From eaeb5d2f0a3fe042824f1db21938eef28ef38f72 Mon Sep 17 00:00:00 2001 From: Rob Clark Date: Sun, 7 Aug 2022 09:09:01 -0700 Subject: [PATCH] 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 Patchwork: https://patchwork.freedesktop.org/patch/496706/ Link: https://lore.kernel.org/r/20220807160901.2353471-2-robdclark@gmail.com Signed-off-by: Sasha Levin --- 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 bdce1c9434c6..54891cbf4f50 100644 --- a/drivers/gpu/drm/msm/msm_rd.c +++ b/drivers/gpu/drm/msm/msm_rd.c @@ -193,6 +193,9 @@ 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. */ -- 2.20.1