This is a note to let you know that I've just added the patch titled
drm/radeon: Fix error handling in radeon_flip_work_func.
to the 4.4-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-radeon-fix-error-handling-in-radeon_flip_work_func.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1e1490a38504419e349caa1b7d55d5c141a9bccb Mon Sep 17 00:00:00 2001
From: Mario Kleiner <mario.kleiner.de@xxxxxxxxx>
Date: Tue, 1 Mar 2016 21:31:17 +0100
Subject: drm/radeon: Fix error handling in radeon_flip_work_func.
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From: Mario Kleiner <mario.kleiner.de@xxxxxxxxx>
commit 1e1490a38504419e349caa1b7d55d5c141a9bccb upstream.
This is a port of the patch "drm/amdgpu: Fix error handling in amdgpu_flip_work_func."
to fix the following problem for radeon as well which was
reported against amdgpu:
The patch e1d09dc0ccc6: "drm/amdgpu: Don't hang in
amdgpu_flip_work_func on disabled crtc." from Feb 19, 2016, leads to
the following static checker warning, as reported by Dan Carpenter in
https://lists.freedesktop.org/archives/dri-devel/2016-February/101987.html
drivers/gpu/drm/amd/amdgpu/amdgpu_display.c:127 amdgpu_flip_work_func() warn: should this be 'repcnt == -1'
drivers/gpu/drm/amd/amdgpu/amdgpu_display.c:136 amdgpu_flip_work_func() error: double unlock 'spin_lock:&crtc->dev->event_lock'
drivers/gpu/drm/amd/amdgpu/amdgpu_display.c:136 amdgpu_flip_work_func() error: double unlock 'irqsave:flags'
This patch fixes both reported problems:
Change post-decrement of repcnt to pre-decrement, so
it can't underflow anymore, but still performs up to
three repetitions - three is the maximum one could
expect in practice.
Move the spin_unlock_irqrestore to where it actually
belongs.
Reviewed-by: Michel Dänzer <michel.daenzer@xxxxxxx>
Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Signed-off-by: Mario Kleiner <mario.kleiner.de@xxxxxxxxx>
Cc: Michel Dänzer <michel.daenzer@xxxxxxx>
Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/radeon/radeon_display.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -455,7 +455,7 @@ static void radeon_flip_work_func(struct
* In practice this won't execute very often unless on very fast
* machines because the time window for this to happen is very small.
*/
- while (radeon_crtc->enabled && repcnt--) {
+ while (radeon_crtc->enabled && --repcnt) {
/* GET_DISTANCE_TO_VBLANKSTART returns distance to real vblank
* start in hpos, and to the "fudged earlier" vblank start in
* vpos.
@@ -471,13 +471,13 @@ static void radeon_flip_work_func(struct
break;
/* Sleep at least until estimated real start of hw vblank */
- spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
min_udelay = (-hpos + 1) * max(vblank->linedur_ns / 1000, 5);
if (min_udelay > vblank->framedur_ns / 2000) {
/* Don't wait ridiculously long - something is wrong */
repcnt = 0;
break;
}
+ spin_unlock_irqrestore(&crtc->dev->event_lock, flags);
usleep_range(min_udelay, 2 * min_udelay);
spin_lock_irqsave(&crtc->dev->event_lock, flags);
};
Patches currently in stable-queue which might be from mario.kleiner.de@xxxxxxxxx are
queue-4.4/drm-amdgpu-fix-error-handling-in-amdgpu_flip_work_func.patch
queue-4.4/drm-radeon-fix-error-handling-in-radeon_flip_work_func.patch
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