On 4/2/22 00:30, gregkh@linuxfoundation.org wrote:

The patch below does not apply to the 5.17-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

Greg,

b05d4e481eff ("scsi: scsi_debug: Refine sdebug_blk_mq_poll()") which this patch fixes is not in 5.17 kernel, so there is no need for this backport.

Thanks.

------------------ original commit in Linus's tree ------------------

From 3fd07aecb75003fbcb0b7c3124d12f71ffd360d8 Mon Sep 17 00:00:00 2001 From: Damien Le Moal damien.lemoal@opensource.wdc.com Date: Tue, 1 Mar 2022 20:30:09 +0900 Subject: [PATCH] scsi: scsi_debug: Fix qc_lock use in sdebug_blk_mq_poll()

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.

Link: https://lore.kernel.org/r/20220301113009.595857-3-damien.lemoal@opensource.w... 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 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 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;