From: Mike Snitzer <snitzer@redhat.com>

If the requested scsi_dh module is already loaded then skip
request_module().

Multipath table loads can hang in an unnecessary __request_module.

Reported-by: Ben Marzinski <bmarzins@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

---
drivers/md/dm-mpath.c |    4 ++--
 drivers/md/dm-mpath.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux-3.4-rc6/drivers/md/dm-mpath.c
===================================================================
--- linux-3.4-rc6.orig/drivers/md/dm-mpath.c
+++ linux-3.4-rc6/drivers/md/dm-mpath.c
@@ -718,8 +718,8 @@ static int parse_hw_handler(struct dm_ar
 		return 0;
 
 	m->hw_handler_name = kstrdup(dm_shift_arg(as), GFP_KERNEL);
-	request_module("scsi_dh_%s", m->hw_handler_name);
-	if (scsi_dh_handler_exist(m->hw_handler_name) == 0) {
+	if (!try_then_request_module(scsi_dh_handler_exist(m->hw_handler_name),
+				     "scsi_dh_%s", m->hw_handler_name)) {
 		ti->error = "unknown hardware handler type";
 		ret = -EINVAL;
 		goto fail;