On Mon, 2019-09-23 at 11:31 +0530, Milan P. Gandhi wrote:
> Couple of users had requested to print the SCSI command age along 
> with command failure errors. This is a small change, but allows 
> users to get more important information about the command that was 
> failed, it would help the users in debugging the command failures:
> 
> Signed-off-by: Milan P. Gandhi <mgan...@redhat.com>
> ---
> diff --git a/drivers/scsi/scsi_logging.c
> b/drivers/scsi/scsi_logging.c
> index ecc5918e372a..ca2182bc53c6 100644
> --- a/drivers/scsi/scsi_logging.c
> +++ b/drivers/scsi/scsi_logging.c
> @@ -437,6 +437,7 @@ void scsi_print_result(const struct scsi_cmnd
> *cmd, const char *msg,
>       const char *mlret_string = scsi_mlreturn_string(disposition);
>       const char *hb_string = scsi_hostbyte_string(cmd->result);
>       const char *db_string = scsi_driverbyte_string(cmd->result);
> +     unsigned long cmd_age = (jiffies - cmd->jiffies_at_alloc) / HZ;
>  
>       logbuf = scsi_log_reserve_buffer(&logbuf_len);
>       if (!logbuf)
> @@ -478,10 +479,15 @@ void scsi_print_result(const struct scsi_cmnd
> *cmd, const char *msg,
>  
>       if (db_string)
>               off += scnprintf(logbuf + off, logbuf_len - off,
> -                              "driverbyte=%s", db_string);
> +                              "driverbyte=%s ", db_string);
>       else
>               off += scnprintf(logbuf + off, logbuf_len - off,
> -                              "driverbyte=0x%02x", driver_byte(cmd-
> >result));
> +                              "driverbyte=0x%02x ",
> +                              driver_byte(cmd->result));
> +
> +     off += scnprintf(logbuf + off, logbuf_len - off,
> +                      "cmd-age=%lus", cmd_age);
> +
>  out_printk:
>       dev_printk(KERN_INFO, &cmd->device->sdev_gendev, "%s", logbuf);
>       scsi_log_release_buffer(logbuf);
> 

This looks to be a useful debug addition to me, and the code looks
correct.
I believe this has also been tested by Milan in our lab.

Reviewed-by: Laurence Oberman <lober...@redhat.com> 

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