This is a note to let you know that I've just added the patch titled
drm/vkms: fix misuse of WARN_ON
to the 5.10-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-vkms-fix-misuse-of-warn_on.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b531306ade93d10ab5663a2e255f18c2ebc9a06d
Author: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Date: Sat Mar 20 14:28:40 2021 +0100
drm/vkms: fix misuse of WARN_ON
[ Upstream commit b4142fc4d52d051d4d8df1fb6c569e5b445d369e ]
vkms_vblank_simulate() uses WARN_ON for timing-dependent condition
(timer overrun). This is a mis-use of WARN_ON, WARN_ON must be used
to denote kernel bugs. Use pr_warn() instead.
Signed-off-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Reported-by: syzbot+4fc21a003c8332eb0bdd@xxxxxxxxxxxxxxxxxxxxxxxxx
Cc: Rodrigo Siqueira <rodrigosiqueiramelo@xxxxxxxxx>
Cc: Melissa Wen <melissa.srw@xxxxxxxxx>
Cc: Haneen Mohammed <hamohammed.sa@xxxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
Cc: David Airlie <airlied@xxxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Acked-by: Melissa Wen <melissa.srw@xxxxxxxxx>
Signed-off-by: Melissa Wen <melissa.srw@xxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20210320132840.1315853-1-dvyukov@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
index 09c012d54d58..1ae5cd47d954 100644
--- a/drivers/gpu/drm/vkms/vkms_crtc.c
+++ b/drivers/gpu/drm/vkms/vkms_crtc.c
@@ -18,7 +18,8 @@ static enum hrtimer_restart vkms_vblank_simulate(struct hrtimer *timer)
ret_overrun = hrtimer_forward_now(&output->vblank_hrtimer,
output->period_ns);
- WARN_ON(ret_overrun != 1);
+ if (ret_overrun != 1)
+ pr_warn("%s: vblank timer overrun\n", __func__);
spin_lock(&output->lock);
ret = drm_crtc_handle_vblank(crtc);
