[SCSI] scsi_dh_alua: fix deadlock in stpg_endio

The use of blk_execute_rq_nowait() implies __blk_put_request() is needed
in stpg_endio() rather than blk_put_request() -- blk_finish_request() is
called with queue lock already held.

Signed-off-by: Joseph Gruher <joseph.r.gruher@intel.com>
Signed-off-by: Ilgu Hong <ilgu.hong@promise.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@kernel.org
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/scsi/device_handler/scsi_dh_alua.c

@@ -285,7 +285,8 @@ static void stpg_endio(struct request *req, int error)
 			    print_alua_state(h->state));
 	}
 done:
-	blk_put_request(req);
+	req->end_io_data = NULL;
+	__blk_put_request(req->q, req);
 	if (h->callback_fn) {
 		h->callback_fn(h->callback_data, err);
 		h->callback_fn = h->callback_data = NULL;