This is a note to let you know that I've just added the patch titled
drm/xe/ufence: Wake up waiters after setting ufence->signalled
to the 6.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-xe-ufence-wake-up-waiters-after-setting-ufence-s.patch
and it can be found in the queue-6.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 6680a77f34d2b742bd28c5d1eb4299fa84aba1d1
Author: Nirmoy Das <nirmoy.das@xxxxxxxxx>
Date: Thu Nov 14 16:05:37 2024 +0100
drm/xe/ufence: Wake up waiters after setting ufence->signalled
[ Upstream commit 37a1cf288e4538eb39b38dbc745fe0da7ae53d94 ]
If a previous ufence is not signalled, vm_bind will return -EBUSY.
Delaying the modification of ufence->signalled can cause issues if the
UMD reuses the same ufence so update ufence->signalled before waking up
waiters.
Cc: Matthew Brost <matthew.brost@xxxxxxxxx>
Link: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/3233
Fixes: 977e5b82e090 ("drm/xe: Expose user fence from xe_sync_entry")
Reviewed-by: Matthew Brost <matthew.brost@xxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20241114150537.4161573-1-nirmoy.das@xxxxxxxxx
Signed-off-by: Nirmoy Das <nirmoy.das@xxxxxxxxx>
(cherry picked from commit 553a5d14fcd927194c409b10faced6a6dbc678d1)
Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/xe/xe_sync.c b/drivers/gpu/drm/xe/xe_sync.c
index 9d77f2d4096f5..6e17bace67dd1 100644
--- a/drivers/gpu/drm/xe/xe_sync.c
+++ b/drivers/gpu/drm/xe/xe_sync.c
@@ -85,8 +85,12 @@ static void user_fence_worker(struct work_struct *w)
mmput(ufence->mm);
}
- wake_up_all(&ufence->xe->ufence_wq);
+ /*
+ * Wake up waiters only after updating the ufence state, allowing the UMD
+ * to safely reuse the same ufence without encountering -EBUSY errors.
+ */
WRITE_ONCE(ufence->signalled, 1);
+ wake_up_all(&ufence->xe->ufence_wq);
user_fence_put(ufence);
}
