scsi: scsi_debug: Strengthen defer_t accesses

Use READ_ONCE() and WRITE_ONCE() macros when accessing the
sdebug_defer::defer_t value.

Link: https://lore.kernel.org/r/20220109012853.301953-3-dgilbert@interlog.com
Signed-off-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 24f3905..40f698e 100644 (file)
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -4782,7 +4782,7 @@ static void sdebug_q_cmd_complete(struct sdebug_defer *sd_dp)
                return;
        }
        spin_lock_irqsave(&sqp->qc_lock, iflags);
-       sd_dp->defer_t = SDEB_DEFER_NONE;
+       WRITE_ONCE(sd_dp->defer_t, SDEB_DEFER_NONE);
        sqcp = &sqp->qc_arr[qc_idx];
        scp = sqcp->a_cmnd;
        if (unlikely(scp == NULL)) {
@@ -5103,8 +5103,8 @@ static bool stop_queued_cmnd(struct scsi_cmnd *cmnd)
                                sqcp->a_cmnd = NULL;
                                sd_dp = sqcp->sd_dp;
                                if (sd_dp) {
-                                       l_defer_t = sd_dp->defer_t;
-                                       sd_dp->defer_t = SDEB_DEFER_NONE;
+                                       l_defer_t = READ_ONCE(sd_dp->defer_t);
+                                       WRITE_ONCE(sd_dp->defer_t, SDEB_DEFER_NONE);
                                } else
                                        l_defer_t = SDEB_DEFER_NONE;
                                spin_unlock_irqrestore(&sqp->qc_lock, iflags);
@@ -5145,8 +5145,8 @@ static void stop_all_queued(bool done_with_no_conn)
                                sqcp->a_cmnd = NULL;
                                sd_dp = sqcp->sd_dp;
                                if (sd_dp) {
-                                       l_defer_t = sd_dp->defer_t;
-                                       sd_dp->defer_t = SDEB_DEFER_NONE;
+                                       l_defer_t = READ_ONCE(sd_dp->defer_t);
+                                       WRITE_ONCE(sd_dp->defer_t, SDEB_DEFER_NONE);
                                } else
                                        l_defer_t = SDEB_DEFER_NONE;
                                spin_unlock_irqrestore(&sqp->qc_lock, iflags);
@@ -5627,7 +5627,7 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
                                sd_dp->sqa_idx = sqp - sdebug_q_arr;
                                sd_dp->qc_idx = k;
                        }
-                       sd_dp->defer_t = SDEB_DEFER_POLL;
+                       WRITE_ONCE(sd_dp->defer_t, SDEB_DEFER_POLL);
                        spin_unlock_irqrestore(&sqp->qc_lock, iflags);
                } else {
                        if (!sd_dp->init_hrt) {
@@ -5639,7 +5639,7 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
                                sd_dp->sqa_idx = sqp - sdebug_q_arr;
                                sd_dp->qc_idx = k;
                        }
-                       sd_dp->defer_t = SDEB_DEFER_HRT;
+                       WRITE_ONCE(sd_dp->defer_t, SDEB_DEFER_HRT);
                        /* schedule the invocation of scsi_done() for a later time */
                        hrtimer_start(&sd_dp->hrt, kt, HRTIMER_MODE_REL_PINNED);
                }
@@ -5658,7 +5658,7 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
                                sd_dp->sqa_idx = sqp - sdebug_q_arr;
                                sd_dp->qc_idx = k;
                        }
-                       sd_dp->defer_t = SDEB_DEFER_POLL;
+                       WRITE_ONCE(sd_dp->defer_t, SDEB_DEFER_POLL);
                        spin_unlock_irqrestore(&sqp->qc_lock, iflags);
                } else {
                        if (!sd_dp->init_wq) {
@@ -5668,7 +5668,7 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
                                sd_dp->qc_idx = k;
                                INIT_WORK(&sd_dp->ew.work, sdebug_q_cmd_wq_complete);
                        }
-                       sd_dp->defer_t = SDEB_DEFER_WQ;
+                       WRITE_ONCE(sd_dp->defer_t, SDEB_DEFER_WQ);
                        schedule_work(&sd_dp->ew.work);
                }
                if (sdebug_statistics)
@@ -7436,7 +7436,7 @@ static int sdebug_blk_mq_poll(struct Scsi_Host *shost, unsigned int queue_num)
                               queue_num, qc_idx, __func__);
                        break;
                }
-               if (sd_dp->defer_t == SDEB_DEFER_POLL) {
+               if (READ_ONCE(sd_dp->defer_t) == SDEB_DEFER_POLL) {
                        if (kt_from_boot < sd_dp->cmpl_ts)
                                continue;
 
@@ -7470,7 +7470,7 @@ static int sdebug_blk_mq_poll(struct Scsi_Host *shost, unsigned int queue_num)
                        else
                                atomic_set(&retired_max_queue, k + 1);
                }
-               sd_dp->defer_t = SDEB_DEFER_NONE;
+               WRITE_ONCE(sd_dp->defer_t, SDEB_DEFER_NONE);
                spin_unlock_irqrestore(&sqp->qc_lock, iflags);
                scsi_done(scp); /* callback to mid level */
                spin_lock_irqsave(&sqp->qc_lock, iflags);