scsi: scsi_debug: Stop using READ/WRITE_ONCE() when accessing sdebug_defer.defer_t

Using READ/WRITE_ONCE() means that the read or write is not torn by the
compiler.

READ/WRITE_ONCE() is always used when accessing sdebug_defer.defer_t.

However, we also guard the access in a spinlock when accessing that
member, and spinlock already guarantees no tearing, so stop using
READ/WRITE_ONCE().

Signed-off-by: John Garry <john.g.garry@oracle.com>
Link: https://patch.msgid.link/20251113133645.2898748-3-john.g.garry@oracle.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 19ebfb2b67e101c8940a53c8bad3497796116216..cbe15a76a98bd1024c313f177c52fc743d6d7be4 100644 (file)
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -6726,7 +6726,7 @@ static bool scsi_debug_stop_cmnd(struct scsi_cmnd *cmnd)
 {
        struct sdebug_scsi_cmd *sdsc = scsi_cmd_priv(cmnd);
        struct sdebug_defer *sd_dp = &sdsc->sd_dp;
-       enum sdeb_defer_type defer_t = READ_ONCE(sd_dp->defer_t);
+       enum sdeb_defer_type defer_t = sd_dp->defer_t;
 
        lockdep_assert_held(&sdsc->lock);
 
@@ -7288,12 +7288,12 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
                if (polled) {
                        spin_lock_irqsave(&sdsc->lock, flags);
                        sd_dp->cmpl_ts = ktime_add(ns_to_ktime(ns_from_boot), kt);
-                       WRITE_ONCE(sd_dp->defer_t, SDEB_DEFER_POLL);
+                       sd_dp->defer_t = SDEB_DEFER_POLL;
                        spin_unlock_irqrestore(&sdsc->lock, flags);
                } else {
                        /* schedule the invocation of scsi_done() for a later time */
                        spin_lock_irqsave(&sdsc->lock, flags);
-                       WRITE_ONCE(sd_dp->defer_t, SDEB_DEFER_HRT);
+                       sd_dp->defer_t = SDEB_DEFER_HRT;
                        hrtimer_start(&sd_dp->hrt, kt, HRTIMER_MODE_REL_PINNED);
                        /*
                         * The completion handler will try to grab sqcp->lock,
@@ -7317,11 +7317,11 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
                if (polled) {
                        spin_lock_irqsave(&sdsc->lock, flags);
                        sd_dp->cmpl_ts = ns_to_ktime(ns_from_boot);
-                       WRITE_ONCE(sd_dp->defer_t, SDEB_DEFER_POLL);
+                       sd_dp->defer_t = SDEB_DEFER_POLL;
                        spin_unlock_irqrestore(&sdsc->lock, flags);
                } else {
                        spin_lock_irqsave(&sdsc->lock, flags);
-                       WRITE_ONCE(sd_dp->defer_t, SDEB_DEFER_WQ);
+                       sd_dp->defer_t = SDEB_DEFER_WQ;
                        schedule_work(&sd_dp->ew.work);
                        spin_unlock_irqrestore(&sdsc->lock, flags);
                }
@@ -9125,7 +9125,7 @@ static bool sdebug_blk_mq_poll_iter(struct request *rq, void *opaque)
 
        spin_lock_irqsave(&sdsc->lock, flags);
        sd_dp = &sdsc->sd_dp;
-       if (READ_ONCE(sd_dp->defer_t) != SDEB_DEFER_POLL) {
+       if (sd_dp->defer_t != SDEB_DEFER_POLL) {
                spin_unlock_irqrestore(&sdsc->lock, flags);
                return true;
        }