[SCSI] Make scsi_free_queue() kill pending SCSI commands

Make sure that SCSI device removal via scsi_remove_host() does finish
all pending SCSI commands. Currently that's not the case and hence
removal of a SCSI host during I/O can cause a deadlock. See also
"blkdev_issue_discard() hangs forever if underlying storage device is
removed" (http://bugzilla.kernel.org/show_bug.cgi?id=40472). See also
http://lkml.org/lkml/2011/8/27/6.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Cc: <stable@kernel.org>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index fc3f168decb4..b4d43ae76132 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1698,6 +1698,15 @@ struct request_queue *scsi_alloc_queue(struct scsi_device *sdev)
 
 void scsi_free_queue(struct request_queue *q)
 {
+        unsigned long flags;
+
+        WARN_ON(q->queuedata);
+
+        /* cause scsi_request_fn() to kill all non-finished requests */
+        spin_lock_irqsave(q->queue_lock, flags);
+        q->request_fn(q);
+        spin_unlock_irqrestore(q->queue_lock, flags);
+
         blk_cleanup_queue(q);
 }