V4L/DVB: videobuf: prepare to make locking optional in videobuf

Currently videobuf uses the vb_lock mutex to lock its data structures.
But this locking will (optionally) move into the v4l2 core, which means
that in that case vb_lock shouldn't be used since the external lock is already
held.

Prepare for this by adding a pointer to such an external mutex and
don't lock if that pointer is set.

Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/include/media/videobuf-core.h b/include/media/videobuf-core.h
index f2c41cebf453..f5eb2cbf3002 100644
--- a/include/media/videobuf-core.h
+++ b/include/media/videobuf-core.h
@@ -139,6 +139,7 @@ struct videobuf_qtype_ops {
 
 struct videobuf_queue {
 	struct mutex               vb_lock;
+	struct mutex               *ext_lock;
 	spinlock_t                 *irqlock;
 	struct device		   *dev;
 
@@ -167,6 +168,18 @@ struct videobuf_queue {
 	void                       *priv_data;
 };
 
+static inline void videobuf_queue_lock(struct videobuf_queue *q)
+{
+	if (!q->ext_lock)
+		mutex_lock(&q->vb_lock);
+}
+
+static inline void videobuf_queue_unlock(struct videobuf_queue *q)
+{
+	if (!q->ext_lock)
+		mutex_unlock(&q->vb_lock);
+}
+
 int videobuf_waiton(struct videobuf_buffer *vb, int non_blocking, int intr);
 int videobuf_iolock(struct videobuf_queue *q, struct videobuf_buffer *vb,
 		struct v4l2_framebuffer *fbuf);