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Message-ID: <20230321181610.GE20234@pendragon.ideasonboard.com>
Date: Tue, 21 Mar 2023 20:16:10 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Benjamin Gaignard <benjamin.gaignard@...labora.com>
Cc: tfiga@...omium.org, m.szyprowski@...sung.com, mchehab@...nel.org,
ming.qian@....com, shijie.qin@....com, eagle.zhou@....com,
bin.liu@...iatek.com, matthias.bgg@...il.com,
angelogioacchino.delregno@...labora.com, tiffany.lin@...iatek.com,
andrew-ct.chen@...iatek.com, yunfei.dong@...iatek.com,
stanimir.k.varbanov@...il.com, quic_vgarodia@...cinc.com,
agross@...nel.org, andersson@...nel.org, konrad.dybcio@...aro.org,
ezequiel@...guardiasur.com.ar, p.zabel@...gutronix.de,
daniel.almeida@...labora.com, hverkuil-cisco@...all.nl,
jernel@...nel.org, linux-media@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-mediatek@...ts.infradead.org, linux-arm-msm@...r.kernel.org,
linux-rockchip@...ts.infradead.org, kernel@...labora.com
Subject: Re: [PATCH v2 2/8] media: videobuf2: Make bufs array dynamic
allocated
Hi Benjamin,
Thank you for the patch.
On Tue, Mar 21, 2023 at 11:28:49AM +0100, Benjamin Gaignard wrote:
> Instead of a static array change bufs to a dynamically allocated array.
> This will allow to store more video buffer if needed.
> Protect the array with a spinlock.
I think I asked in the review of v1 why we couldn't use the kernel
IDA/IDR APIs to allocate buffer IDs and register buffers, but I don't
think I've received a reply. Wouldn't it be better than rolling out our
own mechanism ?
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...labora.com>
> ---
> .../media/common/videobuf2/videobuf2-core.c | 8 +++
> include/media/videobuf2-core.h | 49 ++++++++++++++++---
> 2 files changed, 49 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
> index 79e90e338846..ae9d72f4d181 100644
> --- a/drivers/media/common/videobuf2/videobuf2-core.c
> +++ b/drivers/media/common/videobuf2/videobuf2-core.c
> @@ -2452,6 +2452,13 @@ int vb2_core_queue_init(struct vb2_queue *q)
> mutex_init(&q->mmap_lock);
> init_waitqueue_head(&q->done_wq);
>
> + q->max_num_bufs = 32;
> + q->bufs = kmalloc_array(q->max_num_bufs, sizeof(*q->bufs), GFP_KERNEL | __GFP_ZERO);
> + if (!q->bufs)
> + return -ENOMEM;
> +
> + spin_lock_init(&q->bufs_lock);
> +
> q->memory = VB2_MEMORY_UNKNOWN;
>
> if (q->buf_struct_size == 0)
> @@ -2479,6 +2486,7 @@ void vb2_core_queue_release(struct vb2_queue *q)
> mutex_lock(&q->mmap_lock);
> __vb2_queue_free(q, q->num_buffers);
> mutex_unlock(&q->mmap_lock);
> + kfree(q->bufs);
> }
> EXPORT_SYMBOL_GPL(vb2_core_queue_release);
>
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> index 5b1e3d801546..397dbf6e61e1 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -558,6 +558,8 @@ struct vb2_buf_ops {
> * @dma_dir: DMA mapping direction.
> * @bufs: videobuf2 buffer structures
> * @num_buffers: number of allocated/used buffers
> + * @bufs_lock: lock to protect bufs access
> + * @max_num_bufs: max number of buffers storable in bufs
> * @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 +621,10 @@ 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;
> + spinlock_t bufs_lock;
> + size_t max_num_bufs;
>
> struct list_head queued_list;
> unsigned int queued_count;
> @@ -1239,9 +1243,16 @@ 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 (index < q->num_buffers)
> - return q->bufs[index];
> - return NULL;
> + struct vb2_buffer *vb = NULL;
> +
> + spin_lock(&q->bufs_lock);
> +
> + if (index < q->max_num_bufs)
> + vb = q->bufs[index];
> +
> + spin_unlock(&q->bufs_lock);
> +
> + return vb;
> }
>
> /**
> @@ -1251,12 +1262,30 @@ static inline struct vb2_buffer *vb2_get_buffer(struct vb2_queue *q,
> */
> static inline bool vb2_queue_add_buffer(struct vb2_queue *q, struct vb2_buffer *vb)
> {
> - if (vb->index < VB2_MAX_FRAME) {
> + bool ret = false;
> +
> + spin_lock(&q->bufs_lock);
> +
> + if (vb->index >= q->max_num_bufs) {
> + struct vb2_buffer **tmp;
> +
> + tmp = krealloc_array(q->bufs, q->max_num_bufs * 2, sizeof(*q->bufs), GFP_KERNEL);
> + if (!tmp)
> + goto realloc_failed;
> +
> + q->max_num_bufs *= 2;
> + q->bufs = tmp;
> + }
> +
> + if (vb->index < q->max_num_bufs) {
> q->bufs[vb->index] = vb;
> - return true;
> + ret = true;
> }
>
> - return false;
> +realloc_failed:
> + spin_unlock(&q->bufs_lock);
> +
> + return ret;
> }
>
> /**
> @@ -1266,8 +1295,12 @@ static inline bool vb2_queue_add_buffer(struct vb2_queue *q, struct vb2_buffer *
> */
> static inline void vb2_queue_remove_buffer(struct vb2_queue *q, struct vb2_buffer *vb)
> {
> - if (vb->index < VB2_MAX_FRAME)
> + spin_lock(&q->bufs_lock);
> +
> + if (vb->index < q->max_num_bufs)
> q->bufs[vb->index] = NULL;
> +
> + spin_unlock(&q->bufs_lock);
> }
>
> /*
--
Regards,
Laurent Pinchart
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