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authorFlorian Echtler <floe@butterbrot.org>2015-03-31 06:43:28 -0300
committerMauro Carvalho Chehab <mchehab@osg.samsung.com>2015-04-08 06:28:56 -0300
commitc2529908a1905cd8b76bed0a6039975226cb24eb (patch)
treee6dba3f1a48f4d54cf060ee77f00a9e623dd6239 /drivers/input
parentaf7f388e7452e1707f862378f38a0372c6c33728 (diff)
[media] sur40: fix occasional hard freeze due to buffer queue underrun
This patch fixes a kernel panic which occurs when buf_list is empty. This can happen occasionally when user space is under heavy load (e.g. due to image processing on the CPU) and new buffers aren't re-queued fast enough. In that case, vb2_start_streaming_called can return true, but when the spinlock is taken and sur40_poll attempts to fetch the next buffer from buf_list, the list is in fact empty. This patch needs to be applied on top of the queued one adding V4L2 support to the sur40 driver. Signed-off-by: Florian Echtler <floe@butterbrot.org> Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Diffstat (limited to 'drivers/input')
-rw-r--r--drivers/input/touchscreen/sur40.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/input/touchscreen/sur40.c b/drivers/input/touchscreen/sur40.c
index b295e1744ea1..a24eba5ea843 100644
--- a/drivers/input/touchscreen/sur40.c
+++ b/drivers/input/touchscreen/sur40.c
@@ -380,6 +380,11 @@ static void sur40_process_video(struct sur40_state *sur40)
/* get a new buffer from the list */
spin_lock(&sur40->qlock);
+ if (list_empty(&sur40->buf_list)) {
+ dev_dbg(sur40->dev, "buffer queue empty\n");
+ spin_unlock(&sur40->qlock);
+ return;
+ }
new_buf = list_entry(sur40->buf_list.next, struct sur40_buffer, list);
list_del(&new_buf->list);
spin_unlock(&sur40->qlock);