futex: Use smp_store_release() in mark_wake_futex()
Since the futex_q can dissapear the instruction after assigning NULL, this really should be a RELEASE barrier. That stops loads from hitting dead memory too. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: juri.lelli@arm.com Cc: bigeasy@linutronix.de Cc: xlpang@redhat.com Cc: rostedt@goodmis.org Cc: mathieu.desnoyers@efficios.com Cc: jdesfossez@efficios.com Cc: dvhart@infradead.org Cc: bristot@redhat.com Link: http://lkml.kernel.org/r/20170322104151.604296452@infradead.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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@ -1290,8 +1290,7 @@ static void mark_wake_futex(struct wake_q_head *wake_q, struct futex_q *q)
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* memory barrier is required here to prevent the following
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* memory barrier is required here to prevent the following
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* store to lock_ptr from getting ahead of the plist_del.
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* store to lock_ptr from getting ahead of the plist_del.
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*/
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*/
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smp_wmb();
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smp_store_release(&q->lock_ptr, NULL);
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q->lock_ptr = NULL;
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}
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}
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static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *top_waiter,
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static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_q *top_waiter,
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