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| author | Hans de Goede <hdegoede@redhat.com> | 2019-08-11 16:37:24 +0200 |
|---|---|---|
| committer | Hans de Goede <hdegoede@redhat.com> | 2019-08-12 21:30:20 +0200 |
| commit | 9b61db1aed5c62180a374ab4dd774d1625bdd8d4 (patch) | |
| tree | ca8be2e79efbd0950489584c42d8547f97c93e63 /drivers/gpu/drm/tiny | |
| parent | 4abfa2e4e74f22fff67d561d01f8e080b5b547be (diff) | |
| download | linux-9b61db1aed5c62180a374ab4dd774d1625bdd8d4.tar.gz | |
drm: gm12u320: Do not take a mutex from a wait_event condition
I made the condition of the wait_event_timeout call in
gm12u320_fb_update_work a helper which takes a mutex to make sure
that any writes to fb_update.run or fb_update.fb from other CPU cores
are seen before the check is done.
This is not necessary as the wait_event helpers contain the necessary
barriers for this themselves.
More over it is harmfull since by the time the check is done the task
is no longer in the TASK_RUNNING state and calling mutex_lock while not
in task-running is not allowed, leading to this warning when the kernel
is build with some extra locking checks enabled:
[11947.450011] do not call blocking ops when !TASK_RUNNING; state=2 set at
[<00000000e4306de6>] prepare_to_wait_event+0x61/0x190
This commit fixes this by dropping the helper and simply directly
checking the condition (without unnecessary locking) in the
wait_event_timeout call.
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190811143725.5951-1-hdegoede@redhat.com
Diffstat (limited to 'drivers/gpu/drm/tiny')
| -rw-r--r-- | drivers/gpu/drm/tiny/gm12u320.c | 14 |
1 files changed, 2 insertions, 12 deletions
diff --git a/drivers/gpu/drm/tiny/gm12u320.c b/drivers/gpu/drm/tiny/gm12u320.c index 1fd6db52af92..aa4b46e47e19 100644 --- a/drivers/gpu/drm/tiny/gm12u320.c +++ b/drivers/gpu/drm/tiny/gm12u320.c @@ -342,17 +342,6 @@ unlock: mutex_unlock(&gm12u320->fb_update.lock); } -static int gm12u320_fb_update_ready(struct gm12u320_device *gm12u320) -{ - int ret; - - mutex_lock(&gm12u320->fb_update.lock); - ret = !gm12u320->fb_update.run || gm12u320->fb_update.fb != NULL; - mutex_unlock(&gm12u320->fb_update.lock); - - return ret; -} - static void gm12u320_fb_update_work(struct work_struct *work) { struct gm12u320_device *gm12u320 = @@ -426,7 +415,8 @@ static void gm12u320_fb_update_work(struct work_struct *work) * switches back to showing its logo. */ wait_event_timeout(gm12u320->fb_update.waitq, - gm12u320_fb_update_ready(gm12u320), + !gm12u320->fb_update.run || + gm12u320->fb_update.fb != NULL, IDLE_TIMEOUT); } return; |