Re: [PATCH v3] mtd: spi-nor: use guard() in spi_nor_rww_start_exclusive

[Tudor Ambarus <tudor.ambarus@linaro.org>]

On 8/11/26 11:31 AM, Runyu Xiao wrote:
> Commit 03e7bb864d9a ("mtd: spi-nor: use scope-based mutex cleanup
> helpers") converted the RWW start helpers to scoped mutex cleanup, but
> left spi_nor_rww_start_exclusive() using a plain mutex_lock().
> 
> spi_nor_rww_start_exclusive() is used as a wait_event_killable()
> condition. When it returns false on the busy path, the raw mutex_lock()
> leaves nor->lock held and blocks the operation that must clear the RWW
> state in spi_nor_rww_end_exclusive().
> 
> Use guard(mutex) here as well so this helper matches the other RWW
> start helpers and releases nor->lock on the false return path.
> 
> Fixes: 03e7bb864d9a ("mtd: spi-nor: use scope-based mutex cleanup helpers")
> Cc: stable@vger.kernel.org
> Signed-off-by: Runyu Xiao <runyu.xiao@seu.edu.cn>

Reviewed-by: Tudor Ambarus <tudor.ambarus@linaro.org>

> ---
> Changes in v3:
> - Reframe the changelog around the scoped-helper conversion that missed
>   spi_nor_rww_start_exclusive().
> 
> Changes in v2:
> - Replace the analysis-style explanation with a short maintainer-facing
>   description of the busy-path lock hold.
> - Keep the fix focused on using guard(mutex) so the mutex is released on
>   both paths.
> 
> drivers/mtd/spi-nor/core.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> index ccf4396cdcd0..8bc117b46e02 100644
> --- a/drivers/mtd/spi-nor/core.c
> +++ b/drivers/mtd/spi-nor/core.c
> @@ -1310,7 +1310,7 @@ static bool spi_nor_rww_start_exclusive(struct spi_nor *nor)
>  {
>  	struct spi_nor_rww *rww = &nor->rww;
>  
> -	mutex_lock(&nor->lock);
> +	guard(mutex)(&nor->lock);
>  
>  	if (rww->ongoing_io || rww->ongoing_rd || rww->ongoing_pe)
>  		return false;


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