From db525fce95f0ee39102f06f8599ced3f3f3af128 Mon Sep 17 00:00:00 2001 From: Douglas Gilbert Date: Sun, 31 Aug 2014 19:09:59 -0400 Subject: [PATCH] scsi_debug: deadlock between completions and surprise module removal 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 Signed-off-by: Douglas Gilbert Signed-off-by: Christoph Hellwig --- drivers/scsi/scsi_debug.c | 33 +++++++++++++++++++-------------- 1 file changed, 19 insertions(+), 14 deletions(-) diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c index 1c475e9a46ab..2b6d447ad6d6 100644 --- a/drivers/scsi/scsi_debug.c +++ b/drivers/scsi/scsi_debug.c @@ -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); } } } -- 2.30.2