[PATCH AUTOSEL 5.4 26/57] drm/vkms: fix misuse of WARN_ON

Sasha Levin
2021-05-03T16:52:53Z

From: Dmitry Vyukov <dvyukov@google.com>

[ 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@google.com>
Reported-by: syzbot+4fc21a003c8332eb0bdd@syzkaller.appspotmail.com
Cc: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Cc: Melissa Wen <melissa.srw@gmail.com>
Cc: Haneen Mohammed <hamohammed.sa@gmail.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: David Airlie <airlied@linux.ie>
Cc: dri-devel@lists.freedesktop.org
Cc: linux-kernel@vger.kernel.org
Acked-by: Melissa Wen <melissa.srw@gmail.com>
Signed-off-by: Melissa Wen <melissa.srw@gmail.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210320132840.1315853-1-dvyukov@google.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/vkms/vkms_crtc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vkms/vkms_crtc.c b/drivers/gpu/drm/vkms/vkms_crtc.c
index 927dafaebc76..8b01fae65f43 100644
--- a/drivers/gpu/drm/vkms/vkms_crtc.c
+++ b/drivers/gpu/drm/vkms/vkms_crtc.c
@@ -20,7 +20,8 @@ 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__);

ret = drm_crtc_handle_vblank(crtc);
if (!ret)
--
2.30.2