From 9b61db1aed5c62180a374ab4dd774d1625bdd8d4 Mon Sep 17 00:00:00 2001 From: Hans de Goede Date: Sun, 11 Aug 2019 16:37:24 +0200 Subject: [PATCH] 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 Signed-off-by: Hans de Goede Link: https://patchwork.freedesktop.org/patch/msgid/20190811143725.5951-1-hdegoede@redhat.com --- drivers/gpu/drm/tiny/gm12u320.c | 14 ++------------ 1 file 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; -- 2.11.0