Re: [PATCH v14 43/56] media: videobuf2: Be more flexible on the number of queue stored buffers
From: Benjamin Gaignard
Date: Mon Nov 06 2023 - 09:29:48 EST
Le 02/11/2023 à 09:17, Hans Verkuil a écrit :
Hi Benjamin,
After a lot of testing yesterday I discovered that this patch introduces a
bug. After this bug, running the test-media script will result in a lot of
unbalanced counters messages:
[Wed Nov 1 16:40:48 2023] videobuf2_common: unbalanced counters for queue ffff888115a07f00, buffer 11:
[Wed Nov 1 16:40:48 2023] videobuf2_common: buf_init: 1 buf_cleanup: 0
[Wed Nov 1 16:40:48 2023] videobuf2_common: alloc: 1 put: 0
[Wed Nov 1 16:40:48 2023] videobuf2_common: get_dmabuf: 0 num_users: 0
Apparently buf_init is called, but not buf_cleanup.
I also get loads of kmemleak reports:
unreferenced object 0xffff88800eae6800 (size 2048):
comm "v4l2-compliance", pid 652, jiffies 4294937190 (age 149.650s)
hex dump (first 32 bytes):
e0 52 18 0c 81 88 ff ff 00 00 00 00 02 00 00 00 .R..............
01 00 00 00 01 00 00 00 20 2f d3 f3 3e 00 00 00 ........ /..>...
backtrace:
[<ffffffffacbdb08b>] __kmalloc+0x4b/0x150
[<ffffffffc01df77a>] __vb2_queue_alloc+0x11a/0xca0 [videobuf2_common]
[<ffffffffc01e74f5>] vb2_core_reqbufs+0x735/0xfd0 [videobuf2_common]
[<ffffffffc046ca71>] v4l2_m2m_ioctl_reqbufs+0xc1/0x1b0 [v4l2_mem2mem]
[<ffffffffc0231520>] __video_do_ioctl+0x8d0/0xc20 [videodev]
[<ffffffffc0232bcc>] video_usercopy+0x48c/0xd00 [videodev]
[<ffffffffc021e2ff>] v4l2_ioctl+0x17f/0x1f0 [videodev]
[<ffffffffacd758ce>] __do_compat_sys_ioctl+0x13e/0x1d0
[<ffffffffae7df992>] __do_fast_syscall_32+0x62/0xe0
[<ffffffffae7dfb4f>] do_fast_syscall_32+0x2f/0x70
[<ffffffffaea012ed>] entry_SYSCALL_compat_after_hwframe+0x45/0x4d
Very likely the same issue.
Unfortunately, the build script does not yet check for issues like this,
you have to manually inspect the test-media logs (found in the logs directory
after the run). It's on my TODO list.
The issue is in vb2_core_queue_release(), the patch shouldn't change
__vb2_queue_free() second parameter.
When removing this change, unbalanced messages disappear.
Regards,
Benjamin
Regards,
Hans
On 31/10/2023 17:30, Benjamin Gaignard wrote:
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@xxxxxxxxxxxxx>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
---
.../media/common/videobuf2/videobuf2-core.c | 41 +++++++++++++++----
.../media/common/videobuf2/videobuf2-v4l2.c | 6 +--
include/media/videobuf2-core.h | 10 ++++-
3 files changed, 44 insertions(+), 13 deletions(-)
diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index c5c5ae4d213d..72ef7179d80a 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -416,7 +416,7 @@ 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;
@@ -449,9 +449,9 @@ 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 */
@@ -813,7 +813,7 @@ 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");
@@ -857,17 +857,22 @@ 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);
/*
@@ -976,7 +981,7 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
bool no_previous_buffers = !q_num_bufs;
int ret = 0;
- if (q_num_bufs == VB2_MAX_FRAME) {
+ if (q->num_buffers == q->max_num_buffers) {
dprintk(q, 1, "maximum number of buffers already allocated\n");
return -ENOBUFS;
}
@@ -993,7 +998,13 @@ 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 {
@@ -1005,7 +1016,7 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
return -EINVAL;
}
- num_buffers = min(*count, VB2_MAX_FRAME - q_num_bufs);
+ num_buffers = min(*count, q->max_num_buffers - q_num_bufs);
if (requested_planes && requested_sizes) {
num_planes = requested_planes;
@@ -2465,6 +2476,12 @@ int vb2_core_queue_init(struct vb2_queue *q)
/*
* Sanity check
*/
+ 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, MAX_BUFFER_INDEX);
+
if (WARN_ON(!q) ||
WARN_ON(!q->ops) ||
WARN_ON(!q->mem_ops) ||
@@ -2474,6 +2491,10 @@ int vb2_core_queue_init(struct vb2_queue *q)
WARN_ON(!q->ops->buf_queue))
return -EINVAL;
+ if (WARN_ON(q->max_num_buffers > MAX_BUFFER_INDEX) ||
+ WARN_ON(q->min_buffers_needed > q->max_num_buffers))
+ return -EINVAL;
+
if (WARN_ON(q->requires_requests && !q->supports_requests))
return -EINVAL;
@@ -2519,7 +2540,9 @@ void vb2_core_queue_release(struct vb2_queue *q)
__vb2_cleanup_fileio(q);
__vb2_queue_cancel(q);
mutex_lock(&q->mmap_lock);
- __vb2_queue_free(q, vb2_get_num_buffers(q));
+ __vb2_queue_free(q, q->max_num_buffers);
+ kfree(q->bufs);
+ q->bufs = NULL;
q->num_buffers = 0;
mutex_unlock(&q->mmap_lock);
}
diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
index 7d798fb15c0b..f3cf4b235c1f 100644
--- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
+++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
@@ -627,7 +627,7 @@ struct vb2_buffer *vb2_find_buffer(struct vb2_queue *q, u64 timestamp)
* 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 < vb2_get_num_buffers(q); i++) {
+ for (i = 0; i < q->max_num_buffers; i++) {
vb2 = vb2_get_buffer(q, i);
if (!vb2)
@@ -1142,7 +1142,7 @@ 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;
}
@@ -1270,7 +1270,7 @@ 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 8f9d9e4af5b1..e77a397195f2 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;
@@ -1248,6 +1250,12 @@ 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 (!q->bufs)
+ return NULL;
+
+ if (index >= q->max_num_buffers)
+ return NULL;
+
if (index < q->num_buffers)
return q->bufs[index];
return NULL;