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From: Daniel Vetter <daniel@ffwll.ch>
To: Weizhao Ouyang <o451686892@gmail.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>,
	Benjamin Gaignard <benjamin.gaignard@collabora.com>,
	Liam Mark <lmark@codeaurora.org>,
	Laura Abbott <labbott@kernel.org>,
	Brian Starkey <Brian.Starkey@arm.com>,
	John Stultz <john.stultz@linaro.org>,
	christian.koenig@amd.com, linaro-mm-sig@lists.linaro.org,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linux-media@vger.kernel.org
Subject: Re: [PATCH] dma-buf: cma_heap: Fix mutex locking section
Date: Wed, 19 Jan 2022 16:05:18 +0100	[thread overview]
Message-ID: <YegormDmEewox0MF@phenom.ffwll.local> (raw)
In-Reply-To: <20220104073545.124244-1-o451686892@gmail.com>

On Tue, Jan 04, 2022 at 03:35:45PM +0800, Weizhao Ouyang wrote:
> Fix cma_heap_buffer mutex locking critical section to protect vmap_cnt
> and vaddr.
> 
> Fixes: a5d2d29e24be ("dma-buf: heaps: Move heap-helper logic into the cma_heap implementation")
> Signed-off-by: Weizhao Ouyang <o451686892@gmail.com>
> ---
>  drivers/dma-buf/heaps/cma_heap.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c
> index 0c05b79870f9..83f02bd51dda 100644
> --- a/drivers/dma-buf/heaps/cma_heap.c
> +++ b/drivers/dma-buf/heaps/cma_heap.c
> @@ -124,10 +124,11 @@ static int cma_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
>  	struct cma_heap_buffer *buffer = dmabuf->priv;
>  	struct dma_heap_attachment *a;
>  
> +	mutex_lock(&buffer->lock);
> +
>  	if (buffer->vmap_cnt)
>  		invalidate_kernel_vmap_range(buffer->vaddr, buffer->len);

Since this creates nesting with mm/, but optionally I think it'd be good
to prime lockdep so it knows about this. See e.g. dma_resv_lockdep() in
dma-resv.c, except I don't know offhand what the right lock for
invalidate_kernel_vmap_range is.
-Daniel


>  
> -	mutex_lock(&buffer->lock);
>  	list_for_each_entry(a, &buffer->attachments, list) {
>  		if (!a->mapped)
>  			continue;
> @@ -144,10 +145,11 @@ static int cma_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf,
>  	struct cma_heap_buffer *buffer = dmabuf->priv;
>  	struct dma_heap_attachment *a;
>  
> +	mutex_lock(&buffer->lock);
> +
>  	if (buffer->vmap_cnt)
>  		flush_kernel_vmap_range(buffer->vaddr, buffer->len);
>  
> -	mutex_lock(&buffer->lock);
>  	list_for_each_entry(a, &buffer->attachments, list) {
>  		if (!a->mapped)
>  			continue;
> -- 
> 2.32.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

WARNING: multiple messages have this Message-ID (diff)
From: Daniel Vetter <daniel@ffwll.ch>
To: Weizhao Ouyang <o451686892@gmail.com>
Cc: Benjamin Gaignard <benjamin.gaignard@collabora.com>,
	christian.koenig@amd.com, dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org, Liam Mark <lmark@codeaurora.org>,
	linaro-mm-sig@lists.linaro.org, Laura Abbott <labbott@kernel.org>,
	linux-media@vger.kernel.org
Subject: Re: [PATCH] dma-buf: cma_heap: Fix mutex locking section
Date: Wed, 19 Jan 2022 16:05:18 +0100	[thread overview]
Message-ID: <YegormDmEewox0MF@phenom.ffwll.local> (raw)
In-Reply-To: <20220104073545.124244-1-o451686892@gmail.com>

On Tue, Jan 04, 2022 at 03:35:45PM +0800, Weizhao Ouyang wrote:
> Fix cma_heap_buffer mutex locking critical section to protect vmap_cnt
> and vaddr.
> 
> Fixes: a5d2d29e24be ("dma-buf: heaps: Move heap-helper logic into the cma_heap implementation")
> Signed-off-by: Weizhao Ouyang <o451686892@gmail.com>
> ---
>  drivers/dma-buf/heaps/cma_heap.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c
> index 0c05b79870f9..83f02bd51dda 100644
> --- a/drivers/dma-buf/heaps/cma_heap.c
> +++ b/drivers/dma-buf/heaps/cma_heap.c
> @@ -124,10 +124,11 @@ static int cma_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
>  	struct cma_heap_buffer *buffer = dmabuf->priv;
>  	struct dma_heap_attachment *a;
>  
> +	mutex_lock(&buffer->lock);
> +
>  	if (buffer->vmap_cnt)
>  		invalidate_kernel_vmap_range(buffer->vaddr, buffer->len);

Since this creates nesting with mm/, but optionally I think it'd be good
to prime lockdep so it knows about this. See e.g. dma_resv_lockdep() in
dma-resv.c, except I don't know offhand what the right lock for
invalidate_kernel_vmap_range is.
-Daniel


>  
> -	mutex_lock(&buffer->lock);
>  	list_for_each_entry(a, &buffer->attachments, list) {
>  		if (!a->mapped)
>  			continue;
> @@ -144,10 +145,11 @@ static int cma_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf,
>  	struct cma_heap_buffer *buffer = dmabuf->priv;
>  	struct dma_heap_attachment *a;
>  
> +	mutex_lock(&buffer->lock);
> +
>  	if (buffer->vmap_cnt)
>  		flush_kernel_vmap_range(buffer->vaddr, buffer->len);
>  
> -	mutex_lock(&buffer->lock);
>  	list_for_each_entry(a, &buffer->attachments, list) {
>  		if (!a->mapped)
>  			continue;
> -- 
> 2.32.0
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

  parent reply	other threads:[~2022-01-19 15:05 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-04  7:35 [PATCH] dma-buf: cma_heap: Fix mutex locking section Weizhao Ouyang
2022-01-04  7:35 ` Weizhao Ouyang
2022-01-04  7:42 ` John Stultz
2022-01-04  7:42   ` John Stultz
2022-01-13 11:07   ` Sumit Semwal
2022-01-13 11:07     ` Sumit Semwal
2022-01-19 15:05 ` Daniel Vetter [this message]
2022-01-19 15:05   ` Daniel Vetter

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