[PATCH 0/2] dmaengine: Add cleanup to simple code

[PATCH 0/2] dmaengine: Add cleanup to simple code

[Frank Li]

start_dma()
{
        struct dma_async_tx_descriptor *rx_cmd_desc __free(dma_async_tx_descriptor) = NULL;
        ...
        cookie = dmaengine_submit(rx_cmd_desc);
        if (dma_submit_error(cookie))
                return dma_submit_error(cookie);
        ...
        retain_and_null_ptr(rx_cmd_desc);

        return 0;
}

To: Vinod Koul <vkoul@kernel.org>
To: Dong Aisheng <aisheng.dong@nxp.com>
To: Andi Shyti <andi.shyti@kernel.org>
To: Shawn Guo <shawnguo@kernel.org>
To: Sascha Hauer <s.hauer@pengutronix.de>
To: Pengutronix Kernel Team <kernel@pengutronix.de>
To: Fabio Estevam <festevam@gmail.com>
Cc: dmaengine@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-i2c@vger.kernel.org
Cc: imx@lists.linux.dev
Cc: linux-arm-kernel@lists.infradead.org
Cc: carlos.song@nxp.com

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
Frank Li (2):
      dmaengine: Add cleanup FREE defines for dma_async_tx_descriptor
      i2c: lpi2c: Use cleanup helper for dma_async_tx_descriptor error handling

 drivers/i2c/busses/i2c-imx-lpi2c.c | 11 +++--------
 include/linux/dmaengine.h          |  4 +++-
 2 files changed, 6 insertions(+), 9 deletions(-)
---
base-commit: 019ffdd87705bcef1ca5cf9bfdd2b358ce190ab5
change-id: 20251001-dma_chan_free-0392f4004d9e

Best regards,
--
Frank Li <Frank.Li@nxp.com>

[PATCH 1/2] dmaengine: Add cleanup FREE defines for dma_async_tx_descriptor

[Frank Li]

Add cleanup FREE defines for dma_async_tx_descriptor to support automatic
cleanup and simplify error handling.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
Check patch report exceed 100 chars, but it's still better put into one
line to keep consistent with other DEFINE_FREE and better readablity
---
 include/linux/dmaengine.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 99efe2b9b4ea9844ca6161208362ef18ef111d96..7826b40727ab889c9167343bf15628b83b85647c 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -5,6 +5,7 @@
 #ifndef LINUX_DMAENGINE_H
 #define LINUX_DMAENGINE_H
 
+#include <linux/cleanup.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/uio.h>
@@ -1525,7 +1526,6 @@ struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
 struct dma_chan *dma_request_chan(struct device *dev, const char *name);
 struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask);
 struct dma_chan *devm_dma_request_chan(struct device *dev, const char *name);
-
 void dma_release_channel(struct dma_chan *chan);
 int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps);
 #else
@@ -1612,6 +1612,8 @@ static inline int dmaengine_desc_free(struct dma_async_tx_descriptor *desc)
 	return desc->desc_free(desc);
 }
 
+DEFINE_FREE(dma_async_tx_descriptor, struct dma_async_tx_descriptor *, if (_T) dmaengine_desc_free(_T))
+
 /* --- DMA device --- */
 
 int dma_async_device_register(struct dma_device *device);

-- 
2.34.1

[PATCH 2/2] i2c: lpi2c: Use cleanup helper for dma_async_tx_descriptor error handling

[Frank Li]

Use the cleanup helper to simplify dma_async_tx_descriptor error handling.

No functional change.

Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
 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..b1d035ca8002e9648b67bfe4d674578373394710 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;
+		return dma_submit_error(cookie);
 	}
 
 	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)

-- 
2.34.1

Re: [PATCH 2/2] i2c: lpi2c: Use cleanup helper for dma_async_tx_descriptor error handling

[Christophe JAILLET]

Le 02/10/2025 à 21:49, Frank Li a écrit :
> Use the cleanup helper to simplify dma_async_tx_descriptor error handling.
> 
> No functional change.
> 
> Signed-off-by: Frank Li <Frank.Li@nxp.com>
> ---
>   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..b1d035ca8002e9648b67bfe4d674578373394710 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;
> +		return dma_submit_error(cookie);

I don't know if it matters or not, but this may change the returned 
value in this error handling path.

>   	}
>   
>   	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);

dma_unmap_single() is not needed anymore?

> -	dmaengine_desc_free(rx_cmd_desc);
> -	return -EINVAL;
>   }
>   
>   static int lpi2c_dma_submit(struct lpi2c_imx_struct *lpi2c_imx)
> 

Re: [PATCH 2/2] i2c: lpi2c: Use cleanup helper for dma_async_tx_descriptor error handling

[Frank Li]

On Thu, Oct 02, 2025 at 10:10:16PM +0200, Christophe JAILLET wrote:
> Le 02/10/2025 à 21:49, Frank Li a écrit :
> > Use the cleanup helper to simplify dma_async_tx_descriptor error handling.
> >
> > No functional change.
> >
> > Signed-off-by: Frank Li <Frank.Li@nxp.com>
> > ---
> >   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..b1d035ca8002e9648b67bfe4d674578373394710 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;
> > +		return dma_submit_error(cookie);
>
> I don't know if it matters or not, but this may change the returned value in
> this error handling path.
>
> >   	}
> >   	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);
>
> dma_unmap_single() is not needed anymore?

Previous label position should be before submit_err_exit to avoid
duplicate dma_unmap_single() twice at error path. After remove
submit_err_exit, needn't dma_unmap_single() here.

But previous return dma_submit_error(cookie) is wrong, should be
goto desc_prepare_err_exit;

Frank
>
> > -	dmaengine_desc_free(rx_cmd_desc);
> > -	return -EINVAL;
> >   }
> >   static int lpi2c_dma_submit(struct lpi2c_imx_struct *lpi2c_imx)
> >
>