[PATCH] mtd: rawnand: lpc32xx_slc: fail DMA transfer on completion timeout

[PATCH] mtd: rawnand: lpc32xx_slc: fail DMA transfer on completion timeout

[Pengpeng Hou]

lpc32xx_xmit_dma() waits for the DMA completion callback but ignores
wait_for_completion_timeout(). A timed out DMA transfer is therefore
unmapped and reported as successful to the NAND read/write path.

Return -ETIMEDOUT when the completion wait expires. Terminate the DMA
channel before unmapping the scatterlist so the timed out transfer cannot
continue to access the buffer after the error is returned.

Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
---
 drivers/mtd/nand/raw/lpc32xx_slc.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/raw/lpc32xx_slc.c b/drivers/mtd/nand/raw/lpc32xx_slc.c
index 3ca30e7dc..10c808020 100644
--- a/drivers/mtd/nand/raw/lpc32xx_slc.c
+++ b/drivers/mtd/nand/raw/lpc32xx_slc.c
@@ -430,6 +430,7 @@ static int lpc32xx_xmit_dma(struct mtd_info *mtd, dma_addr_t dma,
 	struct dma_async_tx_descriptor *desc;
 	int flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
 	int res;
+	unsigned long time_left;
 
 	host->dma_slave_config.direction = dir;
 	host->dma_slave_config.src_addr = dma;
@@ -467,12 +468,19 @@ static int lpc32xx_xmit_dma(struct mtd_info *mtd, dma_addr_t dma,
 	dmaengine_submit(desc);
 	dma_async_issue_pending(host->dma_chan);
 
-	wait_for_completion_timeout(&host->comp, msecs_to_jiffies(1000));
+	time_left = wait_for_completion_timeout(&host->comp,
+						msecs_to_jiffies(1000));
+	if (!time_left) {
+		dmaengine_terminate_sync(host->dma_chan);
+		res = -ETIMEDOUT;
+	} else {
+		res = 0;
+	}
 
 	dma_unmap_sg(host->dma_chan->device->dev, &host->sgl, 1,
 		     DMA_BIDIRECTIONAL);
 
-	return 0;
+	return res;
 out1:
 	dma_unmap_sg(host->dma_chan->device->dev, &host->sgl, 1,
 		     DMA_BIDIRECTIONAL);
-- 
2.50.1 (Apple Git-155)


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Re: [PATCH] mtd: rawnand: lpc32xx_slc: fail DMA transfer on completion timeout

[Vladimir Zapolskiy]

On 6/24/26 17:41, Pengpeng Hou wrote:
> lpc32xx_xmit_dma() waits for the DMA completion callback but ignores
> wait_for_completion_timeout(). A timed out DMA transfer is therefore
> unmapped and reported as successful to the NAND read/write path.
> 
> Return -ETIMEDOUT when the completion wait expires. Terminate the DMA
> channel before unmapping the scatterlist so the timed out transfer cannot
> continue to access the buffer after the error is returned.
> 
> Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
> ---
>   drivers/mtd/nand/raw/lpc32xx_slc.c | 12 ++++++++++--
>   1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/lpc32xx_slc.c b/drivers/mtd/nand/raw/lpc32xx_slc.c
> index 3ca30e7dc..10c808020 100644
> --- a/drivers/mtd/nand/raw/lpc32xx_slc.c
> +++ b/drivers/mtd/nand/raw/lpc32xx_slc.c
> @@ -430,6 +430,7 @@ static int lpc32xx_xmit_dma(struct mtd_info *mtd, dma_addr_t dma,
>   	struct dma_async_tx_descriptor *desc;
>   	int flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
>   	int res;
> +	unsigned long time_left;
>   
>   	host->dma_slave_config.direction = dir;
>   	host->dma_slave_config.src_addr = dma;
> @@ -467,12 +468,19 @@ static int lpc32xx_xmit_dma(struct mtd_info *mtd, dma_addr_t dma,
>   	dmaengine_submit(desc);
>   	dma_async_issue_pending(host->dma_chan);
>   
> -	wait_for_completion_timeout(&host->comp, msecs_to_jiffies(1000));
> +	time_left = wait_for_completion_timeout(&host->comp,
> +						msecs_to_jiffies(1000));
> +	if (!time_left) {
> +		dmaengine_terminate_sync(host->dma_chan);
> +		res = -ETIMEDOUT;
> +	} else {
> +		res = 0;
> +	}
>   
>   	dma_unmap_sg(host->dma_chan->device->dev, &host->sgl, 1,
>   		     DMA_BIDIRECTIONAL);
>   
> -	return 0;
> +	return res;
>   out1:
>   	dma_unmap_sg(host->dma_chan->device->dev, &host->sgl, 1,
>   		     DMA_BIDIRECTIONAL);

Thank you for the change.

Reviewed-by: Vladimir Zapolskiy <vz@kernel.org>

-- 
Best wishes,
Vladimir

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