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locking/rtmutex: rcu: Add WRITE_ONCE() to rt_mutex ->owner 

The rt_mutex structure's ->owner field is read locklessly, so this
commit adds the WRITE_ONCE() to an update in order to provide proper
documentation and READ_ONCE()/WRITE_ONCE() pairing.

This data race was reported by KCSAN.  Not appropriate for backporting
due to failure being unlikely.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>
This commit is contained in:
Paul E. McKenney 2020-01-03 15:59:12 -08:00
parent 105abf82b0
commit 0050c7b2d2
1 changed files with 1 additions and 1 deletions
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2
kernel/locking/rtmutex.c
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@ -57,7 +57,7 @@ rt_mutex_set_owner(struct rt_mutex *lock, struct task_struct *owner)
if (rt_mutex_has_waiters(lock))
val |= RT_MUTEX_HAS_WAITERS;
lock->owner = (struct task_struct *)val;
WRITE_ONCE(lock->owner, (struct task_struct *)val);
}
static inline void clear_rt_mutex_waiters(struct rt_mutex *lock)