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drm/msm/rd: Fix FIFO-full deadlock

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[ 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@chromium.org>
Patchwork: https://patchwork.freedesktop.org/patch/496706/
Link: https://lore.kernel.org/r/20220807160901.2353471-2-robdclark@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Rob Clark 2022-08-07 09:09:01 -07:00 committed by Greg Kroah-Hartman
parent 7e17397001
commit 7e214f5b2f
1 changed files with 3 additions and 0 deletions
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3
drivers/gpu/drm/msm/msm_rd.c
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@ -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.
*/