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authorChris Wilson <chris@chris-wilson.co.uk>2017-08-04 09:23:28 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2019-05-31 06:48:31 -0700
commite658aba58f03a040586e5e12ad6ca20f3b1694e6 (patch)
tree16111c6132e392db6d9e8e6f2b8b1078a83774d4
parent00cefe3441d5f97657f2a3b86fe1368ea9a4bfcd (diff)
drm: Wake up next in drm_read() chain if we are forced to putback the event
[ 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 <chris@chris-wilson.co.uk> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20170804082328.17173-1-chris@chris-wilson.co.uk Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r--drivers/gpu/drm/drm_fops.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_fops.c b/drivers/gpu/drm/drm_fops.c
index c37b7b5f1dd3..921f7f690ae9 100644
--- a/drivers/gpu/drm/drm_fops.c
+++ b/drivers/gpu/drm/drm_fops.c
@@ -515,6 +515,7 @@ 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;
}