media: videobuf2: Update vb2_is_busy() logic

Do not rely on the number of allocated buffers to know if the
queue is busy but on a flag set when at least one buffer has been allocated
by REQBUFS or CREATE_BUFS ioctl.
The flag is reset when REQBUFS is called with count = 0 or the file
handle is closed.
This is needed because remove buffers feature will be able to remove
all the buffers from a queue while streaming so relying on the number
of allocated buffers in the queue won't be possible.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

2 files changed, 7 insertions, 1 deletions

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index b6bf8f232f48..d8b3c04cb3b5 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -854,6 +854,7 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 		__vb2_queue_free(q, q_num_bufs);
 		mutex_unlock(&q->mmap_lock);
 
+		q->is_busy = 0;
 		/*
 		 * In case of REQBUFS(0) return immediately without calling
 		 * driver's queue_setup() callback and allocating resources.
@@ -966,6 +967,7 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 	 */
 	*count = allocated_buffers;
 	q->waiting_for_buffers = !q->is_output;
+	q->is_busy = 1;
 
 	return 0;
 
@@ -1091,6 +1093,7 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
 	 * to the userspace.
 	 */
 	*count = allocated_buffers;
+	q->is_busy = 1;
 
 	return 0;
 
@@ -2555,6 +2558,7 @@ void vb2_core_queue_release(struct vb2_queue *q)
 	__vb2_queue_free(q, vb2_get_num_buffers(q));
 	kfree(q->bufs);
 	q->bufs = NULL;
+	q->is_busy = 0;
 	mutex_unlock(&q->mmap_lock);
 }
 EXPORT_SYMBOL_GPL(vb2_core_queue_release);
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 8b86996b2719..667bf9ee1101 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -582,6 +582,7 @@ struct vb2_buf_ops {
  *		released. Used to prevent destroying the queue by other threads.
  * @is_multiplanar: set if buffer type is multiplanar
  * @is_output:	set if buffer type is output
+ * @is_busy:	set if at least one buffer has been allocated at some time.
  * @copy_timestamp: set if vb2-core should set timestamps
  * @last_buffer_dequeued: used in poll() and DQBUF to immediately return if the
  *		last decoded buffer was already dequeued. Set for capture queues
@@ -647,6 +648,7 @@ struct vb2_queue {
 	unsigned int			waiting_in_dqbuf:1;
 	unsigned int			is_multiplanar:1;
 	unsigned int			is_output:1;
+	unsigned int			is_busy:1;
 	unsigned int			copy_timestamp:1;
 	unsigned int			last_buffer_dequeued:1;
 
@@ -1166,7 +1168,7 @@ static inline unsigned int vb2_get_num_buffers(struct vb2_queue *q)
  */
 static inline bool vb2_is_busy(struct vb2_queue *q)
 {
-	return vb2_get_num_buffers(q) > 0;
+	return !!q->is_busy;
 }
 
 /**