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[v2,2/2] scsi: scsi_debug: fix qc_lock use in sdebug_blk_mq_poll()

Message ID 20220301113009.595857-3-damien.lemoal@opensource.wdc.com (mailing list archive)
State Accepted
Headers show
Series Fix sparse warnings in scsi_debug | expand

Commit Message

Damien Le Moal March 1, 2022, 11:30 a.m. UTC
The use of the locked boolean variable to control locking and unlocking
of the qc_lock spinlock of struct sdebug_queue confuses sparse, leading
to a warning about an unexpected unlock. Simplify the qc_lock lock/unlock
handling code of this function to avoid this warning by removing the
locked boolean variable. This change also fixes unlocked access to
the in_use_bm bitmap with the find_first_bit() function.

Fixes: b05d4e481eff ("scsi: scsi_debug: Refine sdebug_blk_mq_poll()")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
---
 drivers/scsi/scsi_debug.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)
diff mbox series

Patch

diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
index f4e97f2224b2..25fa8e93f5a8 100644
--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -7509,7 +7509,6 @@  static int sdebug_blk_mq_poll(struct Scsi_Host *shost, unsigned int queue_num)
 {
 	bool first;
 	bool retiring = false;
-	bool locked = false;
 	int num_entries = 0;
 	unsigned int qc_idx = 0;
 	unsigned long iflags;
@@ -7525,11 +7524,9 @@  static int sdebug_blk_mq_poll(struct Scsi_Host *shost, unsigned int queue_num)
 	if (qc_idx >= sdebug_max_queue)
 		return 0;
 
+	spin_lock_irqsave(&sqp->qc_lock, iflags);
+
 	for (first = true; first || qc_idx + 1 < sdebug_max_queue; )   {
-		if (!locked) {
-			spin_lock_irqsave(&sqp->qc_lock, iflags);
-			locked = true;
-		}
 		if (first) {
 			first = false;
 			if (!test_bit(qc_idx, sqp->in_use_bm))
@@ -7586,14 +7583,15 @@  static int sdebug_blk_mq_poll(struct Scsi_Host *shost, unsigned int queue_num)
 		}
 		WRITE_ONCE(sd_dp->defer_t, SDEB_DEFER_NONE);
 		spin_unlock_irqrestore(&sqp->qc_lock, iflags);
-		locked = false;
 		scsi_done(scp); /* callback to mid level */
 		num_entries++;
+		spin_lock_irqsave(&sqp->qc_lock, iflags);
 		if (find_first_bit(sqp->in_use_bm, sdebug_max_queue) >= sdebug_max_queue)
-			break;	/* if no more then exit without retaking spinlock */
+			break;
 	}
-	if (locked)
-		spin_unlock_irqrestore(&sqp->qc_lock, iflags);
+
+	spin_unlock_irqrestore(&sqp->qc_lock, iflags);
+
 	if (num_entries > 0)
 		atomic_add(num_entries, &sdeb_mq_poll_count);
 	return num_entries;