[PATCH v11 05/56] media: videobuf2: Access vb2_queue bufs array through helper functions

From: Benjamin Gaignard
Date: Thu Oct 12 2023 - 07:47:15 EST

This patch adds 2 helpers functions to add and remove vb2 buffers
from a queue. With these 2 and vb2_get_buffer(), bufs field of
struct vb2_queue becomes like a private member of the structure.

After each call to vb2_get_buffer() we need to be sure that we get
a valid pointer in preparation for when buffers can be deleted.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxxxxx>
---
.../media/common/videobuf2/videobuf2-core.c | 151 +++++++++++++-----
.../media/common/videobuf2/videobuf2-v4l2.c | 51 ++++--
2 files changed, 146 insertions(+), 56 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 968b7c0e7934..66d0f42f5691 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -408,6 +408,31 @@ static void init_buffer_cache_hints(struct vb2_queue *q, struct vb2_buffer *vb)
vb->skip_cache_sync_on_finish = 1;
}

+/**
+ * vb2_queue_add_buffer() - add a buffer to a queue
+ * @q: pointer to &struct vb2_queue with videobuf2 queue.
+ * @vb: pointer to &struct vb2_buffer to be added to the queue.
+ * @index: index where add vb2_buffer in the queue
+ */
+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]);
+
+ q->bufs[index] = vb;
+ vb->index = index;
+ vb->vb2_queue = q;
+}
+
+/**
+ * vb2_queue_remove_buffer() - remove a buffer from a queue
+ * @vb: pointer to &struct vb2_buffer to be removed from the queue.
+ */
+static void vb2_queue_remove_buffer(struct vb2_buffer *vb)
+{
+ vb->vb2_queue->bufs[vb->index] = NULL;
+ vb->vb2_queue = NULL;
+}
+
/*
* __vb2_queue_alloc() - allocate vb2 buffer structures and (for MMAP type)
* video buffer memory for all buffers/planes on the queue and initializes the
@@ -436,9 +461,7 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
}

vb->state = VB2_BUF_STATE_DEQUEUED;
- vb->vb2_queue = q;
vb->num_planes = num_planes;
- vb->index = q->num_buffers + buffer;
vb->type = q->type;
vb->memory = memory;
init_buffer_cache_hints(q, vb);
@@ -446,9 +469,9 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
vb->planes[plane].length = plane_sizes[plane];
vb->planes[plane].min_length = plane_sizes[plane];
}
- call_void_bufop(q, init_buffer, vb);

- q->bufs[vb->index] = vb;
+ 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 */
if (memory == VB2_MEMORY_MMAP) {
@@ -456,7 +479,7 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
if (ret) {
dprintk(q, 1, "failed allocating memory for buffer %d\n",
buffer);
- q->bufs[vb->index] = NULL;
+ vb2_queue_remove_buffer(vb);
kfree(vb);
break;
}
@@ -471,7 +494,7 @@ static int __vb2_queue_alloc(struct vb2_queue *q, enum vb2_memory memory,
dprintk(q, 1, "buffer %d %p initialization failed\n",
buffer, vb);
__vb2_buf_mem_free(vb);
- q->bufs[vb->index] = NULL;
+ vb2_queue_remove_buffer(vb);
kfree(vb);
break;
}
@@ -494,7 +517,7 @@ static void __vb2_free_mem(struct vb2_queue *q, unsigned int buffers)

for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
++buffer) {
- vb = q->bufs[buffer];
+ vb = vb2_get_buffer(q, buffer);
if (!vb)
continue;

@@ -522,7 +545,7 @@ static void __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
/* Call driver-provided cleanup function for each buffer, if provided */
for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
++buffer) {
- struct vb2_buffer *vb = q->bufs[buffer];
+ struct vb2_buffer *vb = vb2_get_buffer(q, buffer);

if (vb && vb->planes[0].mem_priv)
call_void_vb_qop(vb, buf_cleanup, vb);
@@ -563,15 +586,20 @@ static void __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
q->cnt_unprepare_streaming = 0;
}
for (buffer = 0; buffer < q->num_buffers; ++buffer) {
- struct vb2_buffer *vb = q->bufs[buffer];
- bool unbalanced = vb->cnt_mem_alloc != vb->cnt_mem_put ||
- vb->cnt_mem_prepare != vb->cnt_mem_finish ||
- vb->cnt_mem_get_userptr != vb->cnt_mem_put_userptr ||
- vb->cnt_mem_attach_dmabuf != vb->cnt_mem_detach_dmabuf ||
- vb->cnt_mem_map_dmabuf != vb->cnt_mem_unmap_dmabuf ||
- vb->cnt_buf_queue != vb->cnt_buf_done ||
- vb->cnt_buf_prepare != vb->cnt_buf_finish ||
- vb->cnt_buf_init != vb->cnt_buf_cleanup;
+ struct vb2_buffer *vb = vb2_get_buffer(q, buffer);
+ bool unbalanced;
+
+ if (!vb)
+ continue;
+
+ unbalanced = vb->cnt_mem_alloc != vb->cnt_mem_put ||
+ vb->cnt_mem_prepare != vb->cnt_mem_finish ||
+ vb->cnt_mem_get_userptr != vb->cnt_mem_put_userptr ||
+ vb->cnt_mem_attach_dmabuf != vb->cnt_mem_detach_dmabuf ||
+ vb->cnt_mem_map_dmabuf != vb->cnt_mem_unmap_dmabuf ||
+ vb->cnt_buf_queue != vb->cnt_buf_done ||
+ vb->cnt_buf_prepare != vb->cnt_buf_finish ||
+ vb->cnt_buf_init != vb->cnt_buf_cleanup;

if (unbalanced) {
pr_info("unbalanced counters for queue %p, buffer %d:\n",
@@ -611,8 +639,13 @@ static void __vb2_queue_free(struct vb2_queue *q, unsigned int buffers)
/* Free vb2 buffers */
for (buffer = q->num_buffers - buffers; buffer < q->num_buffers;
++buffer) {
- kfree(q->bufs[buffer]);
- q->bufs[buffer] = NULL;
+ struct vb2_buffer *vb = vb2_get_buffer(q, buffer);
+
+ if (!vb)
+ continue;
+
+ vb2_queue_remove_buffer(vb);
+ kfree(vb);
}

q->num_buffers -= buffers;
@@ -648,7 +681,12 @@ static bool __buffers_in_use(struct vb2_queue *q)
{
unsigned int buffer;
for (buffer = 0; buffer < q->num_buffers; ++buffer) {
- if (vb2_buffer_in_use(q, q->bufs[buffer]))
+ struct vb2_buffer *vb = vb2_get_buffer(q, buffer);
+
+ if (!vb)
+ continue;
+
+ if (vb2_buffer_in_use(q, vb))
return true;
}
return false;
@@ -1633,7 +1671,11 @@ static int vb2_start_streaming(struct vb2_queue *q)
* correctly return them to vb2.
*/
for (i = 0; i < q->num_buffers; ++i) {
- vb = q->bufs[i];
+ vb = vb2_get_buffer(q, i);
+
+ if (!vb)
+ continue;
+
if (vb->state == VB2_BUF_STATE_ACTIVE)
vb2_buffer_done(vb, VB2_BUF_STATE_QUEUED);
}
@@ -2034,12 +2076,18 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
* to vb2 in stop_streaming().
*/
if (WARN_ON(atomic_read(&q->owned_by_drv_count))) {
- for (i = 0; i < q->num_buffers; ++i)
- if (q->bufs[i]->state == VB2_BUF_STATE_ACTIVE) {
- pr_warn("driver bug: stop_streaming operation is leaving buf %p in active state\n",
- q->bufs[i]);
- vb2_buffer_done(q->bufs[i], VB2_BUF_STATE_ERROR);
+ for (i = 0; i < q->num_buffers; ++i) {
+ struct vb2_buffer *vb = vb2_get_buffer(q, i);
+
+ if (!vb)
+ continue;
+
+ if (vb->state == VB2_BUF_STATE_ACTIVE) {
+ pr_warn("driver bug: stop_streaming operation is leaving buffer %u in active state\n",
+ vb->index);
+ vb2_buffer_done(vb, VB2_BUF_STATE_ERROR);
}
+ }
/* Must be zero now */
WARN_ON(atomic_read(&q->owned_by_drv_count));
}
@@ -2073,9 +2121,14 @@ static void __vb2_queue_cancel(struct vb2_queue *q)
* be changed, so we can't move the buf_finish() to __vb2_dqbuf().
*/
for (i = 0; i < q->num_buffers; ++i) {
- struct vb2_buffer *vb = q->bufs[i];
- struct media_request *req = vb->req_obj.req;
+ struct vb2_buffer *vb;
+ struct media_request *req;

+ vb = vb2_get_buffer(q, i);
+ if (!vb)
+ continue;
+
+ req = vb->req_obj.req;
/*
* If a request is associated with this buffer, then
* call buf_request_cancel() to give the driver to complete()
@@ -2224,10 +2277,12 @@ static int __find_plane_by_offset(struct vb2_queue *q, unsigned long offset,
buffer = (offset >> PLANE_INDEX_SHIFT) & BUFFER_INDEX_MASK;
*plane = (offset >> PAGE_SHIFT) & PLANE_INDEX_MASK;

- if (buffer >= q->num_buffers || *plane >= q->bufs[buffer]->num_planes)
+ *vb = vb2_get_buffer(q, buffer);
+ if (!*vb)
+ return -EINVAL;
+ if (*plane >= (*vb)->num_planes)
return -EINVAL;

- *vb = q->bufs[buffer];
return 0;
}

@@ -2615,6 +2670,7 @@ struct vb2_fileio_data {
static int __vb2_init_fileio(struct vb2_queue *q, int read)
{
struct vb2_fileio_data *fileio;
+ struct vb2_buffer *vb;
int i, ret;
unsigned int count = 0;

@@ -2665,11 +2721,18 @@ static int __vb2_init_fileio(struct vb2_queue *q, int read)
if (ret)
goto err_kfree;

+ /*
+ * Userspace can never add or delete buffers later, so there
+ * will never be holes. It is safe to assume that vb2_get_buffer(q, 0)
+ * will always return a valid vb pointer
+ */
+ vb = vb2_get_buffer(q, 0);
+
/*
* Check if plane_count is correct
* (multiplane buffers are not supported).
*/
- if (q->bufs[0]->num_planes != 1) {
+ if (vb->num_planes != 1) {
ret = -EBUSY;
goto err_reqbufs;
}
@@ -2678,12 +2741,15 @@ static int __vb2_init_fileio(struct vb2_queue *q, int read)
* Get kernel address of each buffer.
*/
for (i = 0; i < q->num_buffers; i++) {
- fileio->bufs[i].vaddr = vb2_plane_vaddr(q->bufs[i], 0);
+ vb = vb2_get_buffer(q, i);
+ WARN_ON_ONCE(!vb);
+
+ fileio->bufs[i].vaddr = vb2_plane_vaddr(vb, 0);
if (fileio->bufs[i].vaddr == NULL) {
ret = -EINVAL;
goto err_reqbufs;
}
- fileio->bufs[i].size = vb2_plane_size(q->bufs[i], 0);
+ fileio->bufs[i].size = vb2_plane_size(vb, 0);
}

/*
@@ -2811,15 +2877,17 @@ static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_

fileio->cur_index = index;
buf = &fileio->bufs[index];
- b = q->bufs[index];
+
+ /* b can never be NULL when using fileio. */
+ b = vb2_get_buffer(q, index);

/*
* Get number of bytes filled by the driver
*/
buf->pos = 0;
buf->queued = 0;
- buf->size = read ? vb2_get_plane_payload(q->bufs[index], 0)
- : vb2_plane_size(q->bufs[index], 0);
+ buf->size = read ? vb2_get_plane_payload(b, 0)
+ : vb2_plane_size(b, 0);
/* Compensate for data_offset on read in the multiplanar case. */
if (is_multiplanar && read &&
b->planes[0].data_offset < buf->size) {
@@ -2862,7 +2930,8 @@ static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_
* Queue next buffer if required.
*/
if (buf->pos == buf->size || (!read && fileio->write_immediately)) {
- struct vb2_buffer *b = q->bufs[index];
+ /* b can never be NULL when using fileio. */
+ struct vb2_buffer *b = vb2_get_buffer(q, index);

/*
* Check if this is the last buffer to read.
@@ -2889,7 +2958,7 @@ static size_t __vb2_perform_fileio(struct vb2_queue *q, char __user *data, size_
*/
buf->pos = 0;
buf->queued = 1;
- buf->size = vb2_plane_size(q->bufs[index], 0);
+ buf->size = vb2_plane_size(b, 0);
fileio->q_count += 1;
/*
* If we are queuing up buffers for the first time, then
@@ -2960,7 +3029,9 @@ static int vb2_thread(void *data)
* Call vb2_dqbuf to get buffer back.
*/
if (prequeue) {
- vb = q->bufs[index++];
+ vb = vb2_get_buffer(q, index++);
+ if (!vb)
+ continue;
prequeue--;
} else {
call_void_qop(q, wait_finish, q);
@@ -2969,7 +3040,7 @@ static int vb2_thread(void *data)
call_void_qop(q, wait_prepare, q);
dprintk(q, 5, "file io: vb2_dqbuf result: %d\n", ret);
if (!ret)
- vb = q->bufs[index];
+ vb = vb2_get_buffer(q, index);
}
if (ret || threadio->stop)
break;
diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index 697c8a9f98cd..3395e702ad1f 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -383,9 +383,9 @@ static int vb2_queue_or_prepare_buf(struct vb2_queue *q, struct media_device *md
return -EINVAL;
}

- if (q->bufs[b->index] == NULL) {
- /* Should never happen */
- dprintk(q, 1, "%s: buffer is NULL\n", opname);
+ vb = vb2_get_buffer(q, b->index);
+ if (!vb) {
+ dprintk(q, 1, "%s: buffer %u is NULL\n", opname, b->index);
return -EINVAL;
}

@@ -394,7 +394,6 @@ static int vb2_queue_or_prepare_buf(struct vb2_queue *q, struct media_device *md
return -EINVAL;
}

- vb = q->bufs[b->index];
vbuf = to_vb2_v4l2_buffer(vb);
ret = __verify_planes_array(vb, b);
if (ret)
@@ -628,11 +627,22 @@ static const struct vb2_buf_ops v4l2_buf_ops = {
struct vb2_buffer *vb2_find_buffer(struct vb2_queue *q, u64 timestamp)
{
unsigned int i;
+ struct vb2_buffer *vb2;

- for (i = 0; i < q->num_buffers; i++)
- if (q->bufs[i]->copied_timestamp &&
- q->bufs[i]->timestamp == timestamp)
- return vb2_get_buffer(q, i);
+ /*
+ * 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++) {
+ vb2 = vb2_get_buffer(q, i);
+
+ if (!vb2)
+ continue;
+
+ if (vb2->copied_timestamp &&
+ vb2->timestamp == timestamp)
+ return vb2;
+ }
return NULL;
}
EXPORT_SYMBOL_GPL(vb2_find_buffer);
@@ -660,11 +670,12 @@ int vb2_querybuf(struct vb2_queue *q, struct v4l2_buffer *b)
return -EINVAL;
}

- if (b->index >= q->num_buffers) {
- dprintk(q, 1, "buffer index out of range\n");
+ vb = vb2_get_buffer(q, b->index);
+ if (!vb) {
+ dprintk(q, 1, "can't find the requested buffer %u\n", b->index);
return -EINVAL;
}
- vb = q->bufs[b->index];
+
ret = __verify_planes_array(vb, b);
if (!ret)
vb2_core_querybuf(q, vb, b);
@@ -734,11 +745,11 @@ int vb2_prepare_buf(struct vb2_queue *q, struct media_device *mdev,
if (b->flags & V4L2_BUF_FLAG_REQUEST_FD)
return -EINVAL;

- if (b->index >= q->num_buffers) {
- dprintk(q, 1, "buffer index out of range\n");
+ vb = vb2_get_buffer(q, b->index);
+ if (!vb) {
+ dprintk(q, 1, "can't find the requested buffer %u\n", b->index);
return -EINVAL;
}
- vb = q->bufs[b->index];

ret = vb2_queue_or_prepare_buf(q, mdev, b, true, NULL);

@@ -822,7 +833,11 @@ int vb2_qbuf(struct vb2_queue *q, struct media_device *mdev,
dprintk(q, 1, "buffer index out of range\n");
return -EINVAL;
}
- vb = q->bufs[b->index];
+ vb = vb2_get_buffer(q, b->index);
+ if (!vb) {
+ dprintk(q, 1, "can't find the requested buffer %u\n", b->index);
+ return -EINVAL;
+ }

ret = vb2_queue_or_prepare_buf(q, mdev, b, false, &req);
if (ret)
@@ -893,7 +908,11 @@ int vb2_expbuf(struct vb2_queue *q, struct v4l2_exportbuffer *eb)
dprintk(q, 1, "buffer index out of range\n");
return -EINVAL;
}
- vb = q->bufs[eb->index];
+ vb = vb2_get_buffer(q, eb->index);
+ if (!vb) {
+ dprintk(q, 1, "can't find the requested buffer %u\n", eb->index);
+ return -EINVAL;
+ }

return vb2_core_expbuf(q, &eb->fd, eb->type, vb,
eb->plane, eb->flags);
--
2.39.2