Paul E. McKenney [Thu, 17 Jan 2019 18:46:34 +0000 (10:46 -0800)]
linux/torture: Convert to SPDX license identifier
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
[ paulmck: Update .h SPDX format per Joe Perches. ] Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Paul E. McKenney [Thu, 17 Jan 2019 18:39:22 +0000 (10:39 -0800)]
linux/srcu: Convert to SPDX license identifier
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
[ paulmck: Update ,h SPDX format per Joe Perches. ] Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Paul E. McKenney [Thu, 17 Jan 2019 18:36:27 +0000 (10:36 -0800)]
linux/rcutree: Convert to SPDX license identifier
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
[ paulmck: Update .h SPDX format per Joe Perches. ] Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Paul E. McKenney [Thu, 17 Jan 2019 18:34:35 +0000 (10:34 -0800)]
linux/rcutiny: Convert to SPDX license identifier
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
[ paulmck: Update .h SPDX format per Joe Perches. ] Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Paul E. McKenney [Thu, 17 Jan 2019 18:32:48 +0000 (10:32 -0800)]
linux/rcu_sync: Convert to SPDX license identifier
Replace the license boiler plate with a SPDX license identifier.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
[ paulmck: Update .h SPDX format per Joe Perches. ] Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Paul E. McKenney [Thu, 17 Jan 2019 18:31:34 +0000 (10:31 -0800)]
linux/rcu_segcblist: Convert to SPDX license identifier
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
[ paulmck: Update .h SPDX format per Joe Perches. ] Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Paul E. McKenney [Thu, 17 Jan 2019 18:30:40 +0000 (10:30 -0800)]
linux/rcupdate: Convert to SPDX license identifier
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
[ paulmck: Update .h SPDX format per Joe Perches. ] Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Paul E. McKenney [Thu, 17 Jan 2019 18:26:59 +0000 (10:26 -0800)]
linux/rcu_node_tree: Convert to SPDX license identifier
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
[ paulmck: Update .h SPDX comment format per Joe Perches. ] Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Paul E. McKenney [Thu, 17 Jan 2019 18:23:39 +0000 (10:23 -0800)]
rcu/tree: Convert to SPDX license identifier
Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
[ paulmck: Update .h file SPDX comment format per Joe Perches. ] Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Junchang Wang [Thu, 3 Jan 2019 14:24:51 +0000 (22:24 +0800)]
RCU/torture.txt: Remove section MODULE PARAMETERS
The supported module parameters are detailed in both RCU/torture.txt and
admin-guide/kernel-parameters.txt, and the latter is actively maintained.
So this patch removes section MODULE PARAMETERS in torture.txt and
adds a reference to the information in kernel-parameters.txt.
Signed-off-by: Junchang Wang <junchangwang@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
[ paulmck: Add search string. ]
Willy Tarreau [Sat, 29 Dec 2018 18:55:48 +0000 (19:55 +0100)]
MAINTAINERS: Add myself as the maintainer for the nolibc header file(s)
I don't expect too many updates there so I should not become a
bottleneck, and if I become one, it will mean that someone will be
more active than me and will be in a better position than me to take
over maintainership. :-)
Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Willy Tarreau [Sat, 29 Dec 2018 18:04:53 +0000 (19:04 +0100)]
tools headers: Move the nolibc header from rcutorture to tools/include/nolibc/
As suggested by Ingo, this header file might benefit other tools than
just rcutorture. For now it's quite limited, but is easy to extend, so
exposing it into tools/include/nolibc/ will make it much easier to
adopt by other tools.
The mkinitrd.sh script in rcutorture was updated to use this new location.
Cc: Ingo Molnar <mingo@kernel.org> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Willy Tarreau [Sat, 29 Dec 2018 18:02:18 +0000 (19:02 +0100)]
rcutorture/nolibc: Add a bit of documentation to explain how to use nolibc
Ingo rightfully asked for a bit more documentation in the nolibc header,
so this patch adds some explanation about its purpose, how it's made, and
how to use it.
Cc: Ingo Molnar <mingo@kernel.org> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Reviewed-by: Joey Pabalinas <joeypabalinas@gmail.com> Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Willy Tarreau [Sat, 29 Dec 2018 18:02:17 +0000 (19:02 +0100)]
rcutorture/nolibc: Fix some poor indentation and alignment
A few macros had their rightmost backslash misaligned, and the pollfd
struct definition resisted the previous code reindent. Nothing else
changed.
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Reviewed-by: Joey Pabalinas <joeypabalinas@gmail.com>
Willy Tarreau [Sat, 29 Dec 2018 18:02:16 +0000 (19:02 +0100)]
rcutorture/nolibc: Fix the clobbered registers in the MIPS syscall definition
A last-minute checkpatch cleanup caused most of list of clobbered
registers to be lost in the MIPS syscall definition. Although this code
is not yet used on MIPS, it is nevertheless better to fix it before it
does get used.
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Fri, 28 Dec 2018 15:48:43 +0000 (07:48 -0800)]
rcuperf: Stop abusing IS_ENABLED()
The ever-evolving IS_ENABLED() macro is intended for CONFIG_* Kconfig
options, but rcuperf currently uses it for the decidedly non-CONFIG_*
MODULE macro. In the spirit of not inviting trouble, this commit
substitutes tried-and-true #ifdef.
Reported-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Acked-by: Ingo Molnar <mingo@kernel.org>
Paul E. McKenney [Mon, 10 Dec 2018 17:44:52 +0000 (09:44 -0800)]
rcutorture: Add grace period after CPU offline
Beyond a certain point in the CPU-hotplug offline process, timers get
stranded on the outgoing CPU, and won't fire until that CPU comes back
online, which might well be never. This commit therefore adds a hook
in torture_onoff_init() that is invoked from torture_offline(), which
rcutorture uses to occasionally wait for a grace period. This should
result in failures for RCU implementations that rely on stranded timers
eventually firing in the absence of the CPU coming back online.
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
torture: Explain and simplify odd "for" loop in mkinitrd.sh
Why a Bourne-shell "for" loop? And why 192 instances of "a"? This commit
adds a shell comment to present the answer to these mysteries. It also
uses a series of factor-of-four Bourne-shell assignments to make it
easy to see how many instances there are, replacing the earlier wall of
'a' characters.
Reported-by: Josh Triplett <josh@joshtriplett.org> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
[ paulmck: Fix wrong-variable bugs noted by Andrea Parri. ]
rcutorture: Record grace periods in forward-progress histogram
This commit records grace periods in rcutorture's n_launders_hist[]
histogram, thus allowing rcu_torture_fwd_cb_hist() to print out the
elapsed number of grace periods between buckets. This information
helps to determine whether a lack of forward progress is due to stalled
grace periods on the one hand or due to sluggish callback invocation on
the other.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
srcu_queue_delayed_work_on() disables preemption (and therefore CPU
hotplug in RCU's case) and then checks based on its own accounting if a
CPU is online. If the CPU is online it uses queue_delayed_work_on()
otherwise it fallbacks to queue_delayed_work().
The problem here is that queue_work() on -RT does not work with disabled
preemption.
queue_work_on() works also on an offlined CPU. queue_delayed_work_on()
has the problem that it is possible to program a timer on an offlined
CPU. This timer will fire once the CPU is online again. But until then,
the timer remains programmed and nothing will happen.
Add a local timer which will fire (as requested per delay) on the local
CPU and then enqueue the work on the specific CPU.
RCUtorture testing with SRCU-P for 24h showed no problems.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Fri, 30 Nov 2018 18:06:46 +0000 (10:06 -0800)]
srcu: Check for invalid idx argument in srcu_read_unlock()
The current SRCU implementation has an idx argument of zero or one,
and never anything else. This commit therefore adds a WARN_ON_ONCE()
to complain if this restriction is violated.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
lockdep_assert_held() is better suited to checking locking requirements,
since it only checks if the current thread holds the lock regardless of
whether someone else does. This is also a step towards possibly removing
spin_is_locked().
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: "Radim Krčmář" <rkrcmar@redhat.com> Cc: <kvm@vger.kernel.org> Acked-by: Paolo Bonzini <pbonzini@redhat.com>
The WARN_ON_SMP() comment header suggests using spin_is_locked() to
check for locks being held. But these days we prefer lockdep_assert_held(),
so this commit removes that suggestion.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: <linux-arch@vger.kernel.org>
The rcu_assign_pointer() function currently doesn't do any sparse checking
on the assigned-to pointer. So its possible that a pointer that is
not __rcu annotated is assigned with rcu_assign_pointer without sparse
complaints. Because rcu_dereference() already does such checking,
this commit makes rcu_assign_pointer() to do the same. The extra
error could be helpful in cases where an RCU pointer is assigned with
rcu_assign_pointer() but not annotated with __rcu.
This doesn't generate any code in the normal case because __CHECKER__ is
defined only in the context of sparse.
This commit also renames rcu_dereference_sparse() to rcu_check_parse()
since the checking now happens not only during derereferencing but also
during assignment.
Test: Introduced an rcu_assign_pointer in code and checked the output of
sparse with and without this change. The change correctly causes sparse
to throw an error.
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Mon, 26 Nov 2018 19:12:39 +0000 (11:12 -0800)]
rcu: Remove preemption disabling from expedited CPU selection
It turns out that it is queue_delayed_work_on() rather than
queue_work_on() that has difficulties when used concurrently with
CPU-hotplug removal operations. It is therefore unnecessary to protect
CPU identification and queue_work_on() with preempt_disable().
This commit therefore removes the preempt_disable() and preempt_enable()
from sync_rcu_exp_select_cpus(), which has the further benefit of reducing
the number of changes that must be maintained in the -rt patchset.
Reported-by: Thomas Gleixner <tglx@linutronix.de> Reported-by: Sebastian Siewior <bigeasy@linutronix.de> Suggested-by: Boqun Feng <boqun.feng@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Wed, 21 Nov 2018 20:42:12 +0000 (12:42 -0800)]
rcu: Rename rcu_process_callbacks() to rcu_core() for Tree RCU
Although the name rcu_process_callbacks() still makes sense for Tiny
RCU, where most of what it does is invoke callbacks, it no longer makes
much sense for Tree RCU, especially given that the actually callback
invocation is relegated to rcu_do_batch(), or, for no-CBs CPUs, to the
rcuo kthreads. Especially in the latter case, rcu_process_callbacks()
has very little to do with actual callbacks. A better description of
this function is that it performs RCU's core processing.
This commit therefore changes the name of Tree RCU's rcu_process_callbacks()
function to rcu_core(), which also has the virtue of being consistent with
the existing invoke_rcu_core() function.
While in the area, the header comment is reworked.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Wed, 21 Nov 2018 19:35:03 +0000 (11:35 -0800)]
rcu: Rename rcu_check_callbacks() to rcu_sched_clock_irq()
The name rcu_check_callbacks() arguably made sense back in the early
2000s when RCU was quite a bit simpler than it is today, but it has
become quite misleading, especially with the advent of dyntick-idle
and NO_HZ_FULL. The rcu_check_callbacks() function is RCU's hook into
the scheduling-clock interrupt, and is now but one of many ways that
callbacks get promoted to invocable state.
This commit therefore changes the name to rcu_sched_clock_irq(),
which is the same number of characters and clearly indicates this
function's relation to the rest of the Linux kernel. In addition, for
the sake of consistency, rcu_flavor_check_callbacks() is also renamed
to rcu_flavor_sched_clock_irq().
While in the area, the header comments for both functions are reworked.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Tue, 11 Dec 2018 16:28:56 +0000 (08:28 -0800)]
doc: CPU-hotplug notifiers cannot invoke synchronize_srcu() or srcu_barrier()
SRCU's synchronize_srcu() may not be invoked from CPU-hotplug notifiers,
due to the fact that SRCU grace periods make use of timers and the
possibility of timers being temporarily stranded on the outgoing CPU.
This stranding of timers means that timers posted to the outgoing CPU
will not fire until late in the CPU-hotplug process. The problem is
that if a notifier is waiting on an SRCU grace period, that grace period
is waiting on a timer, and that timer is stranded on the outgoing CPU,
then the notifier will never be awakened, in other words, deadlock has
occurred. This same situation of course also prohibits srcu_barrier()
from being invoked from CPU-hotplug notifiers.
This commit therefore updates the requirements to include this restriction.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Tue, 20 Nov 2018 18:22:00 +0000 (10:22 -0800)]
doc: Now jiffies_till_sched_qs solicits help from cond_resched()
The rcutree.jiffies_till_sched_qs kernel boot parameter used to solicit
help only from rcu_note_context_switch(), but now also solicits help
from cond_resched(). This commit therefore updates kernel-parameters.txt
accordingly.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Zhang, Jun [Wed, 19 Dec 2018 18:37:34 +0000 (10:37 -0800)]
rcu: Prevent needless ->gp_seq_needed update in __note_gp_changes()
Currently, __note_gp_changes() checks to see if the rcu_node structure's
->gp_seq_needed is greater than or equal to that of the rcu_data
structure, and if so, updates the rcu_data structure's ->gp_seq_needed
field. This results in a useless store in the case where the two fields
are equal.
This commit therefore carries out this store only in the case where the
rcu_node structure's ->gp_seq_needed is strictly greater than that of
the rcu_data structure.
Zhang, Jun [Tue, 18 Dec 2018 14:55:01 +0000 (06:55 -0800)]
rcu: Do RCU GP kthread self-wakeup from softirq and interrupt
The rcu_gp_kthread_wake() function is invoked when it might be necessary
to wake the RCU grace-period kthread. Because self-wakeups are normally
a useless waste of CPU cycles, if rcu_gp_kthread_wake() is invoked from
this kthread, it naturally refuses to do the wakeup.
Unfortunately, natural though it might be, this heuristic fails when
rcu_gp_kthread_wake() is invoked from an interrupt or softirq handler
that interrupted the grace-period kthread just after the final check of
the wait-event condition but just before the schedule() call. In this
case, a wakeup is required, even though the call to rcu_gp_kthread_wake()
is within the RCU grace-period kthread's context. Failing to provide
this wakeup can result in grace periods failing to start, which in turn
results in out-of-memory conditions.
This race window is quite narrow, but it actually did happen during real
testing. It would of course need to be fixed even if it was strictly
theoretical in nature.
This patch does not Cc stable because it does not apply cleanly to
earlier kernel versions.
Fixes: 48a7639ce80c ("rcu: Make callers awaken grace-period kthread") Reported-by: "He, Bo" <bo.he@intel.com> Co-developed-by: "Zhang, Jun" <jun.zhang@intel.com> Co-developed-by: "He, Bo" <bo.he@intel.com> Co-developed-by: "xiao, jin" <jin.xiao@intel.com> Co-developed-by: Bai, Jie A <jie.a.bai@intel.com>
Signed-off: "Zhang, Jun" <jun.zhang@intel.com>
Signed-off: "He, Bo" <bo.he@intel.com>
Signed-off: "xiao, jin" <jin.xiao@intel.com>
Signed-off: Bai, Jie A <jie.a.bai@intel.com> Signed-off-by: "Zhang, Jun" <jun.zhang@intel.com>
[ paulmck: Switch from !in_softirq() to "!in_interrupt() &&
!in_serving_softirq() to avoid redundant wakeups and to also handle the
interrupt-handler scenario as well as the softirq-handler scenario that
actually occurred in testing. ] Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Link: https://lkml.kernel.org/r/CD6925E8781EFD4D8E11882D20FC406D52A11F61@SHSMSX104.ccr.corp.intel.com
Paul E. McKenney [Wed, 12 Dec 2018 20:32:06 +0000 (12:32 -0800)]
rcu: Add sysrq rcu_node-dump capability
Life is hard if RCU manages to get stuck without triggering RCU CPU
stall warnings or triggering the rcu_check_gp_start_stall() checks
for failing to start a grace period. This commit therefore adds a
boot-time-selectable sysrq key (commandeering "y") that allows manually
dumping Tree RCU state. The new rcutree.sysrq_rcu kernel boot parameter
must be set for this sysrq to be available.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Wed, 12 Dec 2018 15:20:07 +0000 (07:20 -0800)]
rcu: Protect rcu_check_gp_kthread_starvation() access to ->gp_flags
The rcu_check_gp_kthread_starvation() function can be invoked without
holding locks, so the access to the rcu_state structure's ->gp_flags
field must be protected with READ_ONCE(). This commit therefore adds
this protection.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Tue, 11 Dec 2018 00:09:49 +0000 (16:09 -0800)]
rcu: Improve diagnostics for failed RCU grace-period start
If a grace period fails to start (for example, because you commented
out the last two lines of rcu_accelerate_cbs_unlocked()), rcu_core()
will invoke rcu_check_gp_start_stall(), which will notice and complain.
However, this complaint is lacking crucial debugging information such
as when the last wakeup executed and what the value of ->gp_seq was at
that time. This commit therefore removes the current pr_alert() from
rcu_check_gp_start_stall(), instead invoking show_rcu_gp_kthreads(),
which has been updated to print the needed information, which is collected
by rcu_gp_kthread_wake().
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Given that RCU has a perfectly good per-CPU rcu_data structure, most
per-CPU quantities should be stored there.
This commit therefore moves the rcu_cpu_has_work per-CPU variable to
the rcu_data structure. This also makes this variable unconditionally
present, which should be acceptable given the memory reduction due to the
RCU flavor consolidation and also due to simplifications this will enable.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
rcu: Move rcu_cpu_kthread_status to rcu_data structure
Given that RCU has a perfectly good per-CPU rcu_data structure, most
per-CPU quantities should be stored there.
This commit therefore moves the rcu_cpu_kthread_status per-CPU variable
to the rcu_data structure. This also makes this variable unconditionally
present, which should be acceptable given the memory reduction due to the
RCU flavor consolidation and also due to simplifications this will enable.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
rcu: Move rcu_cpu_kthread_task to rcu_data structure
Given that RCU has a perfectly good per-CPU rcu_data structure, most
per-CPU quantities should be stored there.
This commit therefore moves the rcu_cpu_kthread_task per-CPU variable to
the rcu_data structure. This also makes this variable unconditionally
present, which should be acceptable given the memory reduction due to the
RCU flavor consolidation and also due to simplifications this will enable.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Tue, 20 Nov 2018 18:43:34 +0000 (10:43 -0800)]
rcu: Accommodate zero jiffies_till_first_fqs and kthread kicking
It is perfectly fine to set the rcutree.jiffies_till_first_fqs boot
parameter to zero, in fact, this can be useful on specialty systems that
usually have at least one idle CPU and that need fast grace periods.
This is because this setting causes the RCU grace-period kthread to
scan for idle threads immediately after grace-period initialization,
as opposed to waiting several jiffies to do so.
It is also perfectly fine to set the rcutree.rcu_kick_kthreads kernel
parameter, which gives the RCU grace-period kthread an extra wakeup
if it doesn't make progress for a period of three times the setting of
the rcutree.jiffies_till_first_fqs boot parameter. This is of course
problematic when the value of this parameter is zero, as it can result
in unnecessary wakeup IPIs along with unnecessary WARN_ONCE() invocations.
This commit therefore defers kthread kicking for at least two jiffies,
regardless of the setting of rcutree.jiffies_till_first_fqs.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
rcu: Remove wrapper definitions for obsolete RCU update functions
None of synchronize_rcu_bh, synchronize_rcu_bh_expedited, call_rcu_bh,
rcu_barrier_bh, synchronize_sched, synchronize_sched_expedited,
call_rcu_sched, rcu_barrier_sched, get_state_synchronize_sched, and
cond_synchronize_sched are actually used. This commit therefore removes
their trivial wrapper-function definitions.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Thu, 29 Nov 2018 21:28:49 +0000 (13:28 -0800)]
rcu: Discard separate per-CPU callback counts
Back when there were multiple flavors of RCU, it was necessary to
separately count lazy and non-lazy callbacks for each CPU. These counts
were used in CONFIG_RCU_FAST_NO_HZ kernels to determine how long a newly
idle CPU should be allowed to sleep before handling its RCU callbacks.
But now that there is only one flavor, the callback counts for a given
CPU's sole rcu_data structure are the counts for that CPU.
This commit therefore removes the rcu_data structure's ->nonlazy_posted
and ->nonlazy_posted_snap fields, the rcu_idle_count_callbacks_posted()
and rcu_cpu_has_callbacks() functions, repurposes the rcu_data structure's
->all_lazy field to record the laziness state at the beginning of the
latest idle sojourn, and modifies CONFIG_RCU_FAST_NO_HZ RCU CPU stall
warnings accordingly.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Thu, 29 Nov 2018 19:50:04 +0000 (11:50 -0800)]
rcu: Inline _synchronize_rcu_expedited() into synchronize_rcu_expedited()
Now that _synchronize_rcu_expedited() has only one caller, and given that
this is a tail call, this commit inlines _synchronize_rcu_expedited()
into synchronize_rcu_expedited().
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Thu, 29 Nov 2018 18:42:06 +0000 (10:42 -0800)]
rcu: Consolidate PREEMPT and !PREEMPT synchronize_rcu()
Now that rcu_blocking_is_gp() makes the correct immediate-return
decision for both PREEMPT and !PREEMPT, a single implementation of
synchronize_rcu() will work correctly under both configurations.
This commit therefore eliminates a few lines of code by consolidating
the two implementations of synchronize_rcu().
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Thu, 29 Nov 2018 18:01:52 +0000 (10:01 -0800)]
rcu: Consolidate PREEMPT and !PREEMPT synchronize_rcu_expedited()
The CONFIG_PREEMPT=n and CONFIG_PREEMPT=y implementations of
synchronize_rcu_expedited() are quite similar, and with small
modifications to rcu_blocking_is_gp() can be made identical. This commit
therefore makes this change in order to save a few lines of code and to
reduce the amount of duplicate code.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Thu, 29 Nov 2018 17:15:54 +0000 (09:15 -0800)]
rcu: Determine expedited-GP IPI handler at build time
Back when there could be multiple RCU flavors running in the same kernel
at the same time, it was necessary to specify the expedited grace-period
IPI handler at runtime. Now that there is only one RCU flavor, the
IPI handler can be determined at build time. There is therefore no
longer any reason for the RCU-preempt and RCU-sched IPI handlers to
have different names, nor is there any reason to pass these handlers in
function arguments and in the data structures enclosing workqueues.
This commit therefore makes all these changes, pushing the specification
of the expedited grace-period IPI handler down to the point of use.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Thu, 29 Nov 2018 01:02:44 +0000 (17:02 -0800)]
rcu: Inline rcu_kthread_do_work() into its sole remaining caller
The rcu_kthread_do_work() function has a single-line body and only one
remaining caller. This commit therefore saves a few lines of code by
inlining rcu_kthread_do_work() into its sole remaining caller.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Thu, 29 Nov 2018 00:59:50 +0000 (16:59 -0800)]
rcu: Eliminate RCU_BH_FLAVOR and RCU_SCHED_FLAVOR
Now that the RCU flavors have been consolidated, RCU_BH_FLAVOR and
RCU_SCHED_FLAVOR are no longer used. This commit therefore saves a
few lines by removing them.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Thu, 29 Nov 2018 00:57:54 +0000 (16:57 -0800)]
rcu: Inline force_quiescent_state() into rcu_force_quiescent_state()
Given that rcu_force_quiescent_state() is a simple wrapper around
force_quiescent_state(), this commit saves a few lines of code by
inlining force_quiescent_state() into rcu_force_quiescent_state(),
and changing all references to force_quiescent_state() to instead
invoke rcu_force_quiescent_state().
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Wed, 28 Nov 2018 18:37:42 +0000 (10:37 -0800)]
rcu: Make expedited IPI handler return after handling critical section
During expedited RCU grace-period initialization, IPIs are sent to
all non-idle online CPUs. The IPI handler checks to see if the CPU is
in quiescent state, reporting one if so. This handler looks at three
different cases: (1) The CPU is not in an rcu_read_lock()-based critical
section, (2) The CPU is in the process of exiting an rcu_read_lock()-based
critical section, and (3) The CPU is in an rcu_read_lock()-based critical
section. In case (2), execution falls through into case (3).
This is harmless from a functionality viewpoint, but can result in
needless overhead during an improbable corner case. This commit therefore
adds the "return" statement needed to prevent fall-through.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
Paul E. McKenney [Tue, 27 Nov 2018 21:55:53 +0000 (13:55 -0800)]
rcu: Rename and comment changes due to only one rcuo kthread per CPU
Given RCU flavor consolidation, the name rcu_spawn_all_nocb_kthreads()
is quite misleading. It no longer ever creates more than one kthread,
and it does so only for the specified CPU. This commit therefore changes
this name to the more descriptive rcu_spawn_cpu_nocb_kthread(), and also
fixes up a similar issue in its header comment while in the area.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
sched: Replace synchronize_sched() with synchronize_rcu()
Now that synchronize_rcu() waits for preempt-disable regions of
code as well as RCU read-side critical sections, synchronize_sched()
can be replaced by synchronize_rcu(), in fact, synchronize_sched()
is now completely equivalent to synchronize_rcu(). This commit
therefore replaces synchronize_sched() with synchronize_rcu() so that
synchronize_sched() can eventually be removed entirely.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org>
Now that call_rcu()'s callback is not invoked until after all
preempt-disable regions of code have completed (in addition to explicitly
marked RCU read-side critical sections), call_rcu() can be used in place
of call_rcu_sched(). This commit therefore makes that change.
While in the area, this commit also updates an outdated header comment
for for_each_domain().
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org>
tools/memory-model: Make scripts take "-j" abbreviation for "--jobs"
The "--jobs" argument to the litmus-test scripts is similar to the "-jN"
argument to "make", so this commit allows the "-jN" form as well. While
in the area, it also prohibits the various forms of "-j0".
Suggested-by: Alan Stern <stern@rowland.harvard.edu> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: akiyks@gmail.com Cc: boqun.feng@gmail.com Cc: dhowells@redhat.com Cc: j.alglave@ucl.ac.uk Cc: linux-arch@vger.kernel.org Cc: luc.maranget@inria.fr Cc: npiggin@gmail.com Cc: parri.andrea@gmail.com Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/20181203230451.28921-3-paulmck@linux.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
tools/memory-model: Add scripts to check github litmus tests
The https://github.com/paulmckrcu/litmus repository contains a large
number of C-language litmus tests that include "Result:" comments
predicting the verification result. This commit adds a number of scripts
that run tests on these litmus tests:
checkghlitmus.sh:
Runs all litmus tests in the https://github.com/paulmckrcu/litmus
archive that are C-language and that have "Result:" comment lines
documenting expected results, comparing the actual results to
those expected. Clones the repository if it has not already
been cloned into the "tools/memory-model/litmus" directory.
initlitmushist.sh
Run all litmus tests having no more than the specified number
of processes given a specified timeout, recording the results in
.litmus.out files. Clones the repository if it has not already
been cloned into the "tools/memory-model/litmus" directory.
newlitmushist.sh
For all new or updated litmus tests having no more than the
specified number of processes given a specified timeout, run
and record the results in .litmus.out files.
checklitmushist.sh
Run all litmus tests having .litmus.out files from previous
initlitmushist.sh or newlitmushist.sh runs, comparing the
herd output to that of the original runs.
The above scripts will run litmus tests concurrently, by default with
one job per available CPU. Giving any of these scripts the --help
argument will cause them to print usage information.
This commit also adds a number of helper scripts that are not intended
to be invoked from the command line:
cmplitmushist.sh: Compare the output of two different runs of the same
litmus test.
judgelitmus.sh: Compare the output of a litmus test to its "Result:"
comment line.
parseargs.sh: Parse command-line arguments.
runlitmushist.sh: Run the litmus tests whose pathnames are provided one
per line on standard input.
While in the area, this commit also makes the existing checklitmus.sh
and checkalllitmus.sh scripts use parseargs.sh in order to provide a
bit of uniformity. In addition, per-litmus-test status output is directed
to stdout, while end-of-test summary information is directed to stderr.
Finally, the error flag standardizes on "!!!" to assist those familiar
with rcutorture output.
The defaults for the parseargs.sh arguments may be overridden by using
environment variables: LKMM_DESTDIR for --destdir, LKMM_HERD_OPTIONS
for --herdoptions, LKMM_JOBS for --jobs, LKMM_PROCS for --procs, and
LKMM_TIMEOUT for --timeout.
[ paulmck: History-check summary-line changes per Alan Stern feedback. ] Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: akiyks@gmail.com Cc: boqun.feng@gmail.com Cc: dhowells@redhat.com Cc: j.alglave@ucl.ac.uk Cc: linux-arch@vger.kernel.org Cc: luc.maranget@inria.fr Cc: npiggin@gmail.com Cc: parri.andrea@gmail.com Cc: stern@rowland.harvard.edu Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/20181203230451.28921-2-paulmck@linux.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Andrea Parri [Mon, 3 Dec 2018 23:04:49 +0000 (15:04 -0800)]
tools/memory-model: Model smp_mb__after_unlock_lock()
The kernel documents smp_mb__after_unlock_lock() the following way:
"Place this after a lock-acquisition primitive to guarantee that
an UNLOCK+LOCK pair acts as a full barrier. This guarantee applies
if the UNLOCK and LOCK are executed by the same CPU or if the
UNLOCK and LOCK operate on the same lock variable."
Formalize in LKMM the above guarantee by defining (new) mb-links according
to the law:
where the component ([UL] ; co ; [LKW]) identifies "UNLOCK+LOCK pairs on
the same lock variable" and the component ([UL] ; po ; [LKW]) identifies
"UNLOCK+LOCK pairs executed by the same CPU".
In particular, the LKMM forbids the following two behaviors (the second
litmus test below is based on:
Linus Torvalds [Fri, 18 Jan 2019 05:17:20 +0000 (17:17 +1200)]
Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma
Pull rdma fixes frfom Jason Gunthorpe:
"Not much so far. We have the usual batch of bugs and two fixes to code
merged this cycle:
- Restore valgrind support for the ioctl verbs interface merged this
window, and fix a missed error code on an error path from that
conversion
- A user reported crash on obsolete mthca hardware
- pvrdma was using the wrong command opcode toward the hypervisor
- NULL pointer crash regression when dumping rdma-cm over netlink
- Be conservative about exposing the global rkey"
* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma:
RDMA/uverbs: Mark ioctl responses with UVERBS_ATTR_F_VALID_OUTPUT
RDMA/mthca: Clear QP objects during their allocation
RDMA/vmw_pvrdma: Return the correct opcode when creating WR
RDMA/cma: Add cm_id restrack resource based on kernel or user cm_id type
RDMA/nldev: Don't expose unsafe global rkey to regular user
RDMA/uverbs: Fix post send success return value in case of error
Linus Torvalds [Fri, 18 Jan 2019 05:14:02 +0000 (17:14 +1200)]
Merge tag 'drm-fixes-2019-01-18' of git://anongit.freedesktop.org/drm/drm
Pull drm fixes from Dave Airlie:
"The rc3 fixes are a bit scattered:
- meson, sun4i and rockchip all had missing of_node_put.
- qxl and virtio both were advertising dma-buf to userspace when they
really shouldn't have.
Otherwise:
meson:
- modesetting regression fix
i915 GVT:
- one cmd parser failure fix
- region cleanup fix in vGPU destroy
amdgpu:
- KFD fixes for arm64 mixed APU/DGPU
- vega12 powerplay fix
- raven DC fixes
- freesync fix"
* tag 'drm-fixes-2019-01-18' of git://anongit.freedesktop.org/drm/drm:
drm/amd/display: Detach backlight from stream
drm/sun4i: backend: add missing of_node_puts
Revert "drm/amdgpu: validate user pitch alignment"
Revert "drm/amdgpu: validate user GEM object size"
drm/meson: Fix atomic mode switching regression
drm/i915/gvt: Fix mmap range check
drm/i915/gvt: free VFIO region space in vgpu detach
drm/amd/display: Fix disabled cursor on top screen edge
drm/amd/display: fix warning on raven hotplug
drm/amd/display: fix PME notification not working in RV desktop
drm/amd/display: Only get the connector state for VRR when toggled
drm/amd/display: Pack DMCU iRAM alignment
drm/amd/powerplay: run acg btc for Vega12
drm/amdkfd: Don't assign dGPUs to APU topology devices
drm/amdkfd: Allow building KFD on ARM64 (v2)
drm/meson: add missing of_node_put
drm/virtio: drop prime import/export callbacks
drm/qxl: drop prime import/export callbacks
drm/i915/gvt: Allow F_CMD_ACCESS on mmio 0x21f0
drm/rockchip: add missing of_node_put
Linus Torvalds [Fri, 18 Jan 2019 04:58:07 +0000 (16:58 +1200)]
Merge tag 'led-fix-for-5.0-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds
Pull LED fix from Jacek Anaszewski.
* tag 'led-fix-for-5.0-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/j.anaszewski/linux-leds:
leds: lp5523: fix a missing check of return value of lp55xx_read
Linus Torvalds [Fri, 18 Jan 2019 04:55:49 +0000 (16:55 +1200)]
Merge tag 'hwmon-for-v5.0-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging
Pull hwmon fixes from Guenter Roeck:
"Minor fixes/regressions"
* tag 'hwmon-for-v5.0-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
hwmon: (tmp421) Correct the misspelling of the tmp442 compatible attribute in OF device ID table
hwmon: (occ) Fix potential integer overflow
hwmon: (lm80) Fix missing unlock on error in set_fan_div()
hwmon: (nct6775) Enable IO mapping for NCT6797D and NCT6798D
hwmon: (nct6775) Fix chip ID for NCT6798D
Dave Airlie [Thu, 17 Jan 2019 23:14:34 +0000 (09:14 +1000)]
Merge tag 'drm-misc-fixes-2019-01-17' of git://anongit.freedesktop.org/drm/drm-misc into drm-fixes
drm-misc-fixes for v5.0-rc3:
- Add missing calls to of_node_put to sun4i, meson, and rockchip.
- Drop unimplemented prime callbacks in virtio and qxl, so support
for prime is not advertised on those drivers.
- Fix mode switching regression in meson.
Dave Airlie [Thu, 17 Jan 2019 23:12:39 +0000 (09:12 +1000)]
Merge tag 'drm-intel-fixes-2019-01-17' of git://anongit.freedesktop.org/drm/drm-intel into drm-fixes
drm/i915/gvt fixes for v5.0-rc3
"This contains one cmd parser failure fix to allow cmd access for one
register, and fix region cleanup properly in vGPU destroy, and another
fix for critical mmap size check mistake."
Linus Torvalds [Thu, 17 Jan 2019 18:27:24 +0000 (06:27 +1200)]
Merge tag 'afs-fixes-20190117' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs
Pull AFS fixes from David Howells:
"Here's a set of fixes for AFS:
- Use struct_size() for kzalloc() size calculation.
- When calling YFS.CreateFile rather than AFS.CreateFile, it is
possible to create a file with a file lock already held. The
default value indicating no lock required is actually -1, not 0.
- Fix an oops in inode/vnode validation if the target inode doesn't
have a server interest assigned (ie. a server that will notify us
of changes by third parties).
- Fix refcounting of keys in file locking.
- Fix a race in refcounting asynchronous operations in the event of
an error during request transmission. The provision of a dedicated
function to get an extra ref on a call is split into a separate
commit"
* tag 'afs-fixes-20190117' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
afs: Fix race in async call refcounting
afs: Provide a function to get a ref on a call
afs: Fix key refcounting in file locking code
afs: Don't set vnode->cb_s_break in afs_validate()
afs: Set correct lock type for the yfs CreateFile
afs: Use struct_size() in kzalloc()
Linus Torvalds [Thu, 17 Jan 2019 18:22:08 +0000 (06:22 +1200)]
Merge branch 'stable/for-linus-5.0' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb
Pull swiotlb fix from Konrad Rzeszutek Wilk:
"A tiny fix for v5.0-rc2:
This fixes an issue with GPU cards not working anymore with the DMA
mapping work Christopher did - as the SWIOTLB is initialized first and
then free'd (as IOMMU is available) but we forgot to clear our start
and end entries which are used and BOOM"
* 'stable/for-linus-5.0' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/swiotlb:
swiotlb: clear io_tlb_start and io_tlb_end in swiotlb_exit
David Howells [Thu, 10 Jan 2019 15:40:50 +0000 (15:40 +0000)]
afs: Fix race in async call refcounting
There's a race between afs_make_call() and afs_wake_up_async_call() in the
case that an error is returned from rxrpc_kernel_send_data() after it has
queued the final packet.
afs_make_call() will try and clean up the mess, but the call state may have
been moved on thereby causing afs_process_async_call() to also try and to
delete the call.
Fix this by:
(1) Getting an extra ref for an asynchronous call for the call itself to
hold. This makes sure the call doesn't evaporate on us accidentally
and will allow the call to be retained by the caller in a future
patch. The ref is released on leaving afs_make_call() or
afs_wait_for_call_to_complete().
(2) In the event of an error from rxrpc_kernel_send_data():
(a) Don't set the call state to AFS_CALL_COMPLETE until *after* the
call has been aborted and ended. This prevents
afs_deliver_to_call() from doing anything with any notifications
it gets.
(b) Explicitly end the call immediately to prevent further callbacks.
(c) Cancel any queued async_work and wait for the work if it's
executing. This allows us to be sure the race won't recur when we
change the state. We put the work queue's ref on the call if we
managed to cancel it.
(d) Put the call's ref that we got in (1). This belongs to us as long
as the call is in state AFS_CALL_CL_REQUESTING.
Fixes: 341f741f04be ("afs: Refcount the afs_call struct") Signed-off-by: David Howells <dhowells@redhat.com>
David Howells [Wed, 9 Jan 2019 17:23:54 +0000 (17:23 +0000)]
afs: Fix key refcounting in file locking code
Fix the refcounting of the authentication keys in the file locking code.
The vnode->lock_key member points to a key on which it expects to be
holding a ref, but it isn't always given an extra ref, however.
Fixes: 0fafdc9f888b ("afs: Fix file locking") Signed-off-by: David Howells <dhowells@redhat.com>
Marc Dionne [Wed, 9 Jan 2019 17:23:54 +0000 (17:23 +0000)]
afs: Don't set vnode->cb_s_break in afs_validate()
A cb_interest record is not necessarily attached to the vnode on entry to
afs_validate(), which can cause an oops when we try to bring the vnode's
cb_s_break up to date in the default case (ie. no current callback promise
and the vnode has not been deleted).
Fix this by simply removing the line, as vnode->cb_s_break will be set when
needed by afs_register_server_cb_interest() when we next get a callback
promise from RPC call.
Masahiro Yamada [Tue, 15 Jan 2019 07:19:00 +0000 (16:19 +0900)]
kbuild: mark prepare0 as PHONY to fix external module build
Commit c3ff2a5193fa ("powerpc/32: add stack protector support")
caused kernel panic on PowerPC when an external module is used with
CONFIG_STACKPROTECTOR because the 'prepare' target was not executed
for the external module build.
Commit e07db28eea38 ("kbuild: fix single target build for external
module") turned it into a build error because the 'prepare' target is
now executed but the 'prepare0' target is missing for the external
module build.
External module on arm/arm64 with CONFIG_STACKPROTECTOR_PER_TASK is
also broken in the same way.
Move 'PHONY += prepare0' to the common place. GNU Make is fine with
missing rule for phony targets. I also removed the comment which is
wrong irrespective of this commit.
I minimize the change so it can be easily backported to 4.20.x
To fix v4.20, please backport e07db28eea38 ("kbuild: fix single target
build for external module"), and then this commit.
Linus Torvalds [Thu, 17 Jan 2019 04:54:58 +0000 (16:54 +1200)]
Merge branch 'fixes-v5.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
Pull security subsystem fixes from James Morris:
"Fixes for the security subsystem.
The first (by Casey actually - it's misattributed) fixes a regression
introduced with the LSM stacking changes"
* 'fixes-v5.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
LSM: Check for NULL cred-security on free
Yama: Check for pid death before checking ancestry
seccomp: fix UAF in user-trap code
James Morris [Wed, 16 Jan 2019 23:41:11 +0000 (15:41 -0800)]
LSM: Check for NULL cred-security on free
From: Casey Schaufler <casey@schaufler-ca.com>
Check that the cred security blob has been set before trying
to clean it up. There is a case during credential initialization
that could result in this.
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com> Acked-by: John Johansen <john.johansen@canonical.com> Signed-off-by: James Morris <james.morris@microsoft.com> Reported-by: syzbot+69ca07954461f189e808@syzkaller.appspotmail.com
David Francis [Tue, 20 Nov 2018 14:42:58 +0000 (09:42 -0500)]
drm/amd/display: Detach backlight from stream
[Why]
Backlight is conceptually a property of links, not streams.
All backlight programming is done on links, but there is a
stream property bl_pwm_level that is used to restore backlight
on dpms on and s3 resume. This is unnecessary, as backlight
is already restored by hardware with no driver intervention.
[How]
Remove bl_pwm_level, and the stream argument to set_backlight
Bug: https://bugs.freedesktop.org/show_bug.cgi?id=109375 Signed-off-by: David Francis <David.Francis@amd.com> Reviewed-by: Harry Wentland <Harry.Wentland@amd.com> Acked-by: Anthony Koo <Anthony.Koo@amd.com> Acked-by: Leo Li <sunpeng.li@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 923fe4951282cbdfce05186c10380bbc45b5e03b)
Kees Cook [Wed, 16 Jan 2019 18:31:09 +0000 (10:31 -0800)]
Yama: Check for pid death before checking ancestry
It's possible that a pid has died before we take the rcu lock, in which
case we can't walk the ancestry list as it may be detached. Instead, check
for death first before doing the walk.