, all threads except ->group_exit_task have pending SIGKILL */
static inline int signal_group_exit(const struct signal_struct *sig)
{
        return  (sig->flags & SIGNAL_GROUP_EXIT) ||
                (sig->group_exit_task != NULL);
}

/*
 * Some day this will be a full-fledged user tracking system..
 */
struct user_struct {
        atomic_t __count;       /* reference count */
        atomic_t processes;     /* How many processes does this user have? */
        atomic_t sigpending;    /* How many pending signals does this user have? */
#ifdef CONFIG_INOTIFY_USER
        atomic_t inotify_watches; /* How many inotify watches does this user have? */
        atomic_t inotify_devs;  /* How many inotify devs does this user have opened? */
#endif
#ifdef CONFIG_FANOTIFY
        atomic_t fanotify_listeners;
#endif
#ifdef CONFIG_EPOLL
        atomic_long_t epoll_watches; /* The number of file descriptors currently watched */
#endif
#ifdef CONFIG_POSIX_MQUEUE
        /* protected by mq_lock */
        unsigned long mq_bytes; /* How many bytes can be allocated to mqueue? */
#endif
        unsigned long locked_shm; /* How many pages of mlocked shm ? */
        unsigned long unix_inflight;    /* How many files in flight in unix sockets */
        atomic_long_t pipe_bufs;  /* how many pages are allocated in pipe buffers */

#ifdef CONFIG_KEYS
        struct key *uid_keyring;        /* UID specific keyring */
        struct key *session_keyring;    /* UID's default session keyring */
#endif

        /* Hash table maintenance information */
        struct hlist_node uidhash_node;
        kuid_t uid;

#if defined(CONFIG_PERF_EVENTS) || defined(CONFIG_BPF_SYSCALL)
        atomic_long_t locked_vm;
#endif
};

extern int uids_sysfs_init(void);

extern struct user_struct *find_user(kuid_t);

extern struct user_struct root_user;
#define INIT_USER (&root_user)


struct backing_dev_info;
struct reclaim_state;

#ifdef CONFIG_SCHED_INFO
struct sched_info {
        /* cumulative counters */
        unsigned long pcount;         /* # of times run on this cpu */
        unsigned long long run_delay; /* time spent waiting on a runqueue */

        /* timestamps */
        unsigned long long last_arrival,/* when we last ran on a cpu */
                           last_queued; /* when we were last queued to run */
};
#endif /* CONFIG_SCHED_INFO */

#ifdef CONFIG_TASK_DELAY_ACCT
struct task_delay_info {
        spinlock_t      lock;
        unsigned int    flags;  /* Private per-task flags */

        /* For each stat XXX, add following, aligned appropriately
         *
         * struct timespec XXX_start, XXX_end;
         * u64 XXX_delay;
         * u32 XXX_count;
         *
         * Atomicity of updates to XXX_delay, XXX_count protected by
         * single lock above (split into XXX_lock if contention is an issue).
         */

        /*
         * XXX_count is incremented on every XXX operation, the delay
         * associated with the operation is added to XXX_delay.
         * XXX_delay contains the accumulated delay time in nanoseconds.
         */
        u64 blkio_start;        /* Shared by blkio, swapin */
        u64 blkio_delay;        /* wait for sync block io completion */
        u64 swapin_delay;       /* wait for swapin block io completion */
        u32 blkio_count;        /* total count of the number of sync block */
                                /* io operations performed */
        u32 swapin_count;       /* total count of the number of swapin block */
                                /* io operations performed */

        u64 freepages_start;
        u64 freepages_delay;    /* wait for memory reclaim */
        u32 freepages_count;    /* total count of memory reclaim */
};
#endif  /* CONFIG_TASK_DELAY_ACCT */

static inline int sched_info_on(void)
{
#ifdef CONFIG_SCHEDSTATS
        return 1;
#elif defined(CONFIG_TASK_DELAY_ACCT)
        extern int delayacct_on;
        return delayacct_on;
#else
        return 0;
#endif
}

#ifdef CONFIG_SCHEDSTATS
void force_schedstat_enabled(void);
#endif

enum cpu_idle_type {
        CPU_IDLE,
        CPU_NOT_IDLE,
        CPU_NEWLY_IDLE,
        CPU_MAX_IDLE_TYPES
};

/*
 * Integer metrics need fixed point arithmetic, e.g., sched/fair
 * has a few: load, load_avg, util_avg, freq, and capacity.
 *
 * We define a basic fixed point arithmetic range, and then formalize
 * all these metrics based on that basic range.
 */
# define SCHED_FIXEDPOINT_SHIFT 10
# define SCHED_FIXEDPOINT_SCALE (1L << SCHED_FIXEDPOINT_SHIFT)

/*
 * Increase resolution of cpu_capacity calculations
 */
#define SCHED_CAPACITY_SHIFT    SCHED_FIXEDPOINT_SHIFT
#define SCHED_CAPACITY_SCALE    (1L << SCHED_CAPACITY_SHIFT)

/*
 * Wake-queues are lists of tasks with a pending wakeup, whose
 * callers have already marked the task as woken internally,
 * and can thus carry on. A common use case is being able to
 * do the wakeups once the corresponding user lock as been
 * released.
 *
 * We hold reference to each task in the list across the wakeup,
 * thus guaranteeing that the memory is still valid by the time
 * the actual wakeups are performed in wake_up_q().
 *
 * One per task suffices, because there's never a need for a task to be
 * in two wake queues simultaneously; it is forbidden to abandon a task
 * in a wake queue (a call to wake_up_q() _must_ follow), so if a task is
 * already in a wake queue, the wakeup will happen soon and the second
 * waker can just skip it.
 *
 * The DEFINE_WAKE_Q macro declares and initializes the list head.
 * wake_up_q() does NOT reinitialize the list; it's expected to be
 * called near the end of a function. Otherwise, the list can be
 * re-initialized for later re-use by wake_q_init().
 *
 * Note that this can cause spurious wakeups. schedule() callers
 * must ensure the call is done inside a loop, confirming that the
 * wakeup condition has in fact occurred.
 */
struct wake_q_node {
        struct wake_q_node *next;
};

struct wake_q_head {
        struct wake_q_node *first;
        struct wake_q_node **lastp;
};

#define WAKE_Q_TAIL ((struct wake_q_node *) 0x01)

#define DEFINE_WAKE_Q(name)                             \
        struct wake_q_head name = { WAKE_Q_TAIL, &name.first }

static inline void wake_q_init(struct wake_q_head *head)
{
        head->first = WAKE_Q_TAIL;
        head->lastp = &head->first;
}

extern void wake_q_add(struct wake_q_head *head,
                       struct task_struct *task);
extern void wake_up_q(struct wake_q_head *head);

/*
 * sched-domains (multiprocessor balancing) declarations:
 */
#ifdef CONFIG_SMP
#define SD_LOAD_BALANCE         0x0001  /* Do load balancing on this domain. */
#define SD_BALANCE_NEWIDLE      0x0002  /* Balance when about to become idle */
#define SD_BALANCE_EXEC         0x0004  /* Balance on exec */
#define SD_BALANCE_FORK         0x0008  /* Balance on fork, clone */
#define SD_BALANCE_WAKE         0x0010  /* Balance on wakeup */
#define SD_WAKE_AFFINE          0x0020  /* Wake task to waking CPU */
#define SD_ASYM_CPUCAPACITY     0x0040  /* Groups have different max cpu capacities */
#define SD_SHARE_CPUCAPACITY    0x0080  /* Domain members share cpu capacity */
#define SD_SHARE_POWERDOMAIN    0x0100  /* Domain members share power domain */
#define SD_SHARE_PKG_RESOURCES  0x0200  /* Domain members share cpu pkg resources */
#define SD_SERIALIZE            0x0400  /* Only a single load balancing instance */
#define SD_ASYM_PACKING         0x0800  /* Place busy groups earlier in the domain */
#define SD_PREFER_SIBLING       0x1000  /* Prefer to place tasks in a sibling domain */
#define SD_OVERLAP              0x2000  /* sched_domains of this level overlap */
#define SD_NUMA                 0x4000  /* cross-node balancing */

#ifdef CONFIG_SCHED_SMT
static inline int cpu_smt_flags(void)
{
        return SD_SHARE_CPUCAPACITY | SD_SHARE_PKG_RESOURCES;
}
#endif

#ifdef CONFIG_SCHED_MC
static inline int cpu_core_flags(void)
{
        return SD_SHARE_PKG_RESOURCES;
}
#endif

#ifdef CONFIG_NUMA
static inline int cpu_numa_flags(void)
{
        return SD_NUMA;
}
#endif

extern int arch_asym_cpu_priority(int cpu);

struct sched_domain_attr {
        int relax_domain_level;
};

#define SD_ATTR_INIT    (struct sched_domain_attr) {    \
        .relax_domain_level = -1,                       \
}

extern int sched_domain_level_max;

struct sched_group;

struct sched_domain_shared {
        atomic_t        ref;
        atomic_t        nr_busy_cpus;
        int             has_idle_cores;
};

struct sched_domain {
        /* These fields must be setup */
        struct sched_domain *parent;    /* top domain must be null terminated */
        struct sched_domain *child;     /* bottom domain must be null terminated */
        struct sched_group *groups;     /* the balancing groups of the domain */
        unsigned long min_interval;     /* Minimum balance interval ms */
        unsigned long max_interval;     /* Maximum balance interval ms */
        unsigned int busy_factor;       /* less balancing by factor if busy */
        unsigned int imbalance_pct;     /* No balance until over watermark */
        unsigned int cache_nice_tries;  /* Leave cache hot tasks for # tries */
        unsigned int busy_idx;
        unsigned int idle_idx;
        unsigned int newidle_idx;
        unsigned int wake_idx;
        unsigned int forkexec_idx;
        unsigned int smt_gain;

        int nohz_idle;                  /* NOHZ IDLE status */
        int flags;                      /* See SD_* */
        int level;

        /* Runtime fields. */
        unsigned long last_balance;     /* init to jiffies. units in jiffies */
        unsigned int balance_interval;  /* initialise to 1. units in ms. */
        unsigned int nr_balance_failed; /* initialise to 0 */

        /* idle_balance() stats */
        u64 max_newidle_lb_cost;
        unsigned long next_decay_max_lb_cost;

        u64 avg_scan_cost;              /* select_idle_sibling */

#ifdef CONFIG_SCHEDSTATS
        /* load_balance() stats */
        unsigned int lb_count[CPU_MAX_IDLE_TYPES];
        unsigned int lb_failed[CPU_MAX_IDLE_TYPES];
        unsigned int lb_balanced[CPU_MAX_IDLE_TYPES];
        unsigned int lb_imbalance[CPU_MAX_IDLE_TYPES];
        unsigned int lb_gained[CPU_MAX_IDLE_TYPES];
        unsigned int lb_hot_gained[CPU_MAX_IDLE_TYPES];
        unsigned int lb_nobusyg[CPU_MAX_IDLE_TYPES];
        unsigned int lb_nobusyq[CPU_MAX_IDLE_TYPES];

        /* Active load balancing */
        unsigned int alb_count;
        unsigned int alb_failed;
        unsigned int alb_pushed;

        /* SD_BALANCE_EXEC stats */
        unsigned int sbe_count;
        unsigned int sbe_balanced;
        unsigned int sbe_pushed;

        /* SD_BALANCE_FORK stats */
        unsigned int sbf_count;
        unsigned int sbf_balanced;
        unsigned int sbf_pushed;

        /* try_to_wake_up() stats */
        unsigned int ttwu_wake_remote;
        unsigned int ttwu_move_affine;
        unsigned int ttwu_move_balance;
#endif
#ifdef CONFIG_SCHED_DEBUG
        char *name;
#endif
        union {
                void *private;          /* used during construction */
                struct rcu_head rcu;    /* used during destruction */
        };
        struct sched_domain_shared *shared;

        unsigned int span_weight;
        /*
         * Span of all CPUs in this domain.
         *
         * NOTE: this field is variable length. (Allocated dynamically
         * by attaching extra space to the end of the structure,
         * depending on how many CPUs the kernel has booted up with)
         */
        unsigned long span[0];
};

static inline struct cpumask *sched_domain_span(struct sched_domain *sd)
{
        return to_cpumask(sd->span);
}

extern void partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
                                    struct sched_domain_attr *dattr_new);

/* Allocate an array of sched domains, for partition_sched_domains(). */
cpumask_var_t *alloc_sched_domains(unsigned int ndoms);
void free_sched_domains(cpumask_var_t doms[], unsigned int ndoms);

bool cpus_share_cache(int this_cpu, int that_cpu);

typedef const struct cpumask *(*sched_domain_mask_f)(int cpu);
typedef int (*sched_domain_flags_f)(void);

#define SDTL_OVERLAP    0x01

struct sd_data {
        struct sched_domain **__percpu sd;
        struct sched_domain_shared **__percpu sds;
        struct sched_group **__percpu sg;
        struct sched_group_capacity **__percpu sgc;
};

struct sched_domain_topology_level {
        sched_domain_mask_f mask;
        sched_domain_flags_f sd_flags;
        int                 flags;
        int                 numa_level;
        struct sd_data      data;
#ifdef CONFIG_SCHED_DEBUG
        char                *name;
#endif
};

extern void set_sched_topology(struct sched_domain_topology_level *tl);
extern void wake_up_if_idle(int cpu);

#ifdef CONFIG_SCHED_DEBUG
# define SD_INIT_NAME(type)             .name = #type
#else
# define SD_INIT_NAME(type)
#endif

#else /* CONFIG_SMP */

struct sched_domain_attr;

static inline void
partition_sched_domains(int ndoms_new, cpumask_var_t doms_new[],
                        struct sched_domain_attr *dattr_new)
{
}

static inline bool cpus_share_cache(int this_cpu, int that_cpu)
{
        return true;
}

#endif  /* !CONFIG_SMP */


struct io_context;                      /* See blkdev.h */


#ifdef ARCH_HAS_PREFETCH_SWITCH_STACK
extern void prefetch_stack(struct task_struct *t);
#else
static inline void prefetch_stack(struct task_struct *t) { }
#endif

struct audit_context;           /* See audit.c */
struct mempolicy;
struct pipe_inode_info;
struct uts_namespace;

struct load_weight {
        unsigned long weight;
        u32 inv_weight;
};

/*
 * The load_avg/util_avg accumulates an infinite geometric series
 * (see __update_load_avg() in kernel/sched/fair.c).
 *
 * [load_avg definition]
 *
 *   load_avg = runnable% * scale_load_down(load)
 *
 * where runnable% is the time ratio that a sched_entity is runnable.
 * For cfs_rq, it is the aggregated load_avg of all runnable and
 * blocked sched_entities.
 *
 * load_avg may also take frequency scaling into account:
 *
 *   load_avg = runnable% * scale_load_down(load) * freq%
 *
 * where freq% is the CPU frequency normalized to the highest frequency.
 *
 * [util_avg definition]
 *
 *   util_avg = running% * SCHED_CAPACITY_SCALE
 *
 * where running% is the time ratio that a sched_entity is running on
 * a CPU. For cfs_rq, it is the aggregated util_avg of all runnable
 * and blocked sched_entities.
 *
 * util_avg may also factor frequency scaling and CPU capacity scaling:
 *
 *   util_avg = running% * SCHED_CAPACITY_SCALE * freq% * capacity%
 *
 * where freq% is the same as above, and capacity% is the CPU capacity
 * normalized to the greatest capacity (due to uarch differences, etc).
 *
 * N.B., the above ratios (runnable%, running%, freq%, and capacity%)
 * themselves are in the range of [0, 1]. To do fixed point arithmetics,
 * we therefore scale them to as large a range as necessary. This is for
 * example reflected by util_avg's SCHED_CAPACITY_SCALE.
 *
 * [Overflow issue]
 *
 * The 64-bit load_sum can have 4353082796 (=2^64/47742/88761) entities
 * with the highest load (=88761), always runnable on a single cfs_rq,
 * and should not overflow as the number already hits PID_MAX_LIMIT.
 *
 * For all other cases (including 32-bit kernels), struct load_weight's
 * weight will overflow first before we do, because:
 *
 *    Max(load_avg) <= Max(load.weight)
 *
 * Then it is the load_weight's responsibility to consider overflow
 * issues.
 */
struct sched_avg {
        u64 last_update_time, load_sum;
        u32 util_sum, period_contrib;
        unsigned long load_avg, util_avg;
};

#ifdef CONFIG_SCHEDSTATS
struct sched_statistics {
        u64                     wait_start;
        u64                     wait_max;
        u64                     wait_count;
        u64                     wait_sum;
        u64                     iowait_count;
        u64                     iowait_sum;

        u64                     sleep_start;
        u64                     sleep_max;
        s64                     sum_sleep_runtime;

        u64                     block_start;
        u64                     block_max;
        u64                     exec_max;
        u64                     slice_max;

        u64                     nr_migrations_cold;
        u64                     nr_failed_migrations_affine;
        u64                     nr_failed_migrations_running;
        u64                     nr_failed_migrations_hot;
        u64                     nr_forced_migrations;

        u64                     nr_wakeups;
        u64                     nr_wakeups_sync;
        u64                     nr_wakeups_migrate;
        u64                     nr_wakeups_local;
        u64                     nr_wakeups_remote;
        u64                     nr_wakeups_affine;
        u64                     nr_wakeups_affine_attempts;
        u64                     nr_wakeups_passive;
        u64                     nr_wakeups_idle;
};
#endif

struct sched_entity {
        struct load_weight      load;           /* for load-balancing */
        struct rb_node          run_node;
        struct list_head        group_node;
        unsigned int            on_rq;

        u64                     exec_start;
        u64                     sum_exec_runtime;
        u64                     vruntime;
        u64                     prev_sum_exec_runtime;

        u64                     nr_migrations;

#ifdef CONFIG_SCHEDSTATS
        struct sched_statistics statistics;
#endif

#ifdef CONFIG_FAIR_GROUP_SCHED
        int                     depth;
        struct sched_entity     *parent;
        /* rq on which this entity is (to be) queued: */
        struct cfs_rq           *cfs_rq;
        /* rq "owned" by this entity/group: */
        struct cfs_rq           *my_q;
#endif

#ifdef CONFIG_SMP
        /*
         * Per entity load average tracking.
         *
         * Put into separate cache line so it does not
         * collide with read-mostly values above.
         */
        struct sched_avg        avg ____cacheline_aligned_in_smp;
#endif
};

struct sched_rt_entity {
        struct list_head run_list;
        unsigned long timeout;
        unsigned long watchdog_stamp;
        unsigned int time_slice;
        unsigned short on_rq;
        unsigned short on_list;

        struct sched_rt_entity *back;
#ifdef CONFIG_RT_GROUP_SCHED
        struct sched_rt_entity  *parent;
        /* rq on which this entity is (to be) queued: */
        struct rt_rq            *rt_rq;
        /* rq "owned" by this entity/group: */
        struct rt_rq            *my_q;
#endif
};

struct sched_dl_entity {
        struct rb_node  rb_node;

        /*
         * Original scheduling parameters. Copied here from sched_attr
         * during sched_setattr(), they will remain the same until
         * the next sched_setattr().
         */
        u64 dl_runtime;         /* maximum runtime for each instance    */
        u64 dl_deadline;        /* relative deadline of each instance   */
        u64 dl_period;          /* separation of two instances (period) */
        u64 dl_bw;              /* dl_runtime / dl_deadline             */

        /*
         * Actual scheduling parameters. Initialized with the values above,
         * they are continously updated during task execution. Note that
         * the remaining runtime could be < 0 in case we are in overrun.
         */
        s64 runtime;            /* remaining runtime for this instance  */
        u64 deadline;           /* absolute deadline for this instance  */
        unsigned int flags;     /* specifying the scheduler behaviour   */

        /*
         * Some bool flags:
         *
         * @dl_throttled tells if we exhausted the runtime. If so, the
         * task has to wait for a replenishment to be performed at the
         * next firing of dl_timer.
         *
         * @dl_boosted tells if we are boosted due to DI. If so we are
         * outside bandwidth enforcement mechanism (but only until we
         * exit the critical section);
         *
         * @dl_yielded tells if task gave up the cpu before consuming
         * all its available runtime during the last job.
         */
        int dl_throttled, dl_boosted, dl_yielded;

        /*
         * Bandwidth enforcement timer. Each -deadline task has its
         * own bandwidth to be enforced, thus we need one timer per task.
         */
        struct hrtimer dl_timer;
};

union rcu_special {
        struct {
                u8 blocked;
                u8 need_qs;
                u8 exp_need_qs;
                u8 pad; /* Otherwise the compiler can store garbage here. */
        } b; /* Bits. */
        u32 s; /* Set of bits. */
};
struct rcu_node;

enum perf_event_task_context {
        perf_invalid_context = -1,
        perf_hw_context = 0,
        perf_sw_context,
        perf_nr_task_contexts,
};

/* Track pages that require TLB flushes */
struct tlbflush_unmap_batch {
        /*
         * Each bit set is a CPU that potentially has a TLB entry for one of
         * the PFNs being flushed. See set_tlb_ubc_flush_pending().
         */
        struct cpumask cpumask;

        /* True if any bit in cpumask is set */
        bool flush_required;

        /*
         * If true then the PTE was dirty when unmapped. The entry must be
         * flushed before IO is initiated or a stale TLB entry potentially
         * allows an update without redirtying the page.
         */
        bool writable;
};

struct task_struct {
#ifdef CONFIG_THREAD_INFO_IN_TASK
        /*
         * For reasons of header soup (see current_thread_info()), this
         * must be the first element of task_struct.
         */
        struct thread_info thread_info;
#endif
        volatile long state;    /* -1 unrunnable, 0 runnable, >0 stopped */
        void *stack;
        atomic_t usage;
        unsigned int flags;     /* per process flags, defined below */
        unsigned int ptrace;

#ifdef CONFIG_SMP
        struct llist_node wake_entry;
        int on_cpu;
#ifdef CONFIG_THREAD_INFO_IN_TASK
        unsigned int cpu;       /* current CPU */
#endif
        unsigned int wakee_flips;
        unsigned long wakee_flip_decay_ts;
        struct task_struct *last_wakee;

        int wake_cpu;
#endif
        int on_rq;

        int prio, static_prio, normal_prio;
        unsigned int rt_priority;
        const struct sched_class *sched_class;
        struct sched_entity se;
        struct sched_rt_entity rt;
#ifdef CONFIG_CGROUP_SCHED
        struct task_group *sched_task_group;
#endif
        struct sched_dl_entity dl;

#ifdef CONFIG_PREEMPT_NOTIFIERS
        /* list of struct preempt_notifier: */
        struct hlist_head preempt_notifiers;
#endif

#ifdef CONFIG_BLK_DEV_IO_TRACE
        unsigned int btrace_seq;
#endif

        unsigned int policy;
        int nr_cpus_allowed;
        cpumask_t cpus_allowed;

#ifdef CONFIG_PREEMPT_RCU
        int rcu_read_lock_nesting;
        union rcu_special rcu_read_unlock_special;
        struct list_head rcu_node_entry;
        struct rcu_node *rcu_blocked_node;
#endif /* #ifdef CONFIG_PREEMPT_RCU */
#ifdef CONFIG_TASKS_RCU
        unsigned long rcu_tasks_nvcsw;
        bool rcu_tasks_holdout;
        struct list_head rcu_tasks_holdout_list;
        int rcu_tasks_idle_cpu;
#endif /* #ifdef CONFIG_TASKS_RCU */

#ifdef CONFIG_SCHED_INFO
        struct sched_info sched_info;
#endif

        struct list_head tasks;
#ifdef CONFIG_SMP
        struct plist_node pushable_tasks;
        struct rb_node pushable_dl_tasks;
#endif

        struct mm_struct *mm, *active_mm;
        /* per-thread vma caching */
        u32 vmacache_seqnum;
        struct vm_area_struct *vmacache[VMACACHE_SIZE];
#if defined(SPLIT_RSS_COUNTING)
        struct task_rss_stat    rss_stat;
#endif
/* task state */
        int exit_state;
        int exit_code, exit_signal;
        int pdeath_signal;  /*  The signal sent when the parent dies  */
        unsigned long jobctl;   /* JOBCTL_*, siglock protected */

        /* Used for emulating ABI behavior of previous Linux versions */
        unsigned int personality;

        /* scheduler bits, serialized by scheduler locks */
        unsigned sched_reset_on_fork:1;
        unsigned sched_contributes_to_load:1;
        unsigned sched_migrated:1;
        unsigned sched_remote_wakeup:1;
        unsigned :0; /* force alignment to the next boundary */

        /* unserialized, strictly 'current' */
        unsigned in_execve:1; /* bit to tell LSMs we're in execve */
        unsigned in_iowait:1;
#if !defined(TIF_RESTORE_SIGMASK)
        unsigned restore_sigmask:1;
#endif
#ifdef CONFIG_MEMCG
        unsigned memcg_may_oom:1;
#ifndef CONFIG_SLOB
        unsigned memcg_kmem_skip_account:1;
#endif
#endif
#ifdef CONFIG_COMPAT_BRK
        unsigned brk_randomized:1;
#endif

        unsigned long atomic_flags; /* Flags needing atomic access. */

        struct restart_block restart_block;

        pid_t pid;
        pid_t tgid;

#ifdef CONFIG_CC_STACKPROTECTOR
        /* Canary value for the -fstack-protector gcc feature */
        unsigned long stack_canary;
#endif
        /*
         * pointers to (original) parent process, youngest child, younger sibling,
         * older sibling, respectively.  (p->father can be replaced with
         * p->real_parent->pid)
         */
        struct task_struct __rcu *real_parent; /* real parent process */
        struct task_struct __rcu *parent; /* recipient of SIGCHLD, wait4() reports */
        /*
         * children/sibling forms the list of my natural children
         */
        struct list_head children;      /* list of my children */
        struct list_head sibling;       /* linkage in my parent's children list */
        struct task_struct *group_leader;       /* threadgroup leader */

        /*
         * ptraced is the list of tasks this task is using ptrace on.
         * This includes both natural children and PTRACE_ATTACH targets.
         * p->ptrace_entry is p's link on the p->parent->ptraced list.
         */
        struct list_head ptraced;
        struct list_head ptrace_entry;

        /* PID/PID hash table linkage. */
        struct pid_link pids[PIDTYPE_MAX];
        struct list_head thread_group;
        struct list_head thread_node;

        struct completion *vfork_done;          /* for vfork() */
        int __user *set_child_tid;              /* CLONE_CHILD_SETTID */
        int __user *clear_child_tid;            /* CLONE_CHILD_CLEARTID */

        cputime_t utime, stime;
#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
        cputime_t utimescaled, stimescaled;
#endif
        cputime_t gtime;
        struct prev_cputime prev_cputime;
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
        seqcount_t vtime_seqcount;
        unsigned long long vtime_snap;
        enum {
                /* Task is sleeping or running in a CPU with VTIME inactive */
                VTIME_INACTIVE = 0,
                /* Task runs in userspace in a CPU with VTIME active */
                VTIME_USER,
                /* Task runs in kernelspace in a CPU with VTIME active */
                VTIME_SYS,
        } vtime_snap_whence;
#endif

#ifdef CONFIG_NO_HZ_FULL
        atomic_t tick_dep_mask;
#endif
        unsigned long nvcsw, nivcsw; /* context switch counts */
        u64 start_time;         /* monotonic time in nsec */
        u64 real_start_time;    /* boot based time in nsec */
/* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */
        unsigned long min_flt, maj_flt;

        struct task_cputime cputime_expires;
        struct list_head cpu_timers[3];

/* process credentials */
        const struct cred __rcu *ptracer_cred; /* Tracer's credentials at attach */
        const struct cred __rcu *real_cred; /* objective and real subjective task
                                         * credentials (COW) */
        const struct cred __rcu *cred;  /* effective (overridable) subjective task
                                         * credentials (COW) */
        char comm[TASK_COMM_LEN]; /* executable name excluding path
                                     - access with [gs]et_task_comm (which lock
                                       it with task_lock())
                                     - initialized normally by setup_new_exec */
/* file system info */
        struct nameidata *nameidata;
#ifdef CONFIG_SYSVIPC
/* ipc stuff */
        struct sysv_sem sysvsem;
        struct sysv_shm sysvshm;
#endif
#ifdef CONFIG_DETECT_HUNG_TASK
/* hung task detection */
        unsigned long last_switch_count;
#endif
/* filesystem information */
        struct fs_struct *fs;
/* open file information */
        struct files_struct *files;
/* namespaces */
        struct nsproxy *nsproxy;
/* signal handlers */
        struct signal_struct *signal;
        struct sighand_struct *sighand;

        sigset_t blocked, real_blocked;
        sigset_t saved_sigmask; /* restored if set_restore_sigmask() was used */
        struct sigpending pending;

        unsigned long sas_ss_sp;
        size_t sas_ss_size;
        unsigned sas_ss_flags;

        struct callback_head *task_works;

        struct audit_context *audit_context;
#ifdef CONFIG_AUDITSYSCALL
        kuid_t loginuid;
        unsigned int sessionid;
#endif
        struct seccomp seccomp;

/* Thread group tracking */
        u32 parent_exec_id;
        u32 self_exec_id;
/* Protection of (de-)allocation: mm, files, fs, tty, keyrings, mems_allowed,
 * mempolicy */
        spinlock_t alloc_lock;

        /* Protection of the PI data structures: */
        raw_spinlock_t pi_lock;

        struct wake_q_node wake_q;

#ifdef CONFIG_RT_MUTEXES
        /* PI waiters blocked on a rt_mutex held by this task */
        struct rb_root pi_waiters;
        struct rb_node *pi_waiters_leftmost;
        /* Deadlock detection and priority inheritance handling */
        struct rt_mutex_waiter *pi_blocked_on;
#endif

#ifdef CONFIG_DEBUG_MUTEXES
        /* mutex deadlock detection */
        struct mutex_waiter *blocked_on;
#endif
#ifdef CONFIG_TRACE_IRQFLAGS
        unsigned int irq_events;
        unsigned long hardirq_enable_ip;
        unsigned long hardirq_disable_ip;
        unsigned int hardirq_enable_event;
        unsigned int hardirq_disable_event;
        int hardirqs_enabled;
        int hardirq_context;
        unsigned long softirq_disable_ip;
        unsigned long softirq_enable_ip;
        unsigned int softirq_disable_event;
        unsigned int softirq_enable_event;
        int softirqs_enabled;
        int softirq_context;
#endif
#ifdef CONFIG_LOCKDEP
# define MAX_LOCK_DEPTH 48UL
        u64 curr_chain_key;
        int lockdep_depth;
        unsigned int lockdep_recursion;
        struct held_lock held_locks[MAX_LOCK_DEPTH];
        gfp_t lockdep_reclaim_gfp;
#endif
#ifdef CONFIG_UBSAN
        unsigned int in_ubsan;
#endif

/* journalling filesystem info */
        void *journal_info;

/* stacked block device info */
        struct bio_list *bio_list;

#ifdef CONFIG_BLOCK
/* stack plugging */
        struct blk_plug *plug;
#endif

/* VM state */
        struct reclaim_state *reclaim_state;

        struct backing_dev_info *backing_dev_info;

        struct io_context *io_context;

        unsigned long ptrace_message;
        siginfo_t *last_siginfo; /* For ptrace use.  */
        struct task_io_accounting ioac;
#if defined(CONFIG_TASK_XACCT)
        u64 acct_rss_mem1;      /* accumulated rss usage */
        u64 acct_vm_mem1;       /* accumulated virtual memory usage */
        cputime_t acct_timexpd; /* stime + utime since last update */
#endif
#ifdef CONFIG_CPUSETS
        nodemask_t mems_allowed;        /* Protected by alloc_lock */
        seqcount_t mems_allowed_seq;    /* Seqence no to catch updates */
        int cpuset_mem_spread_rotor;
        int cpuset_slab_spread_rotor;
#endif
#ifdef CONFIG_CGROUPS
        /* Control Group info protected by css_set_lock */
        struct css_set __rcu *cgroups;
        /* cg_list protected by css_set_lock and tsk->alloc_lock */
        struct list_head cg_list;
#endif
#ifdef CONFIG_INTEL_RDT_A
        int closid;
#endif
#ifdef CONFIG_FUTEX
        struct robust_list_head __user *robust_list;
#ifdef CONFIG_COMPAT
        struct compat_robust_list_head __user *compat_robust_list;
#endif
        struct list_head pi_state_list;
        struct futex_pi_state *pi_state_cache;
#endif
#ifdef CONFIG_PERF_EVENTS
        struct perf_event_context *perf_event_ctxp[perf_nr_task_contexts];
        struct mutex perf_event_mutex;
        struct list_head perf_event_list;
#endif
#ifdef CONFIG_DEBUG_PREEMPT
        unsigned long preempt_disable_ip;
#endif
#ifdef CONFIG_NUMA
        struct mempolicy *mempolicy;    /* Protected by alloc_lock */
        short il_next;
        short pref_node_fork;
#endif
#ifdef CONFIG_NUMA_BALANCING
        int numa_scan_seq;
        unsigned int numa_scan_period;
        unsigned int numa_scan_period_max;
        int numa_preferred_nid;
        unsigned long numa_migrate_retry;
        u64 node_stamp;                 /* migration stamp  */
        u64 last_task_numa_placement;
        u64 last_sum_exec_runtime;
        struct callback_head numa_work;

        struct list_head numa_entry;
        struct numa_group *numa_group;

        /*
         * numa_faults is an array split into four regions:
         * faults_memory, faults_cpu, faults_memory_buffer, faults_cpu_buffer
         * in this precise order.
         *
         * faults_memory: Exponential decaying average of faults on a per-node
         * basis. Scheduling placement decisions are made based on these
         * counts. The values remain static for the duration of a PTE scan.
         * faults_cpu: Track the nodes the process was running on when a NUMA
         * hinting fault was incurred.
         * faults_memory_buffer and faults_cpu_buffer: Record faults per node
         * during the current scan window. When the scan completes, the counts
         * in faults_memory and faults_cpu decay and these values are copied.
         */
        unsigned long *numa_faults;
        unsigned long total_numa_faults;

        /*
         * numa_faults_locality tracks if faults recorded during the last
         * scan window were remote/local or failed to migrate. The task scan
         * period is adapted based on the locality of the faults with different
         * weights depending on whether they were shared or private faults
         */
        unsigned long numa_faults_locality[3];

        unsigned long numa_pages_migrated;
#endif /* CONFIG_NUMA_BALANCING */

#ifdef CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH
        struct tlbflush_unmap_batch tlb_ubc;
#endif

        struct rcu_head rcu;

        /*
         * cache last used pipe for splice
         */
        struct pipe_inode_info *splice_pipe;

        struct page_frag task_frag;

#ifdef  CONFIG_TASK_DELAY_ACCT
        struct task_delay_info *delays;
#endif
#ifdef CONFIG_FAULT_INJECTION
        int make_it_fail;
#endif
        /*
         * when (nr_dirtied >= nr_dirtied_pause), it's time to call
         * balance_dirty_pages() for some dirty throttling pause
         */
        int nr_dirtied;
        int nr_dirtied_pause;
        unsigned long dirty_paused_when; /* start of a write-and-pause period */

#ifdef CONFIG_LATENCYTOP
        int latency_record_count;
        struct latency_record latency_record[LT_SAVECOUNT];
#endif
        /*
         * time slack values; these are used to round up poll() and
         * select() etc timeout values. These are in nanoseconds.
         */
        u64 timer_slack_ns;
        u64 default_timer_slack_ns;

#ifdef CONFIG_KASAN
        unsigned int kasan_depth;
#endif
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
        /* Index of current stored address in ret_stack */
        int curr_ret_stack;
        /* Stack of return addresses for return function tracing */
        struct ftrace_ret_stack *ret_stack;
        /* time stamp for last schedule */
        unsigned long long ftrace_timestamp;
        /*
         * Number of functions that haven't been traced
         * because of depth overrun.
         */
        atomic_t trace_overrun;
        /* Pause for the tracing */
        atomic_t tracing_graph_pause;
#endif
#ifdef CONFIG_TRACING
        /* state flags for use by tracers */
        unsigned long trace;
        /* bitmask and counter of trace recursion */
        unsigned long trace_recursion;
#endif /* CONFIG_TRACING */
#ifdef CONFIG_KCOV
        /* Coverage collection mode enabled for this task (0 if disabled). */
        enum kcov_mode kcov_mode;
        /* Size of the kcov_area. */
        unsigned        kcov_size;
        /* Buffer for coverage collection. */
        void            *kcov_area;
        /* kcov desciptor wired with this task or NULL. */
        struct kcov     *kcov;
#endif
#ifdef CONFIG_MEMCG
        struct mem_cgroup *memcg_in_oom;
        gfp_t memcg_oom_gfp_mask;
        int memcg_oom_order;

        /* number of pages to reclaim on returning to userland */
        unsigned int memcg_nr_pages_over_high;
#endif
#ifdef CONFIG_UPROBES
        struct uprobe_task *utask;
#endif
#if defined(CONFIG_BCACHE) || defined(CONFIG_BCACHE_MODULE)
        unsigned int    sequential_io;
        unsigned int    sequential_io_avg;
#endif
#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
        unsigned long   task_state_change;
#endif
        int pagefault_disabled;
#ifdef CONFIG_MMU
        struct task_struct *oom_reaper_list;
#endif
#ifdef CONFIG_VMAP_STACK
        struct vm_struct *stack_vm_area;
#endif
#ifdef CONFIG_THREAD_INFO_IN_TASK
        /* A live task holds one reference. */
        atomic_t stack_refcount;
#endif
/* CPU-specific state of this task */
        struct thread_struct thread;
/*
 * WARNING: on x86, 'thread_struct' contains a variable-sized
 * structure.  It *MUST* be at the end of 'task_struct'.
 *
 * Do not put anything below here!
 */
};

#ifdef CONFIG_ARCH_WANTS_DYNAMIC_TASK_STRUCT
extern int arch_task_struct_size __read_mostly;
#else
# define arch_task_struct_size (sizeof(struct task_struct))
#endif

#ifdef CONFIG_VMAP_STACK
static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t)
{
        return t->stack_vm_area;
}
#else
static inline struct vm_struct *task_stack_vm_area(const struct task_struct *t)
{
        return NULL;
}
#endif

/* Future-safe accessor for struct task_struct's cpus_allowed. */
#define tsk_cpus_allowed(tsk) (&(tsk)->cpus_allowed)

static inline int tsk_nr_cpus_allowed(struct task_struct *p)
{
        return p->nr_cpus_allowed;
}

#define TNF_MIGRATED    0x01
#define TNF_NO_GROUP    0x02
#define TNF_SHARED      0x04
#define TNF_FAULT_LOCAL 0x08
#define TNF_MIGRATE_FAIL 0x10

static inline bool in_vfork(struct task_struct *tsk)
{
        bool ret;

        /*
         * need RCU to access ->real_parent if CLONE_VM was used along with
         * CLONE_PARENT.
         *
         * We check real_parent->mm == tsk->mm because CLONE_VFORK does not
         * imply CLONE_VM
         *
         * CLONE_VFORK can be used with CLONE_PARENT/CLONE_THREAD and thus
         * ->real_parent is not necessarily the task doing vfork(), so in
         * theory we can't rely on task_lock() if we want to dereference it.
         *
         * And in this case we can't trust the real_parent->mm == tsk->mm
         * check, it can be false negative. But we do not care, if init or
         * another oom-unkillable task does this it should blame itself.
         */
        rcu_read_lock();
        ret = tsk->vfork_done && tsk->real_parent->mm == tsk->mm;
        rcu_read_unlock();

        return ret;
}

#ifdef CONFIG_NUMA_BALANCING
extern void task_numa_fault(int last_node, int node, int pages, int flags);
extern pid_t task_numa_group_id(struct task_struct *p);
extern void set_numabalancing_state(bool enabled);
extern void task_numa_free(struct task_struct *p);
extern bool should_numa_migrate_memory(struct task_struct *p, struct page *page,
                                        int src_nid, int dst_cpu);
#else
static inline void task_numa_fault(int last_node, int node, int pages,
                                   int flags)
{
}
static inline pid_t task_numa_group_id(struct task_struct *p)
{
        return 0;
}
static inline void set_numabalancing_state(bool enabled)
{
}
static inline void task_numa_free(struct task_struct *p)
{
}
static inline bool should_numa_migrate_memory(struct task_struct *p,
                                struct page *page, int src_nid, int dst_cpu)
{
        return true;
}
#endif

static inline struct pid *task_pid(struct task_struct *task)
{
        return task->pids[PIDTYPE_PID].pid;
}

static inline struct pid *task_tgid(struct task_struct *task)
{
        return task->group_leader->pids[PIDTYPE_PID].pid;
}

/*
 * Without tasklist or rcu lock it is not safe to dereference
 * the result of task_pgrp/task_session even if task == current,
 * we can race with another thread doing sys_setsid/sys_setpgid.
 */
static inline struct pid *task_pgrp(struct task_struct *task)
{
        return task->group_leader->pids[PIDTYPE_PGID].pid;
}

static inline struct pid *task_session(struct task_struct *task)
{
        return task->group_leader->pids[PIDTYPE_SID].pid;
}

struct pid_namespace;

/*
 * the helpers to get the task's different pids as they are seen
 * from various namespaces
 *
 * task_xid_nr()     : global id, i.e. the id seen from the init namespace;
 * task_xid_vnr()    : virtual id, i.e. the id seen from the pid namespace of
 *                     current.
 * task_xid_nr_ns()  : id seen from the ns specified;
 *
 * set_task_vxid()   : assigns a virtual id to a task;
 *
 * see also pid_nr() etc in include/linux/pid.h
 */
pid_t __task_pid_nr_ns(struct task_struct *task, enum pid_type type,
                        struct pid_namespace *ns);

static inline pid_t task_pid_nr(struct task_struct *tsk)
{
        return tsk->pid;
}

static inline pid_t task_pid_nr_ns(struct task_struct *tsk,
                                        struct pid_namespace *ns)
{
        return __task_pid_nr_ns(tsk, PIDTYPE_PID, ns);
}

static inline pid_t task_pid_vnr(struct task_struct *tsk)
{
        return __task_pid_nr_ns(tsk, PIDTYPE_PID, NULL);
}


static inline pid_t task_tgid_nr(struct task_struct *tsk)
{
        return tsk->tgid;
}

pid_t task_tgid_nr_ns(struct task_struct *tsk, struct pid_namespace *ns);

static inline pid_t task_tgid_vnr(struct task_struct *tsk)
{
        return pid_vnr(task_tgid(tsk));
}


static inline int pid_alive(const struct task_struct *p);
static inline pid_t task_ppid_nr_ns(const struct task_struct *tsk, struct pid_namespace *ns)
{
        pid_t pid = 0;

        rcu_read_lock();
        if (pid_alive(tsk))
                pid = task_tgid_nr_ns(rcu_dereference(tsk->real_parent), ns);
        rcu_read_unlock();

        return pid;
}

static inline pid_t task_ppid_nr(const struct task_struct *tsk)
{
        return task_ppid_nr_ns(tsk, &init_pid_ns);
}

static inline pid_t task_pgrp_nr_ns(struct task_struct *tsk,
                                        struct pid_namespace *ns)
{
        return __task_pid_nr_ns(tsk, PIDTYPE_PGID, ns);
}

static inline pid_t task_pgrp_vnr(struct task_struct *tsk)
{
        return __task_pid_nr_ns(tsk, PIDTYPE_PGID, NULL);
}


static inline pid_t task_session_nr_ns(struct task_struct *tsk,
                                        struct pid_namespace *ns)
{
        return __task_pid_nr_ns(tsk, PIDTYPE_SID, ns);
}

static inline pid_t task_session_vnr(struct task_struct *tsk)
{
        return __task_pid_nr_ns(tsk, PIDTYPE_SID, NULL);
}

/* obsolete, do not use */
static inline pid_t task_pgrp_nr(struct task_struct *tsk)
{
        return task_pgrp_nr_ns(tsk, &init_pid_ns);
}

/**
 * pid_alive - check that a task structure is not stale
 * @p: Task structure to be checked.
 *
 * Test if a process is not yet dead (at most zombie state)
 * If pid_alive fails, then pointers within the task structure
 * can be stale and must not be dereferenced.
 *
 * Return: 1 if the process is alive. 0 otherwise.
 */
static inline int pid_alive(const struct task_struct *p)
{
        return p->pids[PIDTYPE_PID].pid != NULL;
}

/**
 * is_global_init - check if a task structure is init. Since init
 * is free to have sub-threads we need to check tgid.
 * @tsk: Task structure to be checked.
 *
 * Check if a task structure is the first user space task the kernel created.
 *
 * Return: 1 if the task structure is init. 0 otherwise.
 */
static inline int is_global_init(struct task_struct *tsk)
{
        return task_tgid_nr(tsk) == 1;
}

extern struct pid *cad_pid;

extern void free_task(struct task_struct *tsk);
#define get_task_struct(tsk) do { atomic_inc(&(tsk)->usage); } while(0)

extern void __put_task_struct(struct task_struct *t);

static inline void put_task_struct(struct task_struct *t)
{
        if (atomic_dec_and_test(&t->usage))
                __put_task_struct(t);
}

struct task_struct *task_rcu_dereference(struct task_struct **ptask);
struct task_struct *try_get_task_struct(struct task_struct **ptask);

#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
extern void task_cputime(struct task_struct *t,
                         cputime_t *utime, cputime_t *stime);
extern cputime_t task_gtime(struct task_struct *t);
#else
static inline void task_cputime(struct task_struct *t,
                                cputime_t *utime, cputime_t *stime)
{
        *utime = t->utime;
        *stime = t->stime;
}

static inline cputime_t task_gtime(struct task_struct *t)
{
        return t->gtime;
}
#endif

#ifdef CONFIG_ARCH_HAS_SCALED_CPUTIME
static inline void task_cputime_scaled(struct task_struct *t,
                                       cputime_t *utimescaled,
                                       cputime_t *stimescaled)
{
        *utimescaled = t->utimescaled;
        *stimescaled = t->stimescaled;
}
#else
static inline void task_cputime_scaled(struct task_struct *t,
                                       cputime_t *utimescaled,
                                       cputime_t *stimescaled)
{
        task_cputime(t, utimescaled, stimescaled);
}
#endif

extern void task_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st);
extern void thread_group_cputime_adjusted(struct task_struct *p, cputime_t *ut, cputime_t *st);

/*
 * Per process flags
 */
#define PF_IDLE         0x00000002      /* I am an IDLE thread */
#define PF_EXITING      0x00000004      /* getting shut down */
#define PF_EXITPIDONE   0x00000008      /* pi exit done on shut down */
#define PF_VCPU         0x00000010      /* I'm a virtual CPU */
#define PF_WQ_WORKER    0x00000020      /* I'm a workqueue worker */
#define PF_FORKNOEXEC   0x00000040      /* forked but didn't exec */
#define PF_MCE_PROCESS  0x00000080      /* process policy on mce errors */
#define PF_SUPERPRIV    0x00000100      /* used super-user privileges */
#define PF_DUMPCORE     0x00000200      /* dumped core */
#define PF_SIGNALED     0x00000400      /* killed by a signal */
#define PF_MEMALLOC     0x00000800      /* Allocating memory */
#define PF_NPROC_EXCEEDED 0x00001000    /* set_user noticed that RLIMIT_NPROC was exceeded */
#define PF_USED_MATH    0x00002000      /* if unset the fpu must be initialized before use */
#define PF_USED_ASYNC   0x00004000      /* used async_schedule*(), used by module init */
#define PF_NOFREEZE     0x00008000      /* this thread should not be frozen */
#define PF_FROZEN       0x00010000      /* frozen for system suspend */
#define PF_FSTRANS      0x00020000      /* inside a filesystem transaction */
#define PF_KSWAPD       0x00040000      /* I am kswapd */
#define PF_MEMALLOC_NOIO 0x00080000     /* Allocating memory without IO involved */
#define PF_LESS_THROTTLE 0x00100000     /* Throttle me less: I clean memory */
#define PF_KTHREAD      0x00200000      /* I am a kernel thread */
#define PF_RANDOMIZE    0x00400000      /* randomize virtual address space */
#define PF_SWAPWRITE    0x00800000      /* Allowed to write to swap */
#define PF_NO_SETAFFINITY 0x04000000    /* Userland is not allowed to meddle with cpus_allowed */
#define PF_MCE_EARLY    0x08000000      /* Early kill for mce process policy */
#define PF_MUTEX_TESTER 0x20000000      /* Thread belongs to the rt mutex tester */
#define PF_FREEZER_SKIP 0x40000000      /* Freezer should not count it as freezable */
#define PF_SUSPEND_TASK 0x80000000      /* this thread called freeze_processes and should not be frozen */

/*
 * Only the _current_ task can read/write to tsk->flags, but other
 * tasks can access tsk->flags in readonly mode for example
 * with tsk_used_math (like during threaded core dumping).
 * There is however an exception to this rule during ptrace
 * or during fork: the ptracer task is allowed to write to the
 * child->flags of its traced child (same goes for fork, the parent
 * can write to the child->flags), because we're guaranteed the
 * child is not running and in turn not changing child->flags
 * at the same time the parent does it.
 */
#define clear_stopped_child_used_math(child) do { (child)->flags &= ~PF_USED_MATH; } while (0)
#define set_stopped_child_used_math(child) do { (child)->flags |= PF_USED_MATH; } while (0)
#define clear_used_math() clear_stopped_child_used_math(current)
#define set_used_math() set_stopped_child_used_math(current)
#define conditional_stopped_child_used_math(condition, child) \
        do { (child)->flags &= ~PF_USED_MATH, (child)->flags |= (condition) ? PF_USED_MATH : 0; } while (0)
#define conditional_used_math(condition) \
        conditional_stopped_child_used_math(condition, current)
#define copy_to_stopped_child_used_math(child) \
        do { (child)->flags &= ~PF_USED_MATH, (child)->flags |= current->flags & PF_USED_MATH; } while (0)
/* NOTE: this will return 0 or PF_USED_MATH, it will never return 1 */
#define tsk_used_math(p) ((p)->flags & PF_USED_MATH)
#define used_math() tsk_used_math(current)

/* __GFP_IO isn't allowed if PF_MEMALLOC_NOIO is set in current->flags
 * __GFP_FS is also cleared as it implies __GFP_IO.
 */
static inline gfp_t memalloc_noio_flags(gfp_t flags)
{
        if (unlikely(current->flags & PF_MEMALLOC_NOIO))
                flags &= ~(__GFP_IO | __GFP_FS);
        return flags;
}

static inline unsigned int memalloc_noio_save(void)
{
        unsigned int flags = current->flags & PF_MEMALLOC_NOIO;
        current->flags |= PF_MEMALLOC_NOIO;
        return flags;
}

static inline void memalloc_noio_restore(unsigned int flags)
{
        current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags;
}

/* Per-process atomic flags. */
#define PFA_NO_NEW_PRIVS 0      /* May not gain new privileges. */
#define PFA_SPREAD_PAGE  1      /* Spread page cache over cpuset */
#define PFA_SPREAD_SLAB  2      /* Spread some slab caches over cpuset */
#define PFA_LMK_WAITING  3      /* Lowmemorykiller is waiting */


#define TASK_PFA_TEST(name, func)                                       \
        static inline bool task_##func(struct task_struct *p)           \
        { return test_bit(PFA_##name, &p->atomic_flags); }
#define TASK_PFA_SET(name, func)                                        \
        static inline void task_set_##func(struct task_struct *p)       \
        { set_bit(PFA_##name, &p->atomic_flags); }
#define TASK_PFA_CLEAR(name, func)                                      \
        static inline void task_clear_##func(struct task_struct *p)     \
        { clear_bit(PFA_##name, &p->atomic_flags); }

TASK_PFA_TEST(NO_NEW_PRIVS, no_new_privs)
TASK_PFA_SET(NO_NEW_PRIVS, no_new_privs)

TASK_PFA_TEST(SPREAD_PAGE, spread_page)
TASK_PFA_SET(SPREAD_PAGE, spread_page)
TASK_PFA_CLEAR(SPREAD_PAGE, spread_page)

TASK_PFA_TEST(SPREAD_SLAB, spread_slab)
TASK_PFA_SET(SPREAD_SLAB, spread_slab)
TASK_PFA_CLEAR(SPREAD_SLAB, spread_slab)

TASK_PFA_TEST(LMK_WAITING, lmk_waiting)
TASK_PFA_SET(LMK_WAITING, lmk_waiting)

/*
 * task->jobctl flags
 */
#define JOBCTL_STOP_SIGMASK     0xffff  /* signr of the last group stop */

#define JOBCTL_STOP_DEQUEUED_BIT 16     /* stop signal dequeued */
#define JOBCTL_STOP_PENDING_BIT 17      /* task should stop for group stop */
#define JOBCTL_STOP_CONSUME_BIT 18      /* consume group stop count */
#define JOBCTL_TRAP_STOP_BIT    19      /* trap for STOP */
#define JOBCTL_TRAP_NOTIFY_BIT  20      /* trap for NOTIFY */
#define JOBCTL_TRAPPING_BIT     21      /* switching to TRACED */
#define JOBCTL_LISTENING_BIT    22      /* ptracer is listening for events */

#define JOBCTL_STOP_DEQUEUED    (1UL << JOBCTL_STOP_DEQUEUED_BIT)
#define JOBCTL_STOP_PENDING     (1UL << JOBCTL_STOP_PENDING_BIT)
#define JOBCTL_STOP_CONSUME     (1UL << JOBCTL_STOP_CONSUME_BIT)
#define JOBCTL_TRAP_STOP        (1UL << JOBCTL_TRAP_STOP_BIT)
#define JOBCTL_TRAP_NOTIFY      (1UL << JOBCTL_TRAP_NOTIFY_BIT)
#define JOBCTL_TRAPPING         (1UL << JOBCTL_TRAPPING_BIT)
#define JOBCTL_LISTENING        (1UL << JOBCTL_LISTENING_BIT)

#define JOBCTL_TRAP_MASK        (JOBCTL_TRAP_STOP | JOBCTL_TRAP_NOTIFY)
#define JOBCTL_PENDING_MASK     (JOBCTL_STOP_PENDING | JOBCTL_TRAP_MASK)

extern bool task_set_jobctl_pending(struct task_struct *task,
                                    unsigned long mask);
extern void task_clear_jobctl_trapping(struct task_struct *task);
extern void task_clear_jobctl_pending(struct task_struct *task,
                                      unsigned long mask);

static inline void rcu_copy_process(struct task_struct *p)
{
#ifdef CONFIG_PREEMPT_RCU
        p->rcu_read_lock_nesting = 0;
        p->rcu_read_unlock_special.s = 0;
        p->rcu_blocked_node = NULL;
        INIT_LIST_HEAD(&p->rcu_node_entry);
#endif /* #ifdef CONFIG_PREEMPT_RCU */
#ifdef CONFIG_TASKS_RCU
        p->rcu_tasks_holdout = false;
        INIT_LIST_HEAD(&p->rcu_tasks_holdout_list);
        p->rcu_tasks_idle_cpu = -1;
#endif /* #ifdef CONFIG_TASKS_RCU */
}

static inline void tsk_restore_flags(struct task_struct *task,
                                unsigned long orig_flags, unsigned long flags)
{
        task->flags &= ~flags;
        task->flags |= orig_flags & flags;
}

extern int cpuset_cpumask_can_shrink(const struct cpumask *cur,
                                     const struct cpumask *trial);
extern int task_can_attach(struct task_struct *p,
                           const struct cpumask *cs_cpus_allowed);
#ifdef CONFIG_SMP
extern void do_set_cpus_allowed(struct task_struct *p,
                               const struct cpumask *new_mask);

extern int set_cpus_allowed_ptr(struct task_struct *p,
                                const struct cpumask *new_mask);
#else
static inline void do_set_cpus_allowed(struct task_struct *p,
                                      const struct cpumask *new_mask)
{
}
static inline int set_cpus_allowed_ptr(struct task_struct *p,
                                       const struct cpumask *new_mask)
{
        if (!cpumask_test_cpu(0, new_mask))
                return -EINVAL;
        return 0;
}
#endif

#ifdef CONFIG_NO_HZ_COMMON
void calc_load_enter_idle(void);
void calc_load_exit_idle(void);
#else
static inline void calc_load_enter_idle(void) { }
static inline void calc_load_exit_idle(void) { }
#endif /* CONFIG_NO_HZ_COMMON */

#ifndef cpu_relax_yield
#define cpu_relax_yield() cpu_relax()
#endif

/*
 * Do not use outside of architecture code which knows its limitations.
 *
 * sched_clock() has no promise of monotonicity or bounded drift between
 * CPUs, use (which you should not) requires disabling IRQs.
 *
 * Please use one of the three interfaces below.
 */
extern unsigned long long notrace sched_clock(void);
/*
 * See the comment in kernel/sched/clock.c
 */
extern u64 running_clock(void);
extern u64 sched_clock_cpu(int cpu);


extern void sched_clock_init(void);

#ifndef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK
static inline void sched_clock_tick(void)
{
}

static inline void sched_clock_idle_sleep_event(void)
{
}

static inline void sched_clock_idle_wakeup_event(u64 delta_ns)
{
}

static inline u64 cpu_clock(int cpu)
{
        return sched_clock();
}

static inline u64 local_clock(void)
{
        return sched_clock();
}
#else
/*
 * Architectures can set this to 1 if they have specified
 * CONFIG_HAVE_UNSTABLE_SCHED_CLOCK in their arch Kconfig,
 * but then during bootup it turns out that sched_clock()
 * is reliable after all:
 */
extern int sched_clock_stable(void);
extern void set_sched_clock_stable(void);
extern void clear_sched_clock_stable(void);

extern void sched_clock_tick(void);
extern void sched_clock_idle_sleep_event(void);
extern void sched_clock_idle_wakeup_event(u64 delta_ns);

/*
 * As outlined in clock.c, provides a fast, high resolution, nanosecond
 * time source that is monotonic per cpu argument and has bounded drift
 * between cpus.
 *
 * ######################### BIG FAT WARNING ##########################
 * # when comparing cpu_clock(i) to cpu_clock(j) for i != j, time can #
 * # go backwards !!                                                  #
 * ####################################################################
 */
static inline u64 cpu_clock(int cpu)
{
        return sched_clock_cpu(cpu);
}

static inline u64 local_clock(void)
{
        return sched_clock_cpu(raw_smp_processor_id());
}
#endif

#ifdef CONFIG_IRQ_TIME_ACCOUNTING
/*
 * An i/f to runtime opt-in for irq time accounting based off of sched_clock.
 * The reason for this explicit opt-in is not to have perf penalty with
 * slow sched_clocks.
 */
extern void enable_sched_clock_irqtime(void);
extern void disable_sched_clock_irqtime(void);
#else
static inline void enable_sched_clock_irqtime(void) {}
static inline void disable_sched_clock_irqtime(void) {}
#endif

extern unsigned long long
task_sched_runtime(struct task_struct *task);

/* sched_exec is called by processes performing an exec */
#ifdef CONFIG_SMP
extern void sched_exec(void);
#else
#define sched_exec()   {}
#endif

extern void sched_clock_idle_sleep_event(void);
extern void sched_clock_idle_wakeup_event(u64 delta_ns);

#ifdef CONFIG_HOTPLUG_CPU
extern void idle_task_exit(void);
#else
static inline void idle_task_exit(void) {}
#endif

#if defined(CONFIG_NO_HZ_COMMON) && defined(CONFIG_SMP)
extern void wake_up_nohz_cpu(int cpu);
#else
static inline void wake_up_nohz_cpu(int cpu) { }
#endif

#ifdef CONFIG_NO_HZ_FULL
extern u64 scheduler_tick_max_deferment(void);
#endif

#ifdef CONFIG_SCHED_AUTOGROUP
extern void sched_autogroup_create_attach(struct task_struct *p);
extern void sched_autogroup_detach(struct task_struct *p);
extern void sched_autogroup_fork(struct signal_struct *sig);
extern void sched_autogroup_exit(struct signal_struct *sig);
extern void sched_autogroup_exit_task(struct task_struct *p);
#ifdef CONFIG_PROC_FS
extern void proc_sched_autogroup_show_task(struct task_struct *p, struct seq_file *m);
extern int proc_sched_autogroup_set_nice(struct task_struct *p, int nice);
#endif
#else
static inline void sched_autogroup_create_attach(struct task_struct *p) { }
static inline void sched_autogroup_detach(struct task_struct *p) { }
static inline void sched_autogroup_fork(struct signal_struct *sig) { }
static inline void sched_autogroup_exit(struct signal_struct *sig) { }
static inline void sched_autogroup_exit_task(struct task_struct *p) { }
#endif

extern int yield_to(struct task_struct *p, bool preempt);
extern void set_user_nice(struct task_struct *p, long nice);
extern int task_prio(const struct task_struct *p);
/**
 * task_nice - return the nice value of a given task.
 * @p: the task in question.
 *
 * Return: The nice value [ -20 ... 0 ... 19 ].
 */
static inline int task_nice(const struct task_struct *p)
{
        return PRIO_TO_NICE((p)->static_prio);
}
extern int can_nice(const struct task_struct *p, const int nice);
extern int task_curr(const struct task_struct *p);
extern int idle_cpu(int cpu);
extern int sched_setscheduler(struct task_struct *, int,
                              const struct sched_param *);
extern int sched_setscheduler_nocheck(struct task_struct *, int,
                                      const struct sched_param *);
extern int sched_setattr(struct task_struct *,
                         const struct sched_attr *);
extern struct task_struct *idle_task(int cpu);
/**
 * is_idle_task - is the specified task an idle task?
 * @p: the task in question.
 *
 * Return: 1 if @p is an idle task. 0 otherwise.
 */
static inline bool is_idle_task(const struct task_struct *p)
{
        return !!(p->flags & PF_IDLE);
}
extern struct task_struct *curr_task(int cpu);
extern void ia64_set_curr_task(int cpu, struct task_struct *p);

void yield(void);

union thread_union {
#ifndef CONFIG_THREAD_INFO_IN_TASK
        struct thread_info thread_info;
#endif
        unsigned long stack[THREAD_SIZE/sizeof(long)];
};

#ifndef __HAVE_ARCH_KSTACK_END
static inline int kstack_end(void *addr)
{
        /* Reliable end of stack detection:
         * Some APM bios versions misalign the stack
         */
        return !(((unsigned long)addr+sizeof(void*)-1) & (THREAD_SIZE-sizeof(void*)));
}
#endif

extern union thread_union init_thread_union;
extern struct task_struct init_task;

extern struct   mm_struct init_mm;

extern struct pid_namespace init_pid_ns;

/*
 * find a task by one of its numerical ids
 *
 * find_task_by_pid_ns():
 *      finds a task by its pid in the specified namespace
 * find_task_by_vpid():
 *      finds a task by its virtual pid
 *
 * see also find_vpid() etc in include/linux/pid.h
 */

extern struct task_struct *find_task_by_vpid(pid_t nr);
extern struct task_struct *find_task_by_pid_ns(pid_t nr,
                struct pid_namespace *ns);

/* per-UID process charging. */
extern struct user_struct * alloc_uid(kuid_t);
static inline struct user_struct *get_uid(struct user_struct *u)
{
        atomic_inc(&u->__count);
        return u;
}
extern void free_uid(struct user_struct *);

#include <asm/current.h>

extern void xtime_update(unsigned long ticks);

extern int wake_up_state(struct task_struct *tsk, unsigned int state);
extern int wake_up_process(struct task_struct *tsk);
extern void wake_up_new_task(struct task_struct *tsk);
#ifdef CONFIG_SMP
 extern void kick_process(struct task_struct *tsk);
#else
 static inline void kick_process(struct task_struct *tsk) { }
#endif
extern int sched_fork(unsigned long clone_flags, struct task_struct *p);
extern void sched_dead(struct task_struct *p);

extern void proc_caches_init(void);
extern void flush_signals(struct task_struct *);
extern void ignore_signals(struct task_struct *);
extern void flush_signal_handlers(struct task_struct *, int force_default);
extern int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info);

static inline int kernel_dequeue_signal(siginfo_t *info)
{
        struct task_struct *tsk = current;
        siginfo_t __info;
        int ret;

        spin_lock_irq(&tsk->sighand->siglock);
        ret = dequeue_signal(tsk, &tsk->blocked, info ?: &__info);
        spin_unlock_irq(&tsk->sighand->siglock);

        return ret;
}

static inline void kernel_signal_stop(void)
{
        spin_lock_irq(&current->sighand->siglock);
        if (current->jobctl & JOBCTL_STOP_DEQUEUED)
                __set_current_state(TASK_STOPPED);
        spin_unlock_irq(&current->sighand->siglock);

        schedule();
}

extern void release_task(struct task_struct * p);
extern int send_sig_info(int, struct siginfo *, struct task_struct *);
extern int force_sigsegv(int, struct task_struct *);
extern int force_sig_info(int, struct siginfo *, struct task_struct *);
extern int __kill_pgrp_info(int sig, struct siginfo *info, struct pid *pgrp);
extern int kill_pid_info(int sig, struct siginfo *info, struct pid *pid);
extern int kill_pid_info_as_cred(int, struct siginfo *, struct pid *,
                                const struct cred *, u32);
extern int kill_pgrp(struct pid *pid, int sig, int priv);
extern int kill_pid(struct pid *pid, int sig, int priv);
extern int kill_proc_info(int, struct siginfo *, pid_t);
extern __must_check bool do_notify_parent(struct task_struct *, int);
extern void __wake_up_parent(struct task_struct *p, struct task_struct *parent);
extern void force_sig(int, struct task_struct *);
extern int send_sig(int, struct task_struct *, int);
extern int zap_other_threads(struct task_struct *p);
extern struct sigqueue *sigqueue_alloc(void);
extern void sigqueue_free(struct sigqueue *);
extern int send_sigqueue(struct sigqueue *,  struct task_struct *, int group);
extern int do_sigaction(int, struct k_sigaction *, struct k_sigaction *);

#ifdef TIF_RESTORE_SIGMASK
/*
 * Legacy restore_sigmask accessors.  These are inefficient on
 * SMP architectures because they require atomic operations.
 */

/**
 * set_restore_sigmask() - make sure saved_sigmask processing gets done
 *
 * This sets TIF_RESTORE_SIGMASK and ensures that the arch signal code
 * will run before returning to user mode, to process the flag.  For
 * all callers, TIF_SIGPENDING is already set or it's no harm to set
 * it.  TIF_RESTORE_SIGMASK need not be in the set of bits that the
 * arch code will notice on return to user mode, in case those bits
 * are scarce.  We set TIF_SIGPENDING here to ensure that the arch
 * signal code always gets run when TIF_RESTORE_SIGMASK is set.
 */
static inline void set_restore_sigmask(void)
{
        set_thread_flag(TIF_RESTORE_SIGMASK);
        WARN_ON(!test_thread_flag(TIF_SIGPENDING));
}
static inline void clear_restore_sigmask(void)
{
        clear_thread_flag(TIF_RESTORE_SIGMASK);
}
static inline bool test_restore_sigmask(void)
{
        return test_thread_flag(TIF_RESTORE_SIGMASK);
}
static inline bool test_and_clear_restore_sigmask(void)
{
        return test_and_clear_thread_flag(TIF_RESTORE_SIGMASK);
}

#else   /* TIF_RESTORE_SIGMASK */

/* Higher-quality implementation, used if TIF_RESTORE_SIGMASK doesn't exist. */
static inline void set_restore_sigmask(void)
{
        current->restore_sigmask = true;
        WARN_ON(!test_thread_flag(TIF_SIGPENDING));
}
static inline void clear_restore_sigmask(void)
{
        current->restore_sigmask = false;
}
static inline bool test_restore_sigmask(void)
{
        return current->restore_sigmask;
}
static inline bool test_and_clear_restore_sigmask(void)
{
        if (!current->restore_sigmask)
                return false;
        current->restore_sigmask = false;
        return true;
}
#endif

static inline void restore_saved_sigmask(void)
{
        if (test_and_clear_restore_sigmask())
                __set_current_blocked(&current->saved_sigmask);
}

static inline sigset_t *sigmask_to_save(void)
{
        sigset_t *res = &current->blocked;
        if (unlikely(test_restore_sigmask()))
                res = &current->saved_sigmask;
        return res;
}

static inline int kill_cad_pid(int sig, int priv)
{
        return kill_pid(cad_pid, sig, priv);
}

/* These can be the second arg to send_sig_info/send_group_sig_info.  */
#define SEND_SIG_NOINFO ((struct siginfo *) 0)
#define SEND_SIG_PRIV   ((struct siginfo *) 1)
#define SEND_SIG_FORCED ((struct siginfo *) 2)

/*
 * True if we are on the alternate signal stack.
 */
static inline int on_sig_stack(unsigned long sp)
{
        /*
         * If the signal stack is SS_AUTODISARM then, by construction, we
         * can't be on the signal stack unless user code deliberately set
         * SS_AUTODISARM when we were already on it.
         *
         * This improves reliability: if user state gets corrupted such that
         * the stack pointer points very close to the end of the signal stack,
         * then this check will enable the signal to be handled anyway.
         */
        if (current->sas_ss_flags & SS_AUTODISARM)
                return 0;

#ifdef CONFIG_STACK_GROWSUP
        return sp >= current->sas_ss_sp &&
                sp - current->sas_ss_sp < current->sas_ss_size;
#else
        return sp > current->sas_ss_sp &&
                sp - current->sas_ss_sp <= current->sas_ss_size;
#endif
}

static inline int sas_ss_flags(unsigned long sp)
{
        if (!current->sas_ss_size)
                return SS_DISABLE;

        return on_sig_stack(sp) ? SS_ONSTACK : 0;
}

static inline void sas_ss_reset(struct task_struct *p)
{
        p->sas_ss_sp = 0;
        p->sas_ss_size = 0;
        p->sas_ss_flags = SS_DISABLE;
}

static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig)
{
        if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp))
#ifdef CONFIG_STACK_GROWSUP
                return current->sas_ss_sp;
#else
                return current->sas_ss_sp + current->sas_ss_size;
#endif
        return sp;
}

/*
 * Routines for handling mm_structs
 */
extern struct mm_struct * mm_alloc(void);

/* mmdrop drops the mm and the page tables */
extern void __mmdrop(struct mm_struct *);
static inline void mmdrop(struct mm_struct *mm)
{
        if (unlikely(atomic_dec_and_test(&mm->mm_count)))
                __mmdrop(mm);
}

static inline void mmdrop_async_fn(struct work_struct *work)
{
        struct mm_struct *mm = container_of(work, struct mm_struct, async_put_work);
        __mmdrop(mm);
}

static inline void mmdrop_async(struct mm_struct *mm)
{
        if (unlikely(atomic_dec_and_test(&mm->mm_count))) {
                INIT_WORK(&mm->async_put_work, mmdrop_async_fn);
                schedule_work(&mm->async_put_work);
        }
}

static inline bool mmget_not_zero(struct mm_struct *mm)
{
        return atomic_inc_not_zero(&mm->mm_users);
}

/* mmput gets rid of the mappings and all user-space */
extern void mmput(struct mm_struct *);
#ifdef CONFIG_MMU
/* same as above but performs the slow path from the async context. Can
 * be called from the atomic context as well
 */
extern void mmput_async(struct mm_struct *);
#endif

/* Grab a reference to a task's mm, if it is not already going away */
extern struct mm_struct *get_task_mm(struct task_struct *task);
/*
 * Grab a reference to a task's mm, if it is not already going away
 * and ptrace_may_access with the mode parameter passed to it
 * succeeds.
 */
extern struct mm_struct *mm_access(struct task_struct *task, unsigned int mode);
/* Remove the current tasks stale references to the old mm_struct */
extern void mm_release(struct task_struct *, struct mm_struct *);

#ifdef CONFIG_HAVE_COPY_THREAD_TLS
extern int copy_thread_tls(unsigned long, unsigned long, unsigned long,
                        struct task_struct *, unsigned long);
#else
extern int copy_thread(unsigned long, unsigned long, unsigned long,
                        struct task_struct *);

/* Architectures that haven't opted into copy_thread_tls get the tls argument
 * via pt_regs, so ignore the tls argument passed via C. */
static inline int copy_thread_tls(
                unsigned long clone_flags, unsigned long sp, unsigned long arg,
                struct task_struct *p, unsigned long tls)
{
        return copy_thread(clone_flags, sp, arg, p);
}
#endif
extern void flush_thread(void);

#ifdef CONFIG_HAVE_EXIT_THREAD
extern void exit_thread(struct task_struct *tsk);
#else
static inline void exit_thread(struct task_struct *tsk)
{
}
#endif

extern void exit_files(struct task_struct *);
extern void __cleanup_sighand(struct sighand_struct *);

extern void exit_itimers(struct signal_struct *);
extern void flush_itimer_signals(void);

extern void do_group_exit(int);

extern int do_execve(struct filename *,
                     const char __user * const __user *,
                     const char __user * const __user *);
extern int do_execveat(int, struct filename *,
                       const char __user * const __user *,
                       const char __user * const __user *,
                       int);
extern long _do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *, unsigned long);
extern long do_fork(unsigned long, unsigned long, unsigned long, int __user *, int __user *);
struct task_struct *fork_idle(int);
extern pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags);

extern void __set_task_comm(struct task_struct *tsk, const char *from, bool exec);
static inline void set_task_comm(struct task_struct *tsk, const char *from)
{
        __set_task_comm(tsk, from, false);
}
extern char *get_task_comm(char *to, struct task_struct *tsk);

#ifdef CONFIG_SMP
void scheduler_ipi(void);
extern unsigned long wait_task_inactive(struct task_struct *, long match_state);
#else
static inline void scheduler_ipi(void) { }
static inline unsigned long wait_task_inactive(struct task_struct *p,
                                               long match_state)
{
        return 1;
}
#endif

#define tasklist_empty() \
        list_empty(&init_task.tasks)

#define next_task(p) \
        list_entry_rcu((p)->tasks.next, struct task_struct, tasks)

#define for_each_process(p) \
        for (p = &init_task ; (p = next_task(p)) != &init_task ; )

extern bool current_is_single_threaded(void);

/*
 * Careful: do_each_thread/while_each_thread is a double loop so
 *          'break' will not work as expected - use goto instead.
 */
#define do_each_thread(g, t) \
        for (g = t = &init_task ; (g = t = next_task(g)) != &init_task ; ) do

#define while_each_thread(g, t) \
        while ((t = next_thread(t)) != g)

#define __for_each_thread(signal, t)    \
        list_for_each_entry_rcu(t, &(signal)->thread_head, thread_node)

#define for_each_thread(p, t)           \
        __for_each_thread((p)->signal, t)

/* Careful: this is a double loop, 'break' won't work as expected. */
#define for_each_process_thread(p, t)   \
        for_each_process(p) for_each_thread(p, t)

static inline int get_nr_threads(struct task_struct *tsk)
{
        return tsk->signal->nr_threads;
}

static inline bool thread_group_leader(struct task_struct *p)
{
        return p->exit_signal >= 0;
}

/* Do to the insanities of de_thread it is possible for a process
 * to have the pid of the thread group leader without actually being
 * the thread group leader.  For iteration through the pids in proc
 * all we care about is that we have a task with the appropriate
 * pid, we don't actually care if we have the right task.
 */
static inline bool has_group_leader_pid(struct task_struct *p)
{
        return task_pid(p) == p->signal->leader_pid;
}

static inline
bool same_thread_group(struct task_struct *p1, struct task_struct *p2)
{
        return p1->signal == p2->signal;
}

static inline struct task_struct *next_thread(const struct task_struct *p)
{
        return list_entry_rcu(p->thread_group.next,
                              struct task_struct, thread_group);
}

static inline int thread_group_empty(struct task_struct *p)
{
        return list_empty(&p->thread_group);
}

#define delay_group_leader(p) \
                (thread_group_leader(p) && !thread_group_empty(p))

/*
 * Protects ->fs, ->files, ->mm, ->group_info, ->comm, keyring
 * subscriptions and synchronises with wait4().  Also used in procfs.  Also
 * pins the final release of task.io_context.  Also protects ->cpuset and
 * ->cgroup.subsys[]. And ->vfork_done.
 *
 * Nests both inside and outside of read_lock(&tasklist_lock).
 * It must not be nested with write_lock_irq(&tasklist_lock),
 * neither inside nor outside.
 */
static inline void task_lock(struct task_struct *p)
{
        spin_lock(&p->alloc_lock);
}

static inline void task_unlock(struct task_struct *p)
{
        spin_unlock(&p->alloc_lock);
}

extern struct sighand_struct *__lock_task_sighand(struct task_struct *tsk,
                                                        unsigned long *flags);

static inline struct sighand_struct *lock_task_sighand(struct task_struct *tsk,
                                                       unsigned long *flags)
{
        struct sighand_struct *ret;

        ret = __lock_task_sighand(tsk, flags);
        (void)__cond_lock(&tsk->sighand->siglock, ret);
        return ret;
}

static inline void unlock_task_sighand(struct task_struct *tsk,
                                                unsigned long *flags)
{
        spin_unlock_irqrestore(&tsk->sighand->siglock, *flags);
}

/**
 * threadgroup_change_begin - mark the beginning of changes to a threadgroup
 * @tsk: task causing the changes
 *
 * All operations which modify a threadgroup - a new thread joining the
 * group, death of a member thread (the assertion of PF_EXITING) and
 * exec(2) dethreading the process and replacing the leader - are wrapped
 * by threadgroup_change_{begin|end}().  This is to provide a place which
 * subsystems needing threadgroup stability can hook into for
 * synchronization.
 */
static inline void threadgroup_change_begin(struct task_struct *tsk)
{
        might_sleep();
        cgroup_threadgroup_change_begin(tsk);
}

/**
 * threadgroup_change_end - mark the end of changes to a threadgroup
 * @tsk: task causing the changes
 *
 * See threadgroup_change_begin().
 */
static inline void threadgroup_change_end(struct task_struct *tsk)
{
        cgroup_threadgroup_change_end(tsk);
}

#ifdef CONFIG_THREAD_INFO_IN_TASK

static inline struct thread_info *task_thread_info(struct task_struct *task)
{
        return &task->thread_info;
}

/*
 * When accessing the stack of a non-current task that might exit, use
 * try_get_task_stack() instead.  task_stack_page will return a pointer
 * that could get freed out from under you.
 */
static inline void *task_stack_page(const struct task_struct *task)
{
        return task->stack;
}

#define setup_thread_stack(new,old)     do { } while(0)

static inline unsigned long *end_of_stack(const struct task_struct *task)
{
        return task->stack;
}

#elif !defined(__HAVE_THREAD_FUNCTIONS)

#define task_thread_info(task)  ((struct thread_info *)(task)->stack)
#define task_stack_page(task)   ((void *)(task)->stack)

static inline void setup_thread_stack(struct task_struct *p, struct task_struct *org)
{
        *task_thread_info(p) = *task_thread_info(org);
        task_thread_info(p)->task = p;
}

/*
 * Return the address of the last usable long on the stack.
 *
 * When the stack grows down, this is just above the thread
 * info struct. Going any lower will corrupt the threadinfo.
 *
 * When the stack grows up, this is the highest address.
 * Beyond that position, we corrupt data on the next page.
 */
static inline unsigned long *end_of_stack(struct task_struct *p)
{
#ifdef CONFIG_STACK_GROWSUP
        return (unsigned long *)((unsigned long)task_thread_info(p) + THREAD_SIZE) - 1;
#else
        return (unsigned long *)(task_thread_info(p) + 1);
#endif
}

#endif

#ifdef CONFIG_THREAD_INFO_IN_TASK
static inline void *try_get_task_stack(struct task_struct *tsk)
{
        return atomic_inc_not_zero(&tsk->stack_refcount) ?
                task_stack_page(tsk) : NULL;
}

extern void put_task_stack(struct task_struct *tsk);
#else
static inline void *try_get_task_stack(struct task_struct *tsk)
{
        return task_stack_page(tsk);
}

static inline void put_task_stack(struct task_struct *tsk) {}
#endif

#define task_stack_end_corrupted(task) \
                (*(end_of_stack(task)) != STACK_END_MAGIC)

static inline int object_is_on_stack(void *obj)
{
        void *stack = task_stack_page(current);

        return (obj >= stack) && (obj < (stack + THREAD_SIZE));
}

extern void thread_stack_cache_init(void);

#ifdef CONFIG_DEBUG_STACK_USAGE
static inline unsigned long stack_not_used(struct task_struct *p)
{
        unsigned long *n = end_of_stack(p);

        do {    /* Skip over canary */
# ifdef CONFIG_STACK_GROWSUP
                n--;
# else
                n++;
# endif
        } while (!*n);

# ifdef CONFIG_STACK_GROWSUP
        return (unsigned long)end_of_stack(p) - (unsigned long)n;
# else
        return (unsigned long)n - (unsigned long)end_of_stack(p);
# endif
}
#endif
extern void set_task_stack_end_magic(struct task_struct *tsk);

/* set thread flags in other task's structures
 * - see asm/thread_info.h for TIF_xxxx flags available
 */
static inline void set_tsk_thread_flag(struct task_struct *tsk, int flag)
{
        set_ti_thread_flag(task_thread_info(tsk), flag);
}

static inline void clear_tsk_thread_flag(struct task_struct *tsk, int flag)
{
        clear_ti_thread_flag(task_thread_info(tsk), flag);
}

static inline int test_and_set_tsk_thread_flag(struct task_struct *tsk, int flag)
{
        return test_and_set_ti_thread_flag(task_thread_info(tsk), flag);
}

static inline int test_and_clear_tsk_thread_flag(struct task_struct *tsk, int flag)
{
        return test_and_clear_ti_thread_flag(task_thread_info(tsk), flag);
}

static inline int test_tsk_thread_flag(struct task_struct *tsk, int flag)
{
        return test_ti_thread_flag(task_thread_info(tsk), flag);
}

static inline void set_tsk_need_resched(struct task_struct *tsk)
{
        set_tsk_thread_flag(tsk,TIF_NEED_RESCHED);
}

static inline void clear_tsk_need_resched(struct task_struct *tsk)
{
        clear_tsk_thread_flag(tsk,TIF_NEED_RESCHED);
}

static inline int test_tsk_need_resched(struct task_struct *tsk)
{
        return unlikely(test_tsk_thread_flag(tsk,TIF_NEED_RESCHED));
}

static inline int restart_syscall(void)
{
        set_tsk_thread_flag(current, TIF_SIGPENDING);
        return -ERESTARTNOINTR;
}

static inline int signal_pending(struct task_struct *p)
{
        return unlikely(test_tsk_thread_flag(p,TIF_SIGPENDING));
}

static inline int __fatal_signal_pending(struct task_struct *p)
{
        return unlikely(sigismember(&p->pending.signal, SIGKILL));
}

static inline int fatal_signal_pending(struct task_struct *p)
{
        return signal_pending(p) && __fatal_signal_pending(p);
}

static inline int signal_pending_state(long state, struct task_struct *p)
{
        if (!(state & (TASK_INTERRUPTIBLE | TASK_WAKEKILL)))
                return 0;
        if (!signal_pending(p))
                return 0;

        return (state & TASK_INTERRUPTIBLE) || __fatal_signal_pending(p);
}

/*
 * cond_resched() and cond_resched_lock(): latency reduction via
 * explicit rescheduling in places that are safe. The return
 * value indicates whether a reschedule was done in fact.
 * cond_resched_lock() will drop the spinlock before scheduling,
 * cond_resched_softirq() will enable bhs before scheduling.
 */
#ifndef CONFIG_PREEMPT
extern int _cond_resched(void);
#else
static inline int _cond_resched(void) { return 0; }
#endif

#define cond_resched() ({                       \
        ___might_sleep(__FILE__, __LINE__, 0);  \
        _cond_resched();                        \
})

extern int __cond_resched_lock(spinlock_t *lock);

#define cond_resched_lock(lock) ({                              \
        ___might_sleep(__FILE__, __LINE__, PREEMPT_LOCK_OFFSET);\
        __cond_resched_lock(lock);                              \
})

extern int __cond_resched_softirq(void);

#define cond_resched_softirq() ({                                       \
        ___might_sleep(__FILE__, __LINE__, SOFTIRQ_DISABLE_OFFSET);     \
        __cond_resched_softirq();                                       \
})

static inline void cond_resched_rcu(void)
{
#if defined(CONFIG_DEBUG_ATOMIC_SLEEP) || !defined(CONFIG_PREEMPT_RCU)
        rcu_read_unlock();
        cond_resched();
        rcu_read_lock();
#endif
}

static inline unsigned long get_preempt_disable_ip(struct task_struct *p)
{
#ifdef CONFIG_DEBUG_PREEMPT
        return p->preempt_disable_ip;
#else
        return 0;
#endif
}

/*
 * Does a critical section need to be broken due to another
 * task waiting?: (technically does not depend on CONFIG_PREEMPT,
 * but a general need for low latency)
 */
static inline int spin_needbreak(spinlock_t *lock)
{
#ifdef CONFIG_PREEMPT
        return spin_is_contended(lock);
#else
        return 0;
#endif
}

/*
 * Idle thread specific functions to determine the need_resched
 * polling state.
 */
#ifdef TIF_POLLING_NRFLAG
static inline int tsk_is_polling(struct task_struct *p)
{
        return test_tsk_thread_flag(p, TIF_POLLING_NRFLAG);
}

static inline void __current_set_polling(void)
{
        set_thread_flag(TIF_POLLING_NRFLAG);
}

static inline bool __must_check current_set_polling_and_test(void)
{
        __current_set_polling();

        /*
         * Polling state must be visible before we test NEED_RESCHED,
         * paired by resched_curr()
         */
        smp_mb__after_atomic();

        return unlikely(tif_need_resched());
}

static inline void __current_clr_polling(void)
{
        clear_thread_flag(TIF_POLLING_NRFLAG);
}

static inline bool __must_check current_clr_polling_and_test(void)
{
        __current_clr_polling();

        /*
         * Polling state must be visible before we test NEED_RESCHED,
         * paired by resched_curr()
         */
        smp_mb__after_atomic();

        return unlikely(tif_need_resched());
}

#else
static inline int tsk_is_polling(struct task_struct *p) { return 0; }
static inline void __current_set_polling(void) { }
static inline void __current_clr_polling(void) { }

static inline bool __must_check current_set_polling_and_test(void)
{
        return unlikely(tif_need_resched());
}
static inline bool __must_check current_clr_polling_and_test(void)
{
        return unlikely(tif_need_resched());
}
#endif

static inline void current_clr_polling(void)
{
        __current_clr_polling();

        /*
         * Ensure we check TIF_NEED_RESCHED after we clear the polling bit.
         * Once the bit is cleared, we'll get IPIs with every new
         * TIF_NEED_RESCHED and the IPI handler, scheduler_ipi(), will also
         * fold.
         */
        smp_mb(); /* paired with resched_curr() */

        preempt_fold_need_resched();
}

static __always_inline bool need_resched(void)
{
        return unlikely(tif_need_resched());
}

/*
 * Thread group CPU time accounting.
 */
void thread_group_cputime(struct task_struct *tsk, struct task_cputime *times);
void thread_group_cputimer(struct task_struct *tsk, struct task_cputime *times);

/*
 * Reevaluate whether the task has signals pending delivery.
 * Wake the task if so.
 * This is required every time the blocked sigset_t changes.
 * callers must hold sighand->siglock.
 */
extern void recalc_sigpending_and_wake(struct task_struct *t);
extern void recalc_sigpending(void);

extern void signal_wake_up_state(struct task_struct *t, unsigned int state);

static inline void signal_wake_up(struct task_struct *t, bool resume)
{
        signal_wake_up_state(t, resume ? TASK_WAKEKILL : 0);
}
static inline void ptrace_signal_wake_up(struct task_struct *t, bool resume)
{
        signal_wake_up_state(t, resume ? __TASK_TRACED : 0);
}

/*
 * Wrappers for p->thread_info->cpu access. No-op on UP.
 */
#ifdef CONFIG_SMP

static inline unsigned int task_cpu(const struct task_struct *p)
{
#ifdef CONFIG_THREAD_INFO_IN_TASK
        return p->cpu;
#else
        return task_thread_info(p)->cpu;
#endif
}

static inline int task_node(const struct task_struct *p)
{
        return cpu_to_node(task_cpu(p));
}

extern void set_task_cpu(struct task_struct *p, unsigned int cpu);

#else

static inline unsigned int task_cpu(const struct task_struct *p)
{
        return 0;
}

static inline void set_task_cpu(struct task_struct *p, unsigned int cpu)
{
}

#endif /* CONFIG_SMP */

/*
 * In order to reduce various lock holder preemption latencies provide an
 * interface to see if a vCPU is currently running or not.
 *
 * This allows us to terminate optimistic spin loops and block, analogous to
 * the native optimistic spin heuristic of testing if the lock owner task is
 * running or not.
 */
#ifndef vcpu_is_preempted
# define vcpu_is_preempted(cpu) false
#endif

extern long sched_setaffinity(pid_t pid, const struct cpumask *new_mask);
extern long sched_getaffinity(pid_t pid, struct cpumask *mask);

#ifdef CONFIG_CGROUP_SCHED
extern struct task_group root_task_group;
#endif /* CONFIG_CGROUP_SCHED */

extern int task_can_switch_user(struct user_struct *up,
                                        struct task_struct *tsk);

#ifdef CONFIG_TASK_XACCT
static inline void add_rchar(struct task_struct *tsk, ssize_t amt)
{
        tsk->ioac.rchar += amt;
}

static inline void add_wchar(struct task_struct *tsk, ssize_t amt)
{
        tsk->ioac.wchar += amt;
}

static inline void inc_syscr(struct task_struct *tsk)
{
        tsk->ioac.syscr++;
}

static inline void inc_syscw(struct task_struct *tsk)
{
        tsk->ioac.syscw++;
}
#else
static inline void add_rchar(struct task_struct *tsk, ssize_t amt)
{
}

static inline void add_wchar(struct task_struct *tsk, ssize_t amt)
{
}

static inline void inc_syscr(struct task_struct *tsk)
{
}

static inline void inc_syscw(struct task_struct *tsk)
{
}
#endif

#ifndef TASK_SIZE_OF
#define TASK_SIZE_OF(tsk)       TASK_SIZE
#endif

#ifdef CONFIG_MEMCG
extern void mm_update_next_owner(struct mm_struct *mm);
#else
static inline void mm_update_next_owner(struct mm_struct *mm)
{
}
#endif /* CONFIG_MEMCG */

static inline unsigned long task_rlimit(const struct task_struct *tsk,
                unsigned int limit)
{
        return READ_ONCE(tsk->signal->rlim[limit].rlim_cur);
}

static inline unsigned long task_rlimit_max(const struct task_struct *tsk,
                unsigned int limit)
{
        return READ_ONCE(tsk->signal->rlim[limit].rlim_max);
}

static inline unsigned long rlimit(unsigned int limit)
{
        return task_rlimit(current, limit);
}

static inline unsigned long rlimit_max(unsigned int limit)
{
        return task_rlimit_max(current, limit);
}

#define SCHED_CPUFREQ_RT        (1U << 0)
#define SCHED_CPUFREQ_DL        (1U << 1)
#define SCHED_CPUFREQ_IOWAIT    (1U << 2)

#define SCHED_CPUFREQ_RT_DL     (SCHED_CPUFREQ_RT | SCHED_CPUFREQ_DL)

#ifdef CONFIG_CPU_FREQ
struct update_util_data {
       void (*func)(struct update_util_data *data, u64 time, unsigned int flags);
};

void cpufreq_add_update_util_hook(int cpu, struct update_util_data *data,
                       void (*func)(struct update_util_data *data, u64 time,
                                    unsigned int flags));
void cpufreq_remove_update_util_hook(int cpu);
#endif /* CONFIG_CPU_FREQ */

#endif