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scsi: scsi_debug: Fix in_use bitmap corruption

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Heavy testing indicates the irqsave() spinlock around the __set_bit() is
insufficient to stop following clear_bit() calls being rarely applied
out-of-order. Also the nearby failed kzalloc() path leading to
SCSI_MLQUEUE_HOST_BUSY does not properly undo the in_use bitmap and
num_in_q, fix.

Link: https://lore.kernel.org/r/20200702145355.522283-1-dgilbert@interlog.com
Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Douglas Gilbert 2020-07-02 10:53:55 -04:00 committed by Martin K. Petersen
parent 93bf02e5a2
commit 74595c044c
1 changed files with 6 additions and 3 deletions
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9
drivers/scsi/scsi_debug.c
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@ -5430,7 +5430,7 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
else
return SCSI_MLQUEUE_HOST_BUSY;
}
__set_bit(k, sqp->in_use_bm);
set_bit(k, sqp->in_use_bm);
atomic_inc(&devip->num_in_q);
sqcp = &sqp->qc_arr[k];
sqcp->a_cmnd = cmnd;
@ -5439,10 +5439,13 @@ static int schedule_resp(struct scsi_cmnd *cmnd, struct sdebug_dev_info *devip,
spin_unlock_irqrestore(&sqp->qc_lock, iflags);
if (unlikely(sdebug_every_nth && sdebug_any_injecting_opt))
setup_inject(sqp, sqcp);
if (sd_dp == NULL) {
if (!sd_dp) {
sd_dp = kzalloc(sizeof(*sd_dp), GFP_ATOMIC);
if (sd_dp == NULL)
if (!sd_dp) {
atomic_dec(&devip->num_in_q);
clear_bit(k, sqp->in_use_bm);
return SCSI_MLQUEUE_HOST_BUSY;
}
new_sd_dp = true;
} else {
new_sd_dp = false;