[PATCH v8 48/53] media: core: Rework how create_buf index returned value is computed

Benjamin Gaignard
2023-09-27T15:40:46Z

When DELETE_BUFS will be introduced holes could created in bufs array.
To be able to reuse these unused indices reworking how create->index
is set is mandatory.
Let __vb2_queue_alloc() decide which first index is correct and
forward this to the caller.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
---
.../media/common/videobuf2/videobuf2-core.c | 21 ++++++++++++-------
.../media/common/videobuf2/videobuf2-v4l2.c | 20 +++++++++++-------
include/media/videobuf2-core.h | 5 ++++-
3 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 320f37e46343..b5a963030cde 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -441,15 +441,21 @@ static void vb2_queue_remove_buffer(struct vb2_buffer *vb)
*/
static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
unsigned int num_buffers, unsigned int num_planes,
- const unsigned plane_sizes[VB2_MAX_PLANES])
+ const unsigned plane_sizes[VB2_MAX_PLANES],
+ unsigned int *first_index)
{
unsigned int buffer, plane;
struct vb2_buffer *vb;
+ unsigned long index;
int ret;

/* Ensure that the number of already queue + num_buffers is below q->max_num_buffers */
num_buffers = min_t(unsigned int, num_buffers,
- q->max_num_buffers - q->num_buffers);
+ q->max_num_buffers - vb2_get_num_buffers(q));
+
+ index = vb2_get_num_buffers(q);
+
+ *first_index = index;

for (buffer = 0; buffer < num_buffers; ++buffer) {
/* Allocate vb2 buffer structures */
@@ -469,7 +475,7 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
vb->planes[plane].min_length = plane_sizes[plane];
}

- vb2_queue_add_buffer(q, vb, q->num_buffers + buffer);
+ vb2_queue_add_buffer(q, vb, index++);
call_void_bufop(q, init_buffer, vb);

/* Allocate video buffer memory for the MMAP type */
@@ -812,7 +818,7 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
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;
+ unsigned int i, first_index;
int ret = 0;

if (q->streaming) {
@@ -898,7 +904,7 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,

/* Finally, allocate buffers and video memory */
allocated_buffers =
- __vb2_queue_alloc(q, memory, num_buffers, num_planes, plane_sizes);
+ __vb2_queue_alloc(q, memory, num_buffers, num_planes, plane_sizes, &first_index);
if (allocated_buffers == 0) {
dprintk(q, 1, "memory allocation failed\n");
ret = -ENOMEM;
@@ -972,7 +978,8 @@ EXPORT_SYMBOL_GPL(vb2_core_reqbufs);
int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
unsigned int flags, unsigned int *count,
unsigned int requested_planes,
- const unsigned int requested_sizes[])
+ const unsigned int requested_sizes[],
+ unsigned int *first_index)
{
unsigned int num_planes = 0, num_buffers, allocated_buffers;
unsigned plane_sizes[VB2_MAX_PLANES] = { };
@@ -1034,7 +1041,7 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,

/* Finally, allocate buffers and video memory */
allocated_buffers = __vb2_queue_alloc(q, memory, num_buffers,
- num_planes, plane_sizes);
+ num_planes, plane_sizes, first_index);
if (allocated_buffers == 0) {
dprintk(q, 1, "memory allocation failed\n");
ret = -ENOMEM;
diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index 304163e27d10..3d2affb00d19 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -809,11 +809,16 @@ int vb2_create_bufs(struct vb2_queue *q, struct v4l2_create_buffers *create)
for (i = 0; i < requested_planes; i++)
if (requested_sizes[i] == 0)
return -EINVAL;
- return ret ? ret : vb2_core_create_bufs(q, create->memory,
- create->flags,
- &create->count,
- requested_planes,
- requested_sizes);
+ if (ret)
+ return ret;
+
+ ret = vb2_core_create_bufs(q, create->memory,
+ create->flags,
+ &create->count,
+ requested_planes,
+ requested_sizes,
+ &create->index);
+ return ret;
}
EXPORT_SYMBOL_GPL(vb2_create_bufs);

@@ -1041,15 +1046,16 @@ int vb2_ioctl_create_bufs(struct file *file, void *priv,
int res = vb2_verify_memory_type(vdev->queue, p->memory,
p->format.type);

- p->index = vdev->queue->num_buffers;
fill_buf_caps(vdev->queue, &p->capabilities);
validate_memory_flags(vdev->queue, p->memory, &p->flags);
/*
* If count == 0, then just check if memory and type are valid.
* Any -EBUSY result from vb2_verify_memory_type can be mapped to 0.
*/
- if (p->count == 0)
+ if (p->count == 0) {
+ p->index = vb2_get_num_buffers(vdev->queue);
return res != -EBUSY ? res : 0;
+ }
if (res)
return res;
if (vb2_queue_is_busy(vdev->queue, file))
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index dffb9647d4d1..d433bf84e30c 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -803,6 +803,8 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
* @count: requested buffer count.
* @requested_planes: number of planes requested.
* @requested_sizes: array with the size of the planes.
+ * @first_index: index of the first created buffer, all allocated buffers have
+ * indices in the range [first..first+count]
*
* Videobuf2 core helper to implement VIDIOC_CREATE_BUFS() operation. It is
* called internally by VB2 by an API-specific handler, like
@@ -819,7 +821,8 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
unsigned int flags, unsigned int *count,
unsigned int requested_planes,
- const unsigned int requested_sizes[]);
+ const unsigned int requested_sizes[],
+ unsigned int *first_index);

/**
* vb2_core_prepare_buf() - Pass ownership of a buffer from userspace