CMT: [SRU][J/N:linux-bluefield][PATCH v2 1/1] mmc: core: Avoid bitfield RMW for claim/retune flags

[Masahiro Yamada]

On 3/12/26 23:01, Penghe Geng wrote:
> BugLink: https://bugs.launchpad.net/bugs/2143925
>
> (cherry picked from commit 901084c51a0a8fb42a3f37d2e9c62083c495f824)
>
> Move claimed and retune control flags out of the bitfield word to
> avoid unrelated RMW side effects in asynchronous contexts.
>
> The host->claimed bit shared a word with retune flags. Writes to claimed
> in __mmc_claim_host() or retune_now in mmc_mq_queue_rq() can overwrite
> other bits when concurrent updates happen in other contexts, triggering
> spurious WARN_ON(!host->claimed). Convert claimed, can_retune,
> retune_now and retune_paused to bool to remove shared-word coupling.
>
> Fixes: 6c0cedd1ef952 ("mmc: core: Introduce host claiming by context")
> Fixes: 1e8e55b67030c ("mmc: block: Add CQE support")
> Cc: stable at vger.kernel.org
> Suggested-by: Adrian Hunter <adrian.hunter at intel.com>
> Signed-off-by: Penghe Geng <pgeng at nvidia.com>
> Acked-by: Adrian Hunter <adrian.hunter at intel.com>
> Signed-off-by: Ulf Hansson <ulf.hansson at linaro.org>

The "cherry picked from" should be added here.

> Signed-off-by: Penghe Geng <pgeng at nvidia.com>
> ---
>   include/linux/mmc/host.h | 9 +++++----
>   1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> index a4ec7269b629..1f4ce6d9de1b 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -418,14 +418,12 @@ struct mmc_host {
>   
>   	struct mmc_ios		ios;		/* current io bus settings */
>   
> +	bool			claimed;	/* host exclusively claimed */
> +
>   	/* group bitfields together to minimize padding */
>   	unsigned int		use_spi_crc:1;
> -	unsigned int		claimed:1;	/* host exclusively claimed */
>   	unsigned int		doing_init_tune:1; /* initial tuning in progress */
> -	unsigned int		can_retune:1;	/* re-tuning can be used */
>   	unsigned int		doing_retune:1;	/* re-tuning in progress */
> -	unsigned int		retune_now:1;	/* do re-tuning at next req */
> -	unsigned int		retune_paused:1; /* re-tuning is temporarily disabled */
>   	unsigned int		retune_crc_disable:1; /* don't trigger retune upon crc */
>   	unsigned int		can_dma_map_merge:1; /* merging can be used */
>   	unsigned int		vqmmc_enabled:1; /* vqmmc regulator is enabled */
> @@ -433,6 +431,9 @@ struct mmc_host {
>   	int			rescan_disable;	/* disable card detection */
>   	int			rescan_entered;	/* used with nonremovable devices */
>   
> +	bool			can_retune;	/* re-tuning can be used */
> +	bool			retune_now;	/* do re-tuning at next req */
> +	bool			retune_paused;	/* re-tuning is temporarily disabled */
>   	int			need_retune;	/* re-tuning is needed */
>   	int			hold_retune;	/* hold off re-tuning */
>   	unsigned int		retune_period;	/* re-tuning period in secs */