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authorThomas Zimmermann <tzimmermann@suse.de>2024-02-07 13:01:19 +0100
committerThomas Zimmermann <tzimmermann@suse.de>2024-02-07 13:02:20 +0100
commit0e85f1ae4ac6dae238b0f35232d1aa52e1b6943f (patch)
tree75b387bc359637c15b90ababb1ff073ca68b5bd8 /kernel/futex/core.c
parent2c8ba564a42c7418a726367c73d7c88454848fdc (diff)
parentf8e4806e0dfa8796b3d7076a7fe054455a59c38b (diff)
Merge drm/drm-next into drm-misc-next
Backmerging to update drm-misc-next to the state of v6.8-rc3. Also fixes a build problem with xe. Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Diffstat (limited to 'kernel/futex/core.c')
-rw-r--r--kernel/futex/core.c15
1 files changed, 12 insertions, 3 deletions
diff --git a/kernel/futex/core.c b/kernel/futex/core.c
index e0e853412c15..1e78ef24321e 100644
--- a/kernel/futex/core.c
+++ b/kernel/futex/core.c
@@ -627,12 +627,21 @@ retry:
}
/*
- * PI futexes can not be requeued and must remove themselves from the
- * hash bucket. The hash bucket lock (i.e. lock_ptr) is held.
+ * PI futexes can not be requeued and must remove themselves from the hash
+ * bucket. The hash bucket lock (i.e. lock_ptr) is held.
*/
void futex_unqueue_pi(struct futex_q *q)
{
- __futex_unqueue(q);
+ /*
+ * If the lock was not acquired (due to timeout or signal) then the
+ * rt_waiter is removed before futex_q is. If this is observed by
+ * an unlocker after dropping the rtmutex wait lock and before
+ * acquiring the hash bucket lock, then the unlocker dequeues the
+ * futex_q from the hash bucket list to guarantee consistent state
+ * vs. userspace. Therefore the dequeue here must be conditional.
+ */
+ if (!plist_node_empty(&q->list))
+ __futex_unqueue(q);
BUG_ON(!q->pi_state);
put_pi_state(q->pi_state);