Re: [PATCH 17/18] scsi: Add scsi_vpd_tpg_id()

[Johannes Thumshirn <jthumshirn@suse.com>]

On Mon, 2015-11-09 at 16:08 +0100, Hannes Reinecke wrote:
> Implement scsi_vpd_tpg_id() to extract the target
> port group id and the relative port id from
> SCSI VPD page 0x83.
> 
> Signed-off-by: Hannes Reinecke <hare@suse.de>
> ---
>  drivers/scsi/scsi_lib.c    | 48
> ++++++++++++++++++++++++++++++++++++++++++++++
>  include/scsi/scsi_device.h |  1 +
>  2 files changed, 49 insertions(+)
> 
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
> index 3cb295c..d12edc8 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -23,6 +23,7 @@
>  #include <linux/scatterlist.h>
>  #include <linux/blk-mq.h>
>  #include <linux/ratelimit.h>
> +#include <asm/unaligned.h>
>  
>  #include <scsi/scsi.h>
>  #include <scsi/scsi_cmnd.h>
> @@ -3294,3 +3295,50 @@ next_desig:
>  	return id_size;
>  }
>  EXPORT_SYMBOL(scsi_vpd_lun_id);
> +
> +/*
> + * scsi_vpd_tpg_id - return a target port group identifier
> + * @sdev: SCSI device
> + *
> + * Returns the Target Port Group identifier from the information
> + * froom VPD page 0x83 of the device.
> + *
> + * Returns the identifier or error on failure.
> + */
> +int scsi_vpd_tpg_id(struct scsi_device *sdev, int *rel_id)
> +{
> +	unsigned char *d;
> +	unsigned char __rcu *vpd_pg83;
> +	int group_id = -EAGAIN, rel_port = -1;
> +
> +	rcu_read_lock();
> +	vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
> +	if (!vpd_pg83) {
> +		rcu_read_unlock();
> +		return -ENXIO;
> +	}
> +
> +	d = sdev->vpd_pg83 + 4;
> +	while (d < sdev->vpd_pg83 + sdev->vpd_pg83_len) {
> +		switch (d[1] & 0xf) {
> +		case 0x4:
> +			/* Relative target port */
> +			rel_port = get_unaligned_be16(&d[6]);
> +			break;
> +		case 0x5:
> +			/* Target port group */
> +			group_id = get_unaligned_be16(&d[6]);
> +			break;
> +		default:
> +			break;
> +		}
> +		d += d[3] + 4;
> +	}
> +	rcu_read_unlock();
> +
> +	if (group_id >= 0 && rel_id && rel_port != -1)
> +		*rel_id = rel_port;
> +
> +	return group_id;
> +}
> +EXPORT_SYMBOL(scsi_vpd_tpg_id);
> diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
> index 4c49cfa..f63a167 100644
> --- a/include/scsi/scsi_device.h
> +++ b/include/scsi/scsi_device.h
> @@ -416,6 +416,7 @@ static inline int scsi_execute_req(struct
> scsi_device *sdev,
>  extern void sdev_disable_disk_events(struct scsi_device *sdev);
>  extern void sdev_enable_disk_events(struct scsi_device *sdev);
>  extern int scsi_vpd_lun_id(struct scsi_device *, char *, size_t);
> +extern int scsi_vpd_tpg_id(struct scsi_device *, int *);
>  
>  #ifdef CONFIG_PM
>  extern int scsi_autopm_get_device(struct scsi_device *);

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>

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