linux-kernel - Re: [PATCH v6 2/5] media: imx-jpeg: Reset slot data pointers when freed

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Message-ID: <aAaIJMZ3ZIy6+yVk@lizhi-Precision-Tower-5810>
Date: Mon, 21 Apr 2025 14:02:12 -0400
From: Frank Li <Frank.li@....com>
To: ming.qian@....nxp.com
Cc: mchehab@...nel.org, hverkuil-cisco@...all.nl,
	mirela.rabulea@....nxp.com, nicolas@...fresne.ca,
	shawnguo@...nel.org, s.hauer@...gutronix.de, kernel@...gutronix.de,
	festevam@...il.com, xiahong.bao@....com, eagle.zhou@....com,
	linux-imx@....com, imx@...ts.linux.dev, linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v6 2/5] media: imx-jpeg: Reset slot data pointers when
 freed

On Mon, Apr 21, 2025 at 04:12:53PM +0800, ming.qian@....nxp.com wrote:
> From: Ming Qian <ming.qian@....nxp.com>
>
> Ensure that the slot data pointers are reset to NULL and handles are
> set to 0 after freeing the coherent memory. This makes he function
> mxc_jpeg_alloc_slot_data() and mxc_jpeg_free_slot_data() safe to be
> called multiple times.
>
> Fixes: 2db16c6ed72c ("media: imx-jpeg: Add V4L2 driver for i.MX8 JPEG Encoder/Decoder")
> Signed-off-by: Ming Qian <ming.qian@....nxp.com>
> Reviewed-by: Nicolas Dufresne <nicolas.dufresne@...labora.com>

Reviewed-by: Frank Li <Frank.Li@....com>

> ---
> v6
> - Improve commit message
>
> v5
> - Split the resetting pointer when freed to a separate patch
> ---
>  drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c b/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
> index ad2284e87985..29d3d4b08dd1 100644
> --- a/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
> +++ b/drivers/media/platform/nxp/imx-jpeg/mxc-jpeg.c
> @@ -758,16 +758,22 @@ static void mxc_jpeg_free_slot_data(struct mxc_jpeg_dev *jpeg)
>  	dma_free_coherent(jpeg->dev, sizeof(struct mxc_jpeg_desc),
>  			  jpeg->slot_data.desc,
>  			  jpeg->slot_data.desc_handle);
> +	jpeg->slot_data.desc = NULL;
> +	jpeg->slot_data.desc_handle = 0;
>
>  	/* free descriptor for encoder configuration phase / decoder DHT */
>  	dma_free_coherent(jpeg->dev, sizeof(struct mxc_jpeg_desc),
>  			  jpeg->slot_data.cfg_desc,
>  			  jpeg->slot_data.cfg_desc_handle);
> +	jpeg->slot_data.cfg_desc_handle = 0;
> +	jpeg->slot_data.cfg_desc = NULL;
>
>  	/* free configuration stream */
>  	dma_free_coherent(jpeg->dev, MXC_JPEG_MAX_CFG_STREAM,
>  			  jpeg->slot_data.cfg_stream_vaddr,
>  			  jpeg->slot_data.cfg_stream_handle);
> +	jpeg->slot_data.cfg_stream_vaddr = NULL;
> +	jpeg->slot_data.cfg_stream_handle = 0;
>
>  	jpeg->slot_data.used = false;
>  }
> --
> 2.43.0-rc1
>