From: Ben Hutchings <ben@decadent.org.uk>
To: stable@vger.kernel.org
Cc: Lee Jones <lee.jones@linaro.org>,
"Luis Claudio R. Goncalves" <lgoncalv@redhat.com>,
Florian Fainelli <f.fainelli@gmail.com>
Subject: [PATCH 01/13] futex: Use smp_store_release() in mark_wake_futex()
Date: Sun, 28 Mar 2021 22:40:54 +0200 [thread overview]
Message-ID: <YGDp1qJOCUJmE1Ty@decadent.org.uk> (raw)
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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);
}
/*
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next reply other threads:[~2021-03-28 20:41 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-28 20:40 Ben Hutchings [this message]
2021-03-28 20:41 ` [PATCH 02/13] futex,rt_mutex: Introduce rt_mutex_init_waiter() Ben Hutchings
2021-03-28 20:41 ` [PATCH 03/13] futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock() Ben Hutchings
2021-03-28 20:41 ` [PATCH 04/13] futex: Drop hb->lock before enqueueing on the rtmutex Ben Hutchings
2021-03-28 20:42 ` [PATCH 05/13] futex: Avoid freeing an active timer Ben Hutchings
2021-03-28 20:42 ` [PATCH 06/13] futex,rt_mutex: Fix rt_mutex_cleanup_proxy_lock() Ben Hutchings
2021-03-28 20:42 ` [PATCH 07/13] futex: Handle early deadlock return correctly Ben Hutchings
2021-03-28 20:42 ` [PATCH 08/13] futex: Fix (possible) missed wakeup Ben Hutchings
2021-03-28 20:42 ` [PATCH 09/13] locking/futex: Allow low-level atomic operations to return -EAGAIN Ben Hutchings
2021-03-28 20:42 ` [PATCH 10/13] arm64: futex: Bound number of LDXR/STXR loops in FUTEX_WAKE_OP Ben Hutchings
2021-03-28 20:42 ` [PATCH 11/13] futex: Prevent robust futex exit race Ben Hutchings
2021-03-28 20:43 ` [PATCH 12/13] futex: Fix incorrect should_fail_futex() handling Ben Hutchings
2021-03-28 20:43 ` [PATCH 13/13] futex: Handle transient "ownerless" rtmutex state correctly Ben Hutchings
2021-03-29 5:50 ` [PATCH 01/13] futex: Use smp_store_release() in mark_wake_futex() Greg KH
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