Re: [V2 PATCH 2/2] scsi: TUR path is down after adapter gets reset with multipath

[Hannes Reinecke <hare@suse.de>]

On 11/03/2014 10:18 PM, wenxiong@linux.vnet.ibm.com wrote:
> This patch fixes an issue with multipath ipr SAS devices which require a
> start unit command to be issued following an adapter reset. Without this
> patch, paths get marked failed following an adapter reset and since the
> error handler never gets invoked to issue the start unit, the paths are
> never recovered. Returning FAILED for this case ensures the error
> handler wakes up to issue the start unit.
> 
> Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
> Teste-by: Wen Xiong <wenxiong@linux.vnet.ibm.com>
> ---
>  drivers/scsi/device_handler/scsi_dh_alua.c |   20 +++++++++++++++++++-
>  1 file changed, 19 insertions(+), 1 deletion(-)
> 
> Index: b/drivers/scsi/device_handler/scsi_dh_alua.c
> ===================================================================
> --- a/drivers/scsi/device_handler/scsi_dh_alua.c	2014-10-29 20:50:29.000000000 -0500
> +++ b/drivers/scsi/device_handler/scsi_dh_alua.c	2014-11-03 14:24:39.482078993 -0600
> @@ -84,6 +84,7 @@ struct alua_dh_data {
>  
>  static char print_alua_state(int);
>  static int alua_check_sense(struct scsi_device *, struct scsi_sense_hdr *);
> +static int alua_check_sense_handler(struct scsi_device *, struct scsi_sense_hdr *);
>  
>  static inline struct alua_dh_data *get_alua_data(struct scsi_device *sdev)
>  {
> @@ -519,6 +520,23 @@ static int alua_check_sense(struct scsi_
>  	return SCSI_RETURN_NOT_HANDLED;
>  }
>  
> +static int alua_check_sense_handler(struct scsi_device *sdev,
> +			    struct scsi_sense_hdr *sense_hdr)
> +{
> +	switch (sense_hdr->sense_key) {
> +	case NOT_READY:
> +		if (sdev->allow_restart &&
> +		    sense_hdr->asc == 0x04 && sense_hdr->ascq == 0x02)
> +			/*
> +			 * if the device is not started, we need to wake
> +			 * the error handler to start the motor
> +			 */
> +			return FAILED;
> +		break;
> +	}
> +	alua_check_sense(sdev, sense_hdr);
> +}
> +
>  /*
>   * alua_rtpg - Evaluate REPORT TARGET GROUP STATES
>   * @sdev: the device to be evaluated.
> @@ -827,7 +845,7 @@ static struct scsi_device_handler alua_d
>  	.attach = alua_bus_attach,
>  	.detach = alua_bus_detach,
>  	.prep_fn = alua_prep_fn,
> -	.check_sense = alua_check_sense,
> +	.check_sense = alua_check_sense_handler,
>  	.activate = alua_activate,
>  	.set_params = alua_set_params,
>  	.match = alua_match,
> 
Why did you use a wrapper for an already existing function?
Please fold the logic into alua_check_sense().

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		      zSeries & Storage
hare@suse.de			      +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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