[PATCH v9 49/53] media: core: Add bitmap manage bufs array entries

[Benjamin Gaignard]

Add a bitmap field to know which of bufs array entries are
used or not.
Remove no more used num_buffers field from queue structure.
Use bitmap_find_next_zero_area() to find the first possible
range when creating new buffers to fill the gaps.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx>
---
 .../media/common/videobuf2/videobuf2-core.c   | 43 ++++++++++++++-----
 include/media/videobuf2-core.h                | 19 +++++---
 2 files changed, 47 insertions(+), 15 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 92de8af58bdc..4cbc17e8b53e 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -412,11 +412,12 @@ static void init_buffer_cache_hints(struct vb2_queue *q, struct vb2_buffer *vb)
  */
 static void vb2_queue_add_buffer(struct vb2_queue *q, struct vb2_buffer *vb, unsigned int index)
 {
-	WARN_ON(index >= q->max_num_buffers || q->bufs[index]);
+	WARN_ON(index >= q->max_num_buffers || test_bit(index, q->bufs_bitmap));
 
 	q->bufs[index] = vb;
 	vb->index = index;
 	vb->vb2_queue = q;
+	set_bit(index, q->bufs_bitmap);
 }
 
 /**
@@ -425,8 +426,7 @@ static void vb2_queue_add_buffer(struct vb2_queue *q, struct vb2_buffer *vb, uns
  */
 static void vb2_queue_remove_buffer(struct vb2_buffer *vb)
 {
-	if (vb->vb2_queue->num_buffers)
-		vb->vb2_queue->num_buffers--;
+	clear_bit(vb->index, vb->vb2_queue->bufs_bitmap);
 	vb->vb2_queue->bufs[vb->index] = NULL;
 	vb->vb2_queue = NULL;
 }
@@ -448,11 +448,12 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
 	unsigned long index;
 	int ret;
 
-	/* Ensure that the number of already queue + num_buffers is below q->max_num_buffers */
+	/* Ensure that vb2_get_num_buffers(q) + num_buffers is no more than q->max_num_buffers */
 	num_buffers = min_t(unsigned int, num_buffers,
 			    q->max_num_buffers - vb2_get_num_buffers(q));
 
-	index = vb2_get_num_buffers(q);
+	index = bitmap_find_next_zero_area(q->bufs_bitmap, q->max_num_buffers,
+					   0, num_buffers, 0);
 
 	*first_index = index;
 
@@ -874,6 +875,14 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 		q->bufs = kcalloc(q->max_num_buffers, sizeof(*q->bufs), GFP_KERNEL);
 	if (!q->bufs)
 		ret = -ENOMEM;
+
+	if (!q->bufs_bitmap)
+		q->bufs_bitmap = bitmap_zalloc(q->max_num_buffers, GFP_KERNEL);
+	if (!q->bufs_bitmap) {
+		ret = -ENOMEM;
+		kfree(q->bufs);
+		q->bufs = NULL;
+	}
 	q->memory = memory;
 	mutex_unlock(&q->mmap_lock);
 	if (ret)
@@ -943,7 +952,6 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 	}
 
 	mutex_lock(&q->mmap_lock);
-	q->num_buffers = allocated_buffers;
 
 	if (ret < 0) {
 		/*
@@ -970,6 +978,10 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
 	mutex_lock(&q->mmap_lock);
 	q->memory = VB2_MEMORY_UNKNOWN;
 	mutex_unlock(&q->mmap_lock);
+	kfree(q->bufs);
+	q->bufs = NULL;
+	bitmap_free(q->bufs_bitmap);
+	q->bufs_bitmap = NULL;
 	return ret;
 }
 EXPORT_SYMBOL_GPL(vb2_core_reqbufs);
@@ -1006,9 +1018,19 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
 		q->memory = memory;
 		if (!q->bufs)
 			q->bufs = kcalloc(q->max_num_buffers, sizeof(*q->bufs), GFP_KERNEL);
-		if (!q->bufs)
+		if (!q->bufs) {
 			ret = -ENOMEM;
+			goto unlock;
+		}
+		if (!q->bufs_bitmap)
+			q->bufs_bitmap = bitmap_zalloc(q->max_num_buffers, GFP_KERNEL);
+		if (!q->bufs_bitmap) {
+			ret = -ENOMEM;
+			kfree(q->bufs);
+			q->bufs = NULL;
+		}
 		mutex_unlock(&q->mmap_lock);
+unlock:
 		if (ret)
 			return ret;
 		q->waiting_for_buffers = !q->is_output;
@@ -1070,7 +1092,6 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
 	}
 
 	mutex_lock(&q->mmap_lock);
-	q->num_buffers += allocated_buffers;
 
 	if (ret < 0) {
 		/*
@@ -2547,7 +2568,9 @@ void vb2_core_queue_release(struct vb2_queue *q)
 	__vb2_queue_free(q, q->max_num_buffers);
 	kfree(q->bufs);
 	q->bufs = NULL;
-	q->num_buffers = 0;
+	bitmap_free(q->bufs_bitmap);
+	q->bufs_bitmap = NULL;
+
 	mutex_unlock(&q->mmap_lock);
 }
 EXPORT_SYMBOL_GPL(vb2_core_queue_release);
@@ -2902,7 +2925,7 @@ static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_
 	 * Check if we need to dequeue the buffer.
 	 */
 	index = fileio->cur_index;
-	if (index >= q->num_buffers) {
+	if (!test_bit(index, q->bufs_bitmap)) {
 		struct vb2_buffer *b;
 
 		/*
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index d433bf84e30c..fc1fcd8faa64 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -346,7 +346,7 @@ struct vb2_buffer {
  *			describes the requested number of planes and sizes\[\]
  *			contains the requested plane sizes. In this case
  *			\*num_buffers are being allocated additionally to
- *			q->num_buffers. If either \*num_planes or the requested
+ *			queue buffers. If either \*num_planes or the requested
  *			sizes are invalid callback must return %-EINVAL.
  * @wait_prepare:	release any locks taken while calling vb2 functions;
  *			it is called before an ioctl needs to wait for a new
@@ -557,7 +557,7 @@ struct vb2_buf_ops {
  * @memory:	current memory type used
  * @dma_dir:	DMA mapping direction.
  * @bufs:	videobuf2 buffer structures
- * @num_buffers: number of allocated/used buffers
+ * @bufs_bitmap: bitmap to manage bufs entries.
  * @max_num_buffers: upper limit of number of allocated/used buffers
  * @queued_list: list of buffers currently queued from userspace
  * @queued_count: number of buffers queued and ready for streaming.
@@ -621,7 +621,7 @@ struct vb2_queue {
 	unsigned int			memory;
 	enum dma_data_direction		dma_dir;
 	struct vb2_buffer		**bufs;
-	unsigned int			num_buffers;
+	unsigned long			*bufs_bitmap;
 	unsigned int			max_num_buffers;
 
 	struct list_head		queued_list;
@@ -1150,7 +1150,10 @@ static inline bool vb2_fileio_is_active(struct vb2_queue *q)
  */
 static inline unsigned int vb2_get_num_buffers(struct vb2_queue *q)
 {
-	return q->num_buffers;
+	if (!q->bufs_bitmap)
+		return 0;
+
+	return bitmap_weight(q->bufs_bitmap, q->max_num_buffers);
 }
 
 /**
@@ -1253,7 +1256,13 @@ static inline void vb2_clear_last_buffer_dequeued(struct vb2_queue *q)
 static inline struct vb2_buffer *vb2_get_buffer(struct vb2_queue *q,
 						unsigned int index)
 {
-	if (index < q->num_buffers)
+	if (!q->bufs_bitmap)
+		return NULL;
+
+	if (index >= q->max_num_buffers)
+		return NULL;
+
+	if (test_bit(index, q->bufs_bitmap))
 		return q->bufs[index];
 	return NULL;
 }
-- 
2.39.2