Re: [PATCH v6 11/18] media: videobuf2: Be more flexible on the number of queue stored buffers
From: Benjamin Gaignard
Date: Mon Sep 04 2023 - 07:46:46 EST
Le 04/09/2023 à 13:24, Hans Verkuil a écrit :
Hi Benjamin,
On 01/09/2023 14:44, Benjamin Gaignard wrote:
Add 'max_allowed_buffers' field in vb2_queue struct to let drivers decide
how many buffers could be stored in a queue.
This request '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>
---
.../media/common/videobuf2/videobuf2-core.c | 25 +++++++++++++------
include/media/videobuf2-core.h | 4 ++-
2 files changed, 20 insertions(+), 9 deletions(-)
This patch breaks v4l2-compliance. I see lots of issues when running the
test-media script in v4l-utils, contrib/test, among them memory leaks
and use-after-free.
I actually tested using virtme with the build scripts, but that in turn
calls the test-media script in a qemu environment, and it is at the moment
a bit tricky to set up, unless you run a debian 12 distro.
I will email the test logs directly to you since they are a bit large (>5000 lines).
I will try to reproduce this error on my side to fix it.
Regards,
Benjamin
Regards,
Hans
diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 15b583ce0c69..dc7f6b59d237 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -411,7 +411,7 @@ static void init_buffer_cache_hints(struct vb2_queue *q, struct vb2_buffer *vb)
*/
static bool vb2_queue_add_buffer(struct vb2_queue *q, struct vb2_buffer *vb, unsigned int index)
{
- if (index < VB2_MAX_FRAME && !q->bufs[index]) {
+ if (index < q->max_allowed_buffers && !q->bufs[index]) {
q->bufs[index] = vb;
vb->index = index;
vb->vb2_queue = q;
@@ -428,7 +428,7 @@ static bool vb2_queue_add_buffer(struct vb2_queue *q, struct vb2_buffer *vb, uns
*/
static void vb2_queue_remove_buffer(struct vb2_queue *q, struct vb2_buffer *vb)
{
- if (vb->index < VB2_MAX_FRAME) {
+ if (vb->index < q->max_allowed_buffers) {
q->bufs[vb->index] = NULL;
vb->vb2_queue = NULL;
}
@@ -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 q->num_buffers+num_buffers is below q->max_allowed_buffers */
num_buffers = min_t(unsigned int, num_buffers,
- VB2_MAX_FRAME - q->num_buffers);
+ q->max_allowed_buffers - q->num_buffers);
for (buffer = 0; buffer < num_buffers; ++buffer) {
/* Allocate vb2 buffer structures */
@@ -862,9 +862,9 @@ 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);
+ WARN_ON(q->min_buffers_needed > q->max_allowed_buffers);
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_allowed_buffers);
memset(q->alloc_devs, 0, sizeof(q->alloc_devs));
/*
* Set this now to ensure that drivers see the correct q->memory value
@@ -980,7 +980,7 @@ int vb2_core_create_bufs(struct vb2_queue *q, enum vb2_memory memory,
bool no_previous_buffers = !q->num_buffers;
int ret;
- if (q->num_buffers == VB2_MAX_FRAME) {
+ if (q->num_buffers == q->max_allowed_buffers) {
dprintk(q, 1, "maximum number of buffers already allocated\n");
return -ENOBUFS;
}
@@ -1009,7 +1009,7 @@ 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_allowed_buffers - q->num_buffers);
if (requested_planes && requested_sizes) {
num_planes = requested_planes;
@@ -2519,6 +2519,14 @@ int vb2_core_queue_init(struct vb2_queue *q)
q->memory = VB2_MEMORY_UNKNOWN;
+ if (!q->max_allowed_buffers)
+ q->max_allowed_buffers = VB2_MAX_FRAME;
+
+ /* 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);
@@ -2543,6 +2551,7 @@ 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);
mutex_unlock(&q->mmap_lock);
}
EXPORT_SYMBOL_GPL(vb2_core_queue_release);
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index cd3ff1cd759d..97153c69583f 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_allowed_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_allowed_buffers;
struct list_head queued_list;
unsigned int queued_count;