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scsi_debug: deadlock between completions and surprise module removal

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A deadlock has been reported when the completion
of SCSI commands (simulated by a timer) was surprised
by a module removal. This patch removes one half of
the offending locks around timer deletions. This fix
is applied both to stop_all_queued() which is were
the deadlock was discovered and stop_queued_cmnd()
which has very similar logic.

This patch should be applied both to the lk 3.17 tree
and Christoph's drivers-for-3.18 tree.

Tested-and-reported-by: Milan Broz <gmazyland@gmail.com>
Signed-off-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Douglas Gilbert 2014-08-31 19:09:59 -04:00 committed by Christoph Hellwig
parent a41a9ad3bb
commit db525fce95
1 changed files with 19 additions and 14 deletions
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33
drivers/scsi/scsi_debug.c
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@ -2743,6 +2743,13 @@ static int stop_queued_cmnd(struct scsi_cmnd *cmnd)
if (test_bit(k, queued_in_use_bm)) {
sqcp = &queued_arr[k];
if (cmnd == sqcp->a_cmnd) {
devip = (struct sdebug_dev_info *)
cmnd->device->hostdata;
if (devip)
atomic_dec(&devip->num_in_q);
sqcp->a_cmnd = NULL;
spin_unlock_irqrestore(&queued_arr_lock,
iflags);
if (scsi_debug_ndelay > 0) {
if (sqcp->sd_hrtp)
hrtimer_cancel(
@ -2755,18 +2762,13 @@ static int stop_queued_cmnd(struct scsi_cmnd *cmnd)
if (sqcp->tletp)
tasklet_kill(sqcp->tletp);
}
__clear_bit(k, queued_in_use_bm);
devip = (struct sdebug_dev_info *)
cmnd->device->hostdata;
if (devip)
atomic_dec(&devip->num_in_q);
sqcp->a_cmnd = NULL;
break;
clear_bit(k, queued_in_use_bm);
return 1;
}
}
}
spin_unlock_irqrestore(&queued_arr_lock, iflags);
return (k < qmax) ? 1 : 0;
return 0;
}
/* Deletes (stops) timers or tasklets of all queued commands */
@ -2782,6 +2784,13 @@ static void stop_all_queued(void)
if (test_bit(k, queued_in_use_bm)) {
sqcp = &queued_arr[k];
if (sqcp->a_cmnd) {
devip = (struct sdebug_dev_info *)
sqcp->a_cmnd->device->hostdata;
if (devip)
atomic_dec(&devip->num_in_q);
sqcp->a_cmnd = NULL;
spin_unlock_irqrestore(&queued_arr_lock,
iflags);
if (scsi_debug_ndelay > 0) {
if (sqcp->sd_hrtp)
hrtimer_cancel(
@ -2794,12 +2803,8 @@ static void stop_all_queued(void)
if (sqcp->tletp)
tasklet_kill(sqcp->tletp);
}
__clear_bit(k, queued_in_use_bm);
devip = (struct sdebug_dev_info *)
sqcp->a_cmnd->device->hostdata;
if (devip)
atomic_dec(&devip->num_in_q);
sqcp->a_cmnd = NULL;
clear_bit(k, queued_in_use_bm);
spin_lock_irqsave(&queued_arr_lock, iflags);
}
}
}