On 4/2/22 00:30, gregkh@xxxxxxxxxxxxxxxxxxx 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@xxxxxxxxxxxxxxx>.
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@xxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxx
Fixes: b05d4e481eff ("scsi: scsi_debug: Refine sdebug_blk_mq_poll()")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
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;
--
Damien Le Moal
Western Digital Research
