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@xxxxxxxxxxxxxx>
---
drivers/input/touchscreen/sur40.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/input/touchscreen/sur40.c b/drivers/input/touchscreen/sur40.c
index 1e7dacf..d618514 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);
--
1.9.1
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