scsi: scsi_debug: Simplify request tag decoding

Since commit 64d513ac31bd ("scsi: use host wide tags by default") all
SCSI requests have a tag, whether or not scsi-mq is enabled.

Additionally, it is safe to use blk_mq_unique_tag() and
blk_mq_unique_tag_to_hwq() for legacy SCSI queues. Since this means that
the sdebug_mq_active variable is superfluous, remove it.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Douglas Gilbert <dgilbert@interlog.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index a5986da..7d2ce0c 100644 (file)
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -649,7 +649,6 @@ static bool sdebug_any_injecting_opt;
 static bool sdebug_verbose;
 static bool have_dif_prot;
 static bool sdebug_statistics = DEF_STATISTICS;
-static bool sdebug_mq_active;
 
 static unsigned int sdebug_store_sectors;
 static sector_t sdebug_capacity;       /* in sectors */
@@ -3727,20 +3726,13 @@ static int resp_xdwriteread_10(struct scsi_cmnd *scp,
 
 static struct sdebug_queue *get_queue(struct scsi_cmnd *cmnd)
 {
-       struct sdebug_queue *sqp = sdebug_q_arr;
+       u32 tag = blk_mq_unique_tag(cmnd->request);
+       u16 hwq = blk_mq_unique_tag_to_hwq(tag);
 
-       if (sdebug_mq_active) {
-               u32 tag = blk_mq_unique_tag(cmnd->request);
-               u16 hwq = blk_mq_unique_tag_to_hwq(tag);
-
-               if (unlikely(hwq >= submit_queues)) {
-                       pr_warn("Unexpected hwq=%d, apply modulo\n", hwq);
-                       hwq %= submit_queues;
-               }
-               pr_debug("tag=%u, hwq=%d\n", tag, hwq);
-               return sqp + hwq;
-       } else
-               return sqp;
+       pr_debug("tag=%#x, hwq=%d\n", tag, hwq);
+       if (WARN_ON_ONCE(hwq >= submit_queues))
+               hwq = 0;
+       return sdebug_q_arr + hwq;
 }
 
 /* Queued (deferred) command completions converge here. */
@@ -4587,9 +4579,8 @@ static int scsi_debug_show_info(struct seq_file *m, struct Scsi_Host *host)
                   num_host_resets);
        seq_printf(m, "dix_reads=%d, dix_writes=%d, dif_errors=%d\n",
                   dix_reads, dix_writes, dif_errors);
-       seq_printf(m, "usec_in_jiffy=%lu, %s=%d, mq_active=%d\n",
-                  TICK_NSEC / 1000, "statistics", sdebug_statistics,
-                  sdebug_mq_active);
+       seq_printf(m, "usec_in_jiffy=%lu, statistics=%d\n", TICK_NSEC / 1000,
+                  sdebug_statistics);
        seq_printf(m, "cmnd_count=%d, completions=%d, %s=%d, a_tsf=%d\n",
                   atomic_read(&sdebug_cmnd_count),
                   atomic_read(&sdebug_completions),
@@ -5612,13 +5603,8 @@ static int scsi_debug_queuecommand(struct Scsi_Host *shost,
                                n += scnprintf(b + n, sb - n, "%02x ",
                                               (u32)cmd[k]);
                }
-               if (sdebug_mq_active)
-                       sdev_printk(KERN_INFO, sdp, "%s: tag=%u, cmd %s\n",
-                                   my_name, blk_mq_unique_tag(scp->request),
-                                   b);
-               else
-                       sdev_printk(KERN_INFO, sdp, "%s: cmd %s\n", my_name,
-                                   b);
+               sdev_printk(KERN_INFO, sdp, "%s: tag=%#x, cmd %s\n", my_name,
+                           blk_mq_unique_tag(scp->request), b);
        }
        if (fake_host_busy(scp))
                return SCSI_MLQUEUE_HOST_BUSY;
@@ -5782,8 +5768,7 @@ static int sdebug_driver_probe(struct device * dev)
        }
        /* Decide whether to tell scsi subsystem that we want mq */
        /* Following should give the same answer for each host */
-       sdebug_mq_active = shost_use_blk_mq(hpnt) && (submit_queues > 1);
-       if (sdebug_mq_active)
+       if (shost_use_blk_mq(hpnt))
                hpnt->nr_hw_queues = submit_queues;
 
        sdbg_host->shost = hpnt;