drm/msm: Unblock writer if reader closes file

BugLink: https://bugs.launchpad.net/bugs/1822271

[ Upstream commit 99c66bc0 ]

Prevents deadlock when fifo is full and reader closes file.
Signed-off-by: Kristian H. Kristensen <hoegsberg@chromium.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Juerg Haefliger <juerg.haefliger@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/gpu/drm/msm/msm_rd.c

@@ -103,7 +103,9 @@ 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;
 
 		n = min(sz, circ_space_to_end(&rd->fifo));
 		memcpy(fptr, ptr, n);
@@ -192,7 +194,10 @@ 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;
 }