linux-kernel - Re: [PATCH v2 2/2] i2c: lpi2c: Use cleanup helper for dma_async_tx

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Message-ID: <26b9cb6d-8370-4908-aed9-9c5b07e5fb82@intel.com>
Date: Wed, 3 Dec 2025 15:52:09 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: Frank Li <Frank.Li@....com>, Vinod Koul <vkoul@...nel.org>,
 Dong Aisheng <aisheng.dong@....com>, Andi Shyti <andi.shyti@...nel.org>,
 Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>,
 Pengutronix Kernel Team <kernel@...gutronix.de>,
 Fabio Estevam <festevam@...il.com>
Cc: dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-i2c@...r.kernel.org, imx@...ts.linux.dev,
 linux-arm-kernel@...ts.infradead.org, carlos.song@....com
Subject: Re: [PATCH v2 2/2] i2c: lpi2c: Use cleanup helper for
 dma_async_tx_descriptor error handling



On 10/3/25 9:26 AM, Frank Li wrote:
> Use the cleanup helper to simplify dma_async_tx_descriptor error handling.
> 
> No functional change.
> 
> Signed-off-by: Frank Li <Frank.Li@....com>
> ---
> change v2
>  need goto unmap buffer.
> 
> desc_prepare_err_exit:
>         dma_unmap_single(txchan->device->dev, dma->dma_tx_addr,
>                          dma->rx_cmd_buf_len, DMA_TO_DEVICE);
>         return -EINVAL;
> 
> submit_err_exit:
>         dma_unmap_single(txchan->device->dev, dma->dma_tx_addr,
>                          dma->rx_cmd_buf_len, DMA_TO_DEVICE);
>         dmaengine_desc_free(rx_cmd_desc)
> 
> auto cleanup by __free, so whole error path submit_err_exit can be removed
> and use desc_prepare_err_exit label.
> ---
>  drivers/i2c/busses/i2c-imx-lpi2c.c | 11 +++--------
>  1 file changed, 3 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-imx-lpi2c.c b/drivers/i2c/busses/i2c-imx-lpi2c.c
> index 03b5a7e8c361abe1d75fb4d31f9614bbc6387d93..e31c2d81f59f18a09d34f79896a7fa4bb83c0a12 100644
> --- a/drivers/i2c/busses/i2c-imx-lpi2c.c
> +++ b/drivers/i2c/busses/i2c-imx-lpi2c.c
> @@ -722,7 +722,7 @@ static void lpi2c_dma_callback(void *data)
>  
>  static int lpi2c_dma_rx_cmd_submit(struct lpi2c_imx_struct *lpi2c_imx)
>  {
> -	struct dma_async_tx_descriptor *rx_cmd_desc;
> +	struct dma_async_tx_descriptor *rx_cmd_desc __free(dma_async_tx_descriptor) = NULL;
>  	struct lpi2c_imx_dma *dma = lpi2c_imx->dma;
>  	struct dma_chan *txchan = dma->chan_tx;
>  	dma_cookie_t cookie;
> @@ -746,10 +746,11 @@ static int lpi2c_dma_rx_cmd_submit(struct lpi2c_imx_struct *lpi2c_imx)
>  	cookie = dmaengine_submit(rx_cmd_desc);
>  	if (dma_submit_error(cookie)) {
>  		dev_err(&lpi2c_imx->adapter.dev, "submitting DMA failed, use pio\n");
> -		goto submit_err_exit;
> +		goto desc_prepare_err_exit;

Typically if you are introducing cleanup usage, you will want to remove all the goto usages. Otherwise it gets kinda messy having both styles. Although not sure how to do a cleanup macro with dma_unmap_*. Unless a local one where lpi2c_imx_dma also contains a ptr to the device. Then that may be doable. 

DJ>  	}
>  
>  	dma_async_issue_pending(txchan);
> +	retain_and_null_ptr(rx_cmd_desc);
>  
>  	return 0;
>  
> @@ -757,12 +758,6 @@ static int lpi2c_dma_rx_cmd_submit(struct lpi2c_imx_struct *lpi2c_imx)
>  	dma_unmap_single(txchan->device->dev, dma->dma_tx_addr,
>  			 dma->rx_cmd_buf_len, DMA_TO_DEVICE);
>  	return -EINVAL;
> -
> -submit_err_exit:
> -	dma_unmap_single(txchan->device->dev, dma->dma_tx_addr,
> -			 dma->rx_cmd_buf_len, DMA_TO_DEVICE);
> -	dmaengine_desc_free(rx_cmd_desc);
> -	return -EINVAL;
>  }
>  
>  static int lpi2c_dma_submit(struct lpi2c_imx_struct *lpi2c_imx)
>