From: Rob Clark <robdclark@xxxxxxxxxxxx> [ 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> --- drivers/gpu/drm/msm/msm_rd.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/gpu/drm/msm/msm_rd.c b/drivers/gpu/drm/msm/msm_rd.c index a92ffde53f0b3..db2f847c8535f 100644 --- a/drivers/gpu/drm/msm/msm_rd.c +++ b/drivers/gpu/drm/msm/msm_rd.c @@ -196,6 +196,9 @@ 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. * -- 2.35.1
