| Message ID | YGDp1qJOCUJmE1Ty@decadent.org.uk |
|---|---|
| State | New |
| Headers | show |
| Series | [01/13] futex: Use smp_store_release() in mark_wake_futex() | expand |
On Sun, Mar 28, 2021 at 10:40:54PM +0200, Ben Hutchings wrote: > From: Peter Zijlstra <peterz@infradead.org> > > commit 1b367ece0d7e696cab1c8501bab282cc6a538b3f upstream. > > 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> > Signed-off-by: Ben Hutchings <ben@decadent.org.uk> > --- > kernel/futex.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/kernel/futex.c b/kernel/futex.c > index 796b1c860839..e112a9d4c84f 100644 > --- a/kernel/futex.c > +++ b/kernel/futex.c > @@ -1565,8 +1565,7 @@ static void mark_wake_futex(struct wake_q_head *wake_q, struct futex_q *q) > * memory barrier is required here to prevent the following > * store to lock_ptr from getting ahead of the plist_del. > */ > - smp_wmb(); > - q->lock_ptr = NULL; > + smp_store_release(&q->lock_ptr, NULL); > } > > /* > All now queued up, thanks. greg k-h
diff --git a/kernel/futex.c b/kernel/futex.c index 796b1c860839..e112a9d4c84f 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -1565,8 +1565,7 @@ static void mark_wake_futex(struct wake_q_head *wake_q, struct futex_q *q) * memory barrier is required here to prevent the following * store to lock_ptr from getting ahead of the plist_del. */ - smp_wmb(); - q->lock_ptr = NULL; + smp_store_release(&q->lock_ptr, NULL); } /*