linux-kernel - [PATCH 4.14 07/52] drm/msm: Unblock writer if reader closes file

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Date:   Mon,  4 Mar 2019 09:22:05 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Kristian H. Kristensen" <hoegsberg@...omium.org>,
        Rob Clark <robdclark@...il.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.14 07/52] drm/msm: Unblock writer if reader closes file

4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

[ Upstream commit 99c66bc051e7407fe0bf0607b142ec0be1a1d1dd ]

Prevents deadlock when fifo is full and reader closes file.

Signed-off-by: Kristian H. Kristensen <hoegsberg@...omium.org>
Signed-off-by: Rob Clark <robdclark@...il.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/msm/msm_rd.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/msm/msm_rd.c b/drivers/gpu/drm/msm/msm_rd.c
index ec56794ad0399..bdce1c9434c6c 100644
--- a/drivers/gpu/drm/msm/msm_rd.c
+++ b/drivers/gpu/drm/msm/msm_rd.c
@@ -109,7 +109,9 @@ static void rd_write(struct msm_rd_state *rd, const void *buf, int sz)
 		char *fptr = &fifo->buf[fifo->head];
 		int n;
 
-		wait_event(rd->fifo_event, circ_space(&rd->fifo) > 0);
+		wait_event(rd->fifo_event, circ_space(&rd->fifo) > 0 || !rd->open);
+		if (!rd->open)
+			return;
 
 		/* Note that smp_load_acquire() is not strictly required
 		 * as CIRC_SPACE_TO_END() does not access the tail more
@@ -207,7 +209,10 @@ static int rd_open(struct inode *inode, struct file *file)
 static int rd_release(struct inode *inode, struct file *file)
 {
 	struct msm_rd_state *rd = inode->i_private;
+
 	rd->open = false;
+	wake_up_all(&rd->fifo_event);
+
 	return 0;
 }
 
-- 
2.19.1