2023-09-04 16:27:13

by Hans Verkuil

[permalink] [raw]
Subject: Re: [PATCH v6 11/18] media: videobuf2: Be more flexible on the number of queue stored buffers

Hi Benjamin,

This patch can be folded into 11/18 to make it work properly.

vb2_core_queue_release() is also called when the file handle of the video device is
closed and it is also the owner of the currently allocated buffers. This will free
q->bufs, but queue_init isn't called a second time for non-m2m devices. So move
the allocation of q->bufs from queue_init to reqbufs/create_buffers.

And when releasing the file handle we also check if there is no owner at all:
in that case vb2_queue_release() must still be called to free q->bufs.

Signed-off-by: Hans Verkuil <[email protected]>
---
drivers/media/common/videobuf2/videobuf2-core.c | 15 +++++++++++++--
drivers/media/common/videobuf2/videobuf2-v4l2.c | 4 ++--
2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index dc7f6b59d237..202d7c80ffd2 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -859,6 +859,12 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
return 0;
}

+ if (!q->bufs) {
+ q->bufs = kcalloc(q->max_allowed_buffers, sizeof(*q->bufs), GFP_KERNEL);
+ if (!q->bufs)
+ return -ENOMEM;
+ }
+
/*
* Make sure the requested values and current defaults are sane.
*/
@@ -985,6 +991,12 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
return -ENOBUFS;
}

+ if (!q->bufs) {
+ q->bufs = kcalloc(q->max_allowed_buffers, sizeof(*q->bufs), GFP_KERNEL);
+ if (!q->bufs)
+ return -ENOMEM;
+ }
+
if (no_previous_buffers) {
if (q->waiting_in_dqbuf && *count) {
dprintk(q, 1, "another dup()ped fd is waiting for a buffer\n");
@@ -2525,8 +2537,6 @@ int vb2_core_queue_init(struct vb2_queue *q)
/* The maximum is limited by offset cookie encoding pattern */
q->max_allowed_buffers = min_t(unsigned int, q->max_allowed_buffers, BUFFER_INDEX_MASK);

- q->bufs = kcalloc(q->max_allowed_buffers, sizeof(*q->bufs), GFP_KERNEL);
-
if (q->buf_struct_size == 0)
q->buf_struct_size = sizeof(struct vb2_buffer);

@@ -2552,6 +2562,7 @@ void vb2_core_queue_release(struct vb2_queue *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 8ba658ad9891..104fc5c4f574 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -1148,7 +1148,7 @@ 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;
}
@@ -1276,7 +1276,7 @@ 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;

--
2.40.1



2023-09-04 18:16:35

by Hans Verkuil

[permalink] [raw]
Subject: Re: [PATCH v6 11/18] media: videobuf2: Be more flexible on the number of queue stored buffers

A follow-up to my follow-up...

I realized that it is wise to do the allocation with mmap_lock held, since that is also
held when freeing q->bufs.

Signed-off-by: Hans Verkuil <[email protected]>
---
.../media/common/videobuf2/videobuf2-core.c | 28 +++++++++----------
1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index fe15e583b52a..dd25937c6dc8 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -818,7 +818,7 @@ 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");
@@ -859,12 +859,6 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
return 0;
}

- if (!q->bufs) {
- q->bufs = kcalloc(q->max_allowed_buffers, sizeof(*q->bufs), GFP_KERNEL);
- if (!q->bufs)
- return -ENOMEM;
- }
-
/*
* Make sure the requested values and current defaults are sane.
*/
@@ -877,8 +871,14 @@ int vb2_core_reqbufs(struct vb2_queue *q, enum vb2_memory memory,
* in the queue_setup op.
*/
mutex_lock(&q->mmap_lock);
+ if (!q->bufs)
+ q->bufs = kcalloc(q->max_allowed_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);

/*
@@ -984,19 +984,13 @@ 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 == q->max_allowed_buffers) {
dprintk(q, 1, "maximum number of buffers already allocated\n");
return -ENOBUFS;
}

- if (!q->bufs) {
- q->bufs = kcalloc(q->max_allowed_buffers, sizeof(*q->bufs), GFP_KERNEL);
- if (!q->bufs)
- return -ENOMEM;
- }
-
if (no_previous_buffers) {
if (q->waiting_in_dqbuf && *count) {
dprintk(q, 1, "another dup()ped fd is waiting for a buffer\n");
@@ -1009,7 +1003,13 @@ 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_allowed_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 {
--
2.40.1