This is a note to let you know that I've just added the patch titled
drm/msm/rd: Fix FIFO-full deadlock
to the 5.4-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-msm-rd-fix-fifo-full-deadlock.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit cf344c7952bd6906f37233151c47feed47f9c38a
Author: Rob Clark <robdclark@xxxxxxxxxxxx>
Date: Sun Aug 7 09:09:01 2022 -0700
drm/msm/rd: Fix FIFO-full deadlock
[ Upstream commit 174974d8463b77c2b4065e98513adb204e64de7d ]
If the previous thing cat'ing $debugfs/rd left the FIFO full, then
subsequent open could deadlock in rd_write() (because open is blocked,
not giving a chance for read() to consume any data in the FIFO). Also
it is generally a good idea to clear out old data from the FIFO.
Signed-off-by: Rob Clark <robdclark@xxxxxxxxxxxx>
Patchwork: https://patchwork.freedesktop.org/patch/496706/
Link: https://lore.kernel.org/r/20220807160901.2353471-2-robdclark@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/msm/msm_rd.c b/drivers/gpu/drm/msm/msm_rd.c
index c7832a951039f..a6b024b06b363 100644
--- a/drivers/gpu/drm/msm/msm_rd.c
+++ b/drivers/gpu/drm/msm/msm_rd.c
@@ -191,6 +191,9 @@ static int rd_open(struct inode *inode, struct file *file)
file->private_data = rd;
rd->open = true;
+ /* Reset fifo to clear any previously unread data: */
+ rd->fifo.head = rd->fifo.tail = 0;
+
/* the parsing tools need to know gpu-id to know which
* register database to load.
*/
