media: videobuf2: Use vb2_get_num_buffers() helper

Stop using queue num_buffers field directly, instead use
vb2_get_num_buffers().
This prepares for the future 'delete buffers' feature where there are
holes in the buffer indices.

Signed-off-by: Benjamin Gaignard <[e-mail]>
Signed-off-by: Hans Verkuil <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/common/videobuf2/videobuf2-core.c

···
 			     unsigned int num_buffers, unsigned int num_planes,
 			     const unsigned plane_sizes[VB2_MAX_PLANES])
 {
+	unsigned int q_num_buffers = vb2_get_num_buffers(q);
 	unsigned int buffer, plane;
 	struct vb2_buffer *vb;
 	int ret;
 
 	/* Ensure that q->num_buffers+num_buffers is below VB2_MAX_FRAME */
 	num_buffers = min_t(unsigned int, num_buffers,
-			    VB2_MAX_FRAME - q->num_buffers);
+			    VB2_MAX_FRAME - q_num_buffers);
 
 	for (buffer = 0; buffer < num_buffers; ++buffer) {
 		/* Allocate vb2 buffer structures */
···
 			vb->planes[plane].min_length = plane_sizes[plane];
 		}
 
-		vb2_queue_add_buffer(q, vb, q->num_buffers + buffer);
+		vb2_queue_add_buffer(q, vb, q_num_buffers + buffer);
 		call_void_bufop(q, init_buffer, vb);
 
 		/* Allocate video buffer memory for the MMAP type */
···
 {
 	unsigned int buffer;
 	struct vb2_buffer *vb;
+	unsigned int q_num_buffers = vb2_get_num_buffers(q);
 
-	for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
+	for (buffer = q_num_buffers - buffers; buffer < q_num_buffers;
 	     ++buffer) {
 		vb = vb2_get_buffer(q, buffer);
 		if (!vb)
···
 static void __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
 {
 	unsigned int buffer;
+	unsigned int q_num_buffers = vb2_get_num_buffers(q);
 
 	lockdep_assert_held(&q->mmap_lock);
 
 	/* Call driver-provided cleanup function for each buffer, if provided */
-	for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
+	for (buffer = q_num_buffers - buffers; buffer < q_num_buffers;
 	     ++buffer) {
 		struct vb2_buffer *vb = vb2_get_buffer(q, buffer);
 
···
 	 * Check that all the calls were balanced during the life-time of this
 	 * queue. If not then dump the counters to the kernel log.
 	 */
-	if (q->num_buffers) {
+	if (q_num_buffers) {
 		bool unbalanced = q->cnt_start_streaming != q->cnt_stop_streaming ||
 				  q->cnt_prepare_streaming != q->cnt_unprepare_streaming ||
 				  q->cnt_wait_prepare != q->cnt_wait_finish;
···
 		q->cnt_stop_streaming = 0;
 		q->cnt_unprepare_streaming = 0;
 	}
-	for (buffer = 0; buffer < q->num_buffers; ++buffer) {
+	for (buffer = 0; buffer < vb2_get_num_buffers(q); buffer++) {
 		struct vb2_buffer *vb = vb2_get_buffer(q, buffer);
 		bool unbalanced;
 
···
 #endif
 
 	/* Free vb2 buffers */
-	for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
+	for (buffer = q_num_buffers - buffers; buffer < q_num_buffers;
 	     ++buffer) {
 		struct vb2_buffer *vb = vb2_get_buffer(q, buffer);
 
···
 	}
 
 	q->num_buffers -= buffers;
-	if (!q->num_buffers) {
+	if (!vb2_get_num_buffers(q)) {
 		q->memory = VB2_MEMORY_UNKNOWN;
 		INIT_LIST_HEAD(&q->queued_list);
 	}
···
 static bool __buffers_in_use(struct vb2_queue *q)
 {
 	unsigned int buffer;
-	for (buffer = 0; buffer < q->num_buffers; ++buffer) {
+	for (buffer = 0; buffer < vb2_get_num_buffers(q); ++buffer) {
 		struct vb2_buffer *vb = vb2_get_buffer(q, buffer);
 
 		if (!vb)
···
 		     unsigned int flags, unsigned int *count)
 {
 	unsigned int num_buffers, allocated_buffers, num_planes = 0;
+	unsigned int q_num_bufs = vb2_get_num_buffers(q);
 	unsigned plane_sizes[VB2_MAX_PLANES] = { };
 	bool non_coherent_mem = flags & V4L2_MEMORY_FLAG_NON_COHERENT;
 	unsigned int i;
···
 		return -EBUSY;
 	}
 
-	if (*count == 0 || q->num_buffers != 0 ||
+	if (*count == 0 || q_num_bufs != 0 ||
 	    (q->memory != VB2_MEMORY_UNKNOWN && q->memory != memory) ||
 	    !verify_coherency_flags(q, non_coherent_mem)) {
 		/*
···
 		 * queued without ever calling STREAMON.
 		 */
 		__vb2_queue_cancel(q);
-		__vb2_queue_free(q, q->num_buffers);
+		__vb2_queue_free(q, q_num_bufs);
 		mutex_unlock(&q->mmap_lock);
 
 		/*
···
 	if (ret < 0) {
 		/*
 		 * Note: __vb2_queue_free() will subtract 'allocated_buffers'
-		 * from q->num_buffers and it will reset q->memory to
+		 * from already queued buffers and it will reset q->memory to
 		 * VB2_MEMORY_UNKNOWN.
 		 */
 		__vb2_queue_free(q, allocated_buffers);
···
 	unsigned int num_planes = 0, num_buffers, allocated_buffers;
 	unsigned plane_sizes[VB2_MAX_PLANES] = { };
 	bool non_coherent_mem = flags & V4L2_MEMORY_FLAG_NON_COHERENT;
-	bool no_previous_buffers = !q->num_buffers;
-	int ret;
+	unsigned int q_num_bufs = vb2_get_num_buffers(q);
+	bool no_previous_buffers = !q_num_bufs;
+	int ret = 0;
 
-	if (q->num_buffers == VB2_MAX_FRAME) {
+	if (q_num_bufs == VB2_MAX_FRAME) {
 		dprintk(q, 1, "maximum number of buffers already allocated\n");
 		return -ENOBUFS;
 	}
···
 			return -EINVAL;
 	}
 
-	num_buffers = min(*count, VB2_MAX_FRAME - q->num_buffers);
+	num_buffers = min(*count, VB2_MAX_FRAME - q_num_bufs);
 
 	if (requested_planes && requested_sizes) {
 		num_planes = requested_planes;
···
 		num_buffers = allocated_buffers;
 
 		/*
-		 * q->num_buffers contains the total number of buffers, that the
+		 * num_buffers contains the total number of buffers, that the
 		 * queue driver has set up
 		 */
 		ret = call_qop(q, queue_setup, q, &num_buffers,
···
 	if (ret < 0) {
 		/*
 		 * Note: __vb2_queue_free() will subtract 'allocated_buffers'
-		 * from q->num_buffers and it will reset q->memory to
+		 * from already queued buffers and it will reset q->memory to
 		 * VB2_MEMORY_UNKNOWN.
 		 */
 		__vb2_queue_free(q, allocated_buffers);
···
 		 * Forcefully reclaim buffers if the driver did not
 		 * correctly return them to vb2.
 		 */
-		for (i = 0; i < q->num_buffers; ++i) {
+		for (i = 0; i < vb2_get_num_buffers(q); ++i) {
 			vb = vb2_get_buffer(q, i);
 
 			if (!vb)
···
 	 * to vb2 in stop_streaming().
 	 */
 	if (WARN_ON(atomic_read(&q->owned_by_drv_count))) {
-		for (i = 0; i < q->num_buffers; ++i) {
+		for (i = 0; i < vb2_get_num_buffers(q); i++) {
 			struct vb2_buffer *vb = vb2_get_buffer(q, i);
 
 			if (!vb)
···
 	 * call to __fill_user_buffer() after buf_finish(). That order can't
 	 * be changed, so we can't move the buf_finish() to __vb2_dqbuf().
 	 */
-	for (i = 0; i < q->num_buffers; ++i) {
+	for (i = 0; i < vb2_get_num_buffers(q); i++) {
 		struct vb2_buffer *vb;
 		struct media_request *req;
 
···
 
 int vb2_core_streamon(struct vb2_queue *q, unsigned int type)
 {
+	unsigned int q_num_bufs = vb2_get_num_buffers(q);
 	int ret;
 
 	if (type != q->type) {
···
 		return 0;
 	}
 
-	if (!q->num_buffers) {
+	if (!q_num_bufs) {
 		dprintk(q, 1, "no buffers have been allocated\n");
 		return -EINVAL;
 	}
 
-	if (q->num_buffers < q->min_buffers_needed) {
+	if (q_num_bufs < q->min_buffers_needed) {
 		dprintk(q, 1, "need at least %u allocated buffers\n",
 				q->min_buffers_needed);
 		return -EINVAL;
···
 	__vb2_cleanup_fileio(q);
 	__vb2_queue_cancel(q);
 	mutex_lock(&q->mmap_lock);
-	__vb2_queue_free(q, q->num_buffers);
+	__vb2_queue_free(q, vb2_get_num_buffers(q));
 	mutex_unlock(&q->mmap_lock);
 }
 EXPORT_SYMBOL_GPL(vb2_core_queue_release);
···
 	/*
 	 * Start file I/O emulator only if streaming API has not been used yet.
 	 */
-	if (q->num_buffers == 0 && !vb2_fileio_is_active(q)) {
+	if (vb2_get_num_buffers(q) == 0 && !vb2_fileio_is_active(q)) {
 		if (!q->is_output && (q->io_modes & VB2_READ) &&
 				(req_events & (EPOLLIN | EPOLLRDNORM))) {
 			if (__vb2_init_fileio(q, 1))
···
 	 * For output streams you can call write() as long as there are fewer
 	 * buffers queued than there are buffers available.
 	 */
-	if (q->is_output && q->fileio && q->queued_count < q->num_buffers)
+	if (q->is_output && q->fileio && q->queued_count < vb2_get_num_buffers(q))
 		return EPOLLOUT | EPOLLWRNORM;
 
 	if (list_empty(&q->done_list)) {
···
  * struct vb2_fileio_data - queue context used by file io emulator
  *
  * @cur_index:	the index of the buffer currently being read from or
- *		written to. If equal to q->num_buffers then a new buffer
- *		must be dequeued.
+ *		written to. If equal to number of buffers in the vb2_queue
+ *		then a new buffer must be dequeued.
  * @initial_index: in the read() case all buffers are queued up immediately
  *		in __vb2_init_fileio() and __vb2_perform_fileio() just cycles
  *		buffers. However, in the write() case no buffers are initially
···
  *		buffers. This means that initially __vb2_perform_fileio()
  *		needs to know what buffer index to use when it is queuing up
  *		the buffers for the first time. That initial index is stored
- *		in this field. Once it is equal to q->num_buffers all
- *		available buffers have been queued and __vb2_perform_fileio()
- *		should start the normal dequeue/queue cycle.
+ *		in this field. Once it is equal to number of buffers in the
+ *		vb2_queue all available buffers have been queued and
+ *		__vb2_perform_fileio() should start the normal dequeue/queue cycle.
  *
  * vb2 provides a compatibility layer and emulator of file io (read and
  * write) calls on top of streaming API. For proper operation it required
···
 	/*
 	 * Check if streaming api has not been already activated.
 	 */
-	if (q->streaming || q->num_buffers > 0)
+	if (q->streaming || vb2_get_num_buffers(q) > 0)
 		return -EBUSY;
 
 	/*
···
 	/*
 	 * Get kernel address of each buffer.
 	 */
-	for (i = 0; i < q->num_buffers; i++) {
+	for (i = 0; i < vb2_get_num_buffers(q); i++) {
 		/* vb can never be NULL when using fileio. */
 		vb = vb2_get_buffer(q, i);
 
···
 		/*
 		 * Queue all buffers.
 		 */
-		for (i = 0; i < q->num_buffers; i++) {
+		for (i = 0; i < vb2_get_num_buffers(q); i++) {
 			struct vb2_buffer *vb2 = vb2_get_buffer(q, i);
 
 			if (!vb2)
···
 		}
 		/*
 		 * All buffers have been queued, so mark that by setting
-		 * initial_index to q->num_buffers
+		 * initial_index to the number of buffers in the vb2_queue
 		 */
-		fileio->initial_index = q->num_buffers;
-		fileio->cur_index = q->num_buffers;
+		fileio->initial_index = vb2_get_num_buffers(q);
+		fileio->cur_index = fileio->initial_index;
 	}
 
 	/*
···
 	 * Check if we need to dequeue the buffer.
 	 */
 	index = fileio->cur_index;
-	if (index >= q->num_buffers) {
+	if (index >= vb2_get_num_buffers(q)) {
 		struct vb2_buffer *b;
 
 		/*
···
 		 * If we are queuing up buffers for the first time, then
 		 * increase initial_index by one.
 		 */
-		if (fileio->initial_index < q->num_buffers)
+		if (fileio->initial_index < vb2_get_num_buffers(q))
 			fileio->initial_index++;
 		/*
 		 * The next buffer to use is either a buffer that's going to be
-		 * queued for the first time (initial_index < q->num_buffers)
-		 * or it is equal to q->num_buffers, meaning that the next
-		 * time we need to dequeue a buffer since we've now queued up
-		 * all the 'first time' buffers.
+		 * queued for the first time (initial_index < number of buffers in the vb2_queue)
+		 * or it is equal to the number of buffers in the vb2_queue,
+		 * meaning that the next time we need to dequeue a buffer since
+		 * we've now queued up all the 'first time' buffers.
 		 */
 		fileio->cur_index = fileio->initial_index;
 	}
···
 	int ret = 0;
 
 	if (q->is_output) {
-		prequeue = q->num_buffers;
+		prequeue = vb2_get_num_buffers(q);
 		copy_timestamp = q->copy_timestamp;
 	}
 

drivers/media/common/videobuf2/videobuf2-v4l2.c

···
 	 * This loop doesn't scale if there is a really large number of buffers.
 	 * Maybe something more efficient will be needed in this case.
 	 */
-	for (i = 0; i < q->num_buffers; i++) {
+	for (i = 0; i < vb2_get_num_buffers(q); i++) {
 		vb2 = vb2_get_buffer(q, i);
 
 		if (!vb2)
···
 
 	fill_buf_caps(q, &create->capabilities);
 	validate_memory_flags(q, create->memory, &create->flags);
-	create->index = q->num_buffers;
+	create->index = vb2_get_num_buffers(q);
 	if (create->count == 0)
 		return ret != -EBUSY ? ret : 0;