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Subject: [GIT PULL] SCSI fixes for 5.14-rc7
From:   James Bottomley <James.Bottomley@HansenPartnership.com>
To:     Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>
Cc:     linux-scsi <linux-scsi@vger.kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
Date:   Sat, 28 Aug 2021 11:09:55 -0700
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A single fix for a race introduced by a fix that went up in 5.14-rc5.

The patch is available here:

git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi.git scsi-fixes

The short changelog is:

Li Jinlin (1):
      scsi: core: Fix hang of freezing queue between blocking and running device

And the diffstat:

 drivers/scsi/scsi_sysfs.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

With full diff below.

James

---

diff --git a/drivers/scsi/scsi_sysfs.c b/drivers/scsi/scsi_sysfs.c
index ae9bfc658203..c0d31119d6d7 100644
--- a/drivers/scsi/scsi_sysfs.c
+++ b/drivers/scsi/scsi_sysfs.c
@@ -808,12 +808,15 @@ store_state_field(struct device *dev, struct device_attribute *attr,
 	ret = scsi_device_set_state(sdev, state);
 	/*
 	 * If the device state changes to SDEV_RUNNING, we need to
-	 * rescan the device to revalidate it, and run the queue to
-	 * avoid I/O hang.
+	 * run the queue to avoid I/O hang, and rescan the device
+	 * to revalidate it. Running the queue first is necessary
+	 * because another thread may be waiting inside
+	 * blk_mq_freeze_queue_wait() and because that call may be
+	 * waiting for pending I/O to finish.
 	 */
 	if (ret == 0 && state == SDEV_RUNNING) {
-		scsi_rescan_device(dev);
 		blk_mq_run_hw_queues(sdev->request_queue, true);
+		scsi_rescan_device(dev);
 	}
 	mutex_unlock(&sdev->state_mutex);