[PATCH v8 12/53] media: videobuf2: Be more flexible on the number of queue stored buffers

Benjamin Gaignard
2023-09-27T15:37:31Z

Add 'max_num_buffers' field in vb2_queue struct to let drivers decide
how many buffers could be stored in a queue.
This require 'bufs' array to be allocated at queue init time and freed
when releasing the queue.
By default VB2_MAX_FRAME remains the limit.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
---
.../media/common/videobuf2/videobuf2-core.c | 41 +++++++++++++++----
.../media/common/videobuf2/videobuf2-v4l2.c | 4 +-
include/media/videobuf2-core.h | 4 +-
3 files changed, 37 insertions(+), 12 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 17b0dafacaab..023e00aa4848 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -415,7 +415,7 @@ 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 >= VB2_MAX_FRAME || q->bufs[index]);
+ WARN_ON(index >= q->max_num_buffers || q->bufs[index]);

q->bufs[index] = vb;
vb->index = index;
@@ -447,9 +447,9 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
struct vb2_buffer *vb;
int ret;

- /* Ensure that q->num_buffers+num_buffers is below VB2_MAX_FRAME */
+ /* Ensure that the number of already queue + num_buffers is below q->max_num_buffers */
num_buffers = min_t(unsigned int, num_buffers,
- VB2_MAX_FRAME - q->num_buffers);
+ q->max_num_buffers - q->num_buffers);

for (buffer = 0; buffer < num_buffers; ++buffer) {
/* Allocate vb2 buffer structures */
@@ -808,7 +808,7 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
unsigned plane_sizes[VB2_MAX_PLANES] = { };
bool non_coherent_mem = flags & V4L2_MEMORY_FLAG_NON_COHERENT;
unsigned int i;
- int ret;
+ int ret = 0;

if (q->streaming) {
dprintk(q, 1, "streaming active\n");
@@ -852,17 +852,22 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
/*
* Make sure the requested values and current defaults are sane.
*/
- WARN_ON(q->min_buffers_needed > VB2_MAX_FRAME);
num_buffers = max_t(unsigned int, *count, q->min_buffers_needed);
- num_buffers = min_t(unsigned int, num_buffers, VB2_MAX_FRAME);
+ num_buffers = min_t(unsigned int, num_buffers, q->max_num_buffers);
memset(q->alloc_devs, 0, sizeof(q->alloc_devs));
/*
* Set this now to ensure that drivers see the correct q->memory value
* in the queue_setup op.
*/
mutex_lock(&q->mmap_lock);
+ if (!q->bufs)
+ q->bufs = kcalloc(q->max_num_buffers, sizeof(*q->bufs), GFP_KERNEL);
+ if (!q->bufs)
+ ret = -ENOMEM;
q->memory = memory;
mutex_unlock(&q->mmap_lock);
+ if (ret)
+ return ret;
set_queue_coherency(q, non_coherent_mem);

/*
@@ -968,9 +973,9 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
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;
+ int ret = 0;

- if (q->num_buffers == VB2_MAX_FRAME) {
+ if (q->num_buffers == q->max_num_buffers) {
dprintk(q, 1, "maximum number of buffers already allocated\n");
return -ENOBUFS;
}
@@ -987,7 +992,13 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
*/
mutex_lock(&q->mmap_lock);
q->memory = memory;
+ if (!q->bufs)
+ q->bufs = kcalloc(q->max_num_buffers, sizeof(*q->bufs), GFP_KERNEL);
+ if (!q->bufs)
+ ret = -ENOMEM;
mutex_unlock(&q->mmap_lock);
+ if (ret)
+ return ret;
q->waiting_for_buffers = !q->is_output;
set_queue_coherency(q, non_coherent_mem);
} else {
@@ -999,7 +1010,7 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
return -EINVAL;
}

- num_buffers = min(*count, VB2_MAX_FRAME - q->num_buffers);
+ num_buffers = min(*count, q->max_num_buffers - q->num_buffers);

if (requested_planes && requested_sizes) {
num_planes = requested_planes;
@@ -2467,6 +2478,10 @@ int vb2_core_queue_init(struct vb2_queue *q)
WARN_ON(!q->ops->buf_queue))
return -EINVAL;

+ if (WARN_ON(q->max_num_buffers > BUFFER_INDEX_MASK + 1) ||
+ WARN_ON(q->min_buffers_needed > q->max_num_buffers))
+ return -EINVAL;
+
if (WARN_ON(q->requires_requests && !q->supports_requests))
return -EINVAL;

@@ -2489,6 +2504,12 @@ int vb2_core_queue_init(struct vb2_queue *q)

q->memory = VB2_MEMORY_UNKNOWN;

+ if (!q->max_num_buffers)
+ q->max_num_buffers = VB2_MAX_FRAME;
+
+ /* The maximum is limited by offset cookie encoding pattern */
+ q->max_num_buffers = min_t(unsigned int, q->max_num_buffers, BUFFER_INDEX_MASK + 1);
+
if (q->buf_struct_size == 0)
q->buf_struct_size = sizeof(struct vb2_buffer);

@@ -2513,6 +2534,8 @@ void vb2_core_queue_release(struct vb2_queue *q)
__vb2_queue_cancel(q);
mutex_lock(&q->mmap_lock);
__vb2_queue_free(q, q->num_buffers);
+ kfree(q->bufs);
+ q->bufs = NULL;
mutex_unlock(&q->mmap_lock);
}
EXPORT_SYMBOL_GPL(vb2_core_queue_release);
diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index 3395e702ad1f..278ea1107b01 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -1156,7 +1156,7 @@ int _vb2_fop_release(struct file *file, struct mutex *lock)

if (lock)
mutex_lock(lock);
- if (file->private_data == vdev->queue->owner) {
+ if (!vdev->queue->owner || file->private_data == vdev->queue->owner) {
vb2_queue_release(vdev->queue);
vdev->queue->owner = NULL;
}
@@ -1284,7 +1284,7 @@ void vb2_video_unregister_device(struct video_device *vdev)
*/
get_device(&vdev->dev);
video_unregister_device(vdev);
- if (vdev->queue && vdev->queue->owner) {
+ if (vdev->queue) {
struct mutex *lock = vdev->queue->lock ?
vdev->queue->lock : vdev->lock;

diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index cd3ff1cd759d..1d6d68e8a711 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -558,6 +558,7 @@ struct vb2_buf_ops {
* @dma_dir: DMA mapping direction.
* @bufs: videobuf2 buffer structures
* @num_buffers: number of allocated/used buffers
+ * @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.
* @owned_by_drv_count: number of buffers owned by the driver
@@ -619,8 +620,9 @@ struct vb2_queue {
struct mutex mmap_lock;
unsigned int memory;
enum dma_data_direction dma_dir;
- struct vb2_buffer *bufs[VB2_MAX_FRAME];
+ struct vb2_buffer **bufs;
unsigned int num_buffers;
+ unsigned int max_num_buffers;

struct list_head queued_list;
unsigned int queued_count;