Re: [PATCH v3 1/1] scsi: scsi_dh_alua: increase default ALUA timeout to maximum spec value

[Hannes Reinecke <hare@suse.de>]

On 4/14/26 20:27, Brian Bunker wrote:
> The ALUA handler maps a 0 value (no implicit transition timeout provided
> by the target) to the ALUA_FAILOVER_TIMEOUT constant, currently 60
> seconds. This means the kernel already does not accept an infinite
> transition time.
> 
> However, 60 seconds is insufficient for some arrays that may take
> longer to complete ALUA transitions. Since the highest value allowed
> by the SCSI specification for the implicit transition timeout is a
> single byte (255 seconds), change the default to U8_MAX. This way,
> when a target does not provide an explicit transition timeout, we
> default to the maximum value the spec allows rather than an arbitrary
> 60 second limit.
> 
> Signed-off-by: Krishna Kant <krishna.kant@purestorage.com>
> Signed-off-by: Riya Savla <rsavla@purestorage.com>
> Signed-off-by: Brian Bunker <brian@purestorage.com>
> ---
>   drivers/scsi/device_handler/scsi_dh_alua.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
> index efb08b9b145a1..8ef1eecf9f9c3 100644
> --- a/drivers/scsi/device_handler/scsi_dh_alua.c
> +++ b/drivers/scsi/device_handler/scsi_dh_alua.c
> @@ -37,7 +37,7 @@
>   #define TPGS_MODE_EXPLICIT		0x2
>   
>   #define ALUA_RTPG_SIZE			128
> -#define ALUA_FAILOVER_TIMEOUT		60
> +#define ALUA_FAILOVER_TIMEOUT		U8_MAX
>   #define ALUA_FAILOVER_RETRIES		5
>   #define ALUA_RTPG_DELAY_MSECS		5
>   #define ALUA_RTPG_RETRY_DELAY		2

I'd rather use the numerical value (ie 255), and add a comment that
the timeout is an 8-bit value to deter people from raising it
further.

Otherwise looks good.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@suse.de                                +49 911 74053 688
SUSE Software Solutions GmbH, Frankenstr. 146, 90461 Nürnberg
HRB 36809 (AG Nürnberg), GF: I. Totev, A. McDonald, W. Knoblich