Merge branches 'pm-core', 'pm-qos', 'pm-domains' and 'pm-opp'

[linux.git] / kernel / exit.c

diff --git a/kernel/exit.c b/kernel/exit.c
index 8e5e21338b3ad0afcee3d1be18c1d7f2495b5b2c..b67c57faa705d991f87b13e6b17bde64afea9131 100644 (file)
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -55,6 +55,7 @@
 #include <linux/shm.h>
 #include <linux/kcov.h>
 #include <linux/random.h>
+#include <linux/rcuwait.h>
 
 #include <linux/uaccess.h>
 #include <asm/unistd.h>
@@ -282,6 +283,35 @@ struct task_struct *task_rcu_dereference(struct task_struct **ptask)
        return task;
 }
 
+void rcuwait_wake_up(struct rcuwait *w)
+{
+       struct task_struct *task;
+
+       rcu_read_lock();
+
+       /*
+        * Order condition vs @task, such that everything prior to the load
+        * of @task is visible. This is the condition as to why the user called
+        * rcuwait_trywake() in the first place. Pairs with set_current_state()
+        * barrier (A) in rcuwait_wait_event().
+        *
+        *    WAIT                WAKE
+        *    [S] tsk = current   [S] cond = true
+        *        MB (A)              MB (B)
+        *    [L] cond            [L] tsk
+        */
+       smp_rmb(); /* (B) */
+
+       /*
+        * Avoid using task_rcu_dereference() magic as long as we are careful,
+        * see comment in rcuwait_wait_event() regarding ->exit_state.
+        */
+       task = rcu_dereference(w->task);
+       if (task)
+               wake_up_process(task);
+       rcu_read_unlock();
+}
+
 struct task_struct *try_get_task_struct(struct task_struct **ptask)
 {
        struct task_struct *task;
@@ -468,12 +498,12 @@ void mm_update_next_owner(struct mm_struct *mm)
  * Turn us into a lazy TLB process if we
  * aren't already..
  */
-static void exit_mm(struct task_struct *tsk)
+static void exit_mm(void)
 {
-       struct mm_struct *mm = tsk->mm;
+       struct mm_struct *mm = current->mm;
        struct core_state *core_state;
 
-       mm_release(tsk, mm);
+       mm_release(current, mm);
        if (!mm)
                return;
        sync_mm_rss(mm);
@@ -491,7 +521,7 @@ static void exit_mm(struct task_struct *tsk)
 
                up_read(&mm->mmap_sem);
 
-               self.task = tsk;
+               self.task = current;
                self.next = xchg(&core_state->dumper.next, &self);
                /*
                 * Implies mb(), the result of xchg() must be visible
@@ -501,22 +531,22 @@ static void exit_mm(struct task_struct *tsk)
                        complete(&core_state->startup);
 
                for (;;) {
-                       set_task_state(tsk, TASK_UNINTERRUPTIBLE);
+                       set_current_state(TASK_UNINTERRUPTIBLE);
                        if (!self.task) /* see coredump_finish() */
                                break;
                        freezable_schedule();
                }
-               __set_task_state(tsk, TASK_RUNNING);
+               __set_current_state(TASK_RUNNING);
                down_read(&mm->mmap_sem);
        }
        atomic_inc(&mm->mm_count);
-       BUG_ON(mm != tsk->active_mm);
+       BUG_ON(mm != current->active_mm);
        /* more a memory barrier than a real lock */
-       task_lock(tsk);
-       tsk->mm = NULL;
+       task_lock(current);
+       current->mm = NULL;
        up_read(&mm->mmap_sem);
        enter_lazy_tlb(mm, current);
-       task_unlock(tsk);
+       task_unlock(current);
        mm_update_next_owner(mm);
        mmput(mm);
        if (test_thread_flag(TIF_MEMDIE))
@@ -823,7 +853,7 @@ void __noreturn do_exit(long code)
        tsk->exit_code = code;
        taskstats_exit(tsk, group_dead);
 
-       exit_mm(tsk);
+       exit_mm();
 
        if (group_dead)
                acct_process();