diff options
| author | Andrea Parri <andrea.parri@amarulasolutions.com> | 2019-01-21 16:52:40 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-04-05 22:33:12 +0200 |
| commit | e8e0bd4915ec8b2ee7b69f966719329ec65ba781 (patch) | |
| tree | 3b47d539c99fb55f5691e8f0be412e358ba7085e /include/linux | |
| parent | b12a060a0bd217ca75e96ad5c06bae962d8d7030 (diff) | |
| download | linux-stable-e8e0bd4915ec8b2ee7b69f966719329ec65ba781.tar.gz linux-stable-e8e0bd4915ec8b2ee7b69f966719329ec65ba781.tar.bz2 linux-stable-e8e0bd4915ec8b2ee7b69f966719329ec65ba781.zip | |
sched/core: Use READ_ONCE()/WRITE_ONCE() in move_queued_task()/task_rq_lock()
[ Upstream commit c546951d9c9300065bad253ecdf1ac59ce9d06c8 ]
move_queued_task() synchronizes with task_rq_lock() as follows:
move_queued_task() task_rq_lock()
[S] ->on_rq = MIGRATING [L] rq = task_rq()
WMB (__set_task_cpu()) ACQUIRE (rq->lock);
[S] ->cpu = new_cpu [L] ->on_rq
where "[L] rq = task_rq()" is ordered before "ACQUIRE (rq->lock)" by an
address dependency and, in turn, "ACQUIRE (rq->lock)" is ordered before
"[L] ->on_rq" by the ACQUIRE itself.
Use READ_ONCE() to load ->cpu in task_rq() (c.f., task_cpu()) to honor
this address dependency. Also, mark the accesses to ->cpu and ->on_rq
with READ_ONCE()/WRITE_ONCE() to comply with the LKMM.
Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul E. McKenney <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Link: https://lkml.kernel.org/r/20190121155240.27173-1-andrea.parri@amarulasolutions.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/sched.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 4abb5bd74b04..5dc024e28397 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1737,9 +1737,9 @@ static __always_inline bool need_resched(void) static inline unsigned int task_cpu(const struct task_struct *p) { #ifdef CONFIG_THREAD_INFO_IN_TASK - return p->cpu; + return READ_ONCE(p->cpu); #else - return task_thread_info(p)->cpu; + return READ_ONCE(task_thread_info(p)->cpu); #endif } |