From ce16889c87c2e9b5eb4d79a7072190e4ca7364d0 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Fri, 4 Aug 2017 09:23:28 +0100 Subject: drm: Wake up next in drm_read() chain if we are forced to putback the event MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit [ Upstream commit 60b801999c48b6c1dd04e653a38e2e613664264e ] After an event is sent, we try to copy it into the user buffer of the first waiter in drm_read() and if the user buffer doesn't have enough room we put it back onto the list. However, we didn't wake up any subsequent waiter, so that event may sit on the list until either a new vblank event is sent or a new waiter appears. Rare, but in the worst case may lead to a stuck process. Testcase: igt/drm_read/short-buffer-wakeup Signed-off-by: Chris Wilson Cc: Daniel Vetter Reviewed-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20170804082328.17173-1-chris@chris-wilson.co.uk Signed-off-by: Sasha Levin --- drivers/gpu/drm/drm_file.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/gpu/drm/drm_file.c b/drivers/gpu/drm/drm_file.c index 03244b3c985d..3cf07f5063ff 100644 --- a/drivers/gpu/drm/drm_file.c +++ b/drivers/gpu/drm/drm_file.c @@ -525,6 +525,7 @@ put_back_event: file_priv->event_space -= length; list_add(&e->link, &file_priv->event_list); spin_unlock_irq(&dev->event_lock); + wake_up_interruptible(&file_priv->event_wait); break; } -- cgit v1.2.3