linux-kernel - Re: [PATCH v2] dma-buf/sw_sync: Decrement refcount on error in sw_sync_ioctl_get

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Message-ID: <f30552b0-36a7-4a56-a117-44e9eb3a14bf@amd.com>
Date: Fri, 11 Apr 2025 15:20:06 +0200
From: Christian König <christian.koenig@....com>
To: Dan Carpenter <dan.carpenter@...aro.org>,
 Rob Clark <robdclark@...omium.org>
Cc: Sumit Semwal <sumit.semwal@...aro.org>,
 Gustavo Padovan <gustavo@...ovan.org>, Dmitry Baryshkov <lumag@...nel.org>,
 Pekka Paalanen <pekka.paalanen@...labora.com>, linux-media@...r.kernel.org,
 dri-devel@...ts.freedesktop.org, linaro-mm-sig@...ts.linaro.org,
 linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH v2] dma-buf/sw_sync: Decrement refcount on error in
 sw_sync_ioctl_get_deadline()

Am 08.04.25 um 13:01 schrieb Dan Carpenter:
> Call dma_fence_put(fence) before returning an error if
> dma_fence_to_sync_pt() fails.  Use an unwind ladder at the
> end of the function to do the cleanup.
>
> Fixes: 70e67aaec2f4 ("dma-buf/sw_sync: Add fence deadline support")
> Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>

Reviewed and pushed to drm-misc-fixes.

Sorry for the delay, I was fighting a bit with dim after the migration.

Thanks,
Christian.

> ---
> v2: style changes.
>
>  drivers/dma-buf/sw_sync.c | 19 ++++++++++++++-----
>  1 file changed, 14 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/dma-buf/sw_sync.c b/drivers/dma-buf/sw_sync.c
> index f5905d67dedb..22a808995f10 100644
> --- a/drivers/dma-buf/sw_sync.c
> +++ b/drivers/dma-buf/sw_sync.c
> @@ -438,15 +438,17 @@ static int sw_sync_ioctl_get_deadline(struct sync_timeline *obj, unsigned long a
>  		return -EINVAL;
>  
>  	pt = dma_fence_to_sync_pt(fence);
> -	if (!pt)
> -		return -EINVAL;
> +	if (!pt) {
> +		ret = -EINVAL;
> +		goto put_fence;
> +	}
>  
>  	spin_lock_irqsave(fence->lock, flags);
> -	if (test_bit(SW_SYNC_HAS_DEADLINE_BIT, &fence->flags)) {
> -		data.deadline_ns = ktime_to_ns(pt->deadline);
> -	} else {
> +	if (!test_bit(SW_SYNC_HAS_DEADLINE_BIT, &fence->flags)) {
>  		ret = -ENOENT;
> +		goto unlock;
>  	}
> +	data.deadline_ns = ktime_to_ns(pt->deadline);
>  	spin_unlock_irqrestore(fence->lock, flags);
>  
>  	dma_fence_put(fence);
> @@ -458,6 +460,13 @@ static int sw_sync_ioctl_get_deadline(struct sync_timeline *obj, unsigned long a
>  		return -EFAULT;
>  
>  	return 0;
> +
> +unlock:
> +	spin_unlock_irqrestore(fence->lock, flags);
> +put_fence:
> +	dma_fence_put(fence);
> +
> +	return ret;
>  }
>  
>  static long sw_sync_ioctl(struct file *file, unsigned int cmd,