[patch 45/56] dm mpath: avoid attempting to activate null path

[Greg KH]

2.6.27-stable review patch.  If anyone has any objections, please let us know.
------------------

From: Chandra Seetharaman <sekharan@xxxxxxxxxx>

commit b81aa1c79201cb424114fd198607951900babe18 upstream.

Path activation code is called even when the pgpath is NULL. This could
lead to a panic in activate_path(). Such a panic is seen in -rt kernel.

This problem has been there before the pg_init() was moved to a
workqueue.

Signed-off-by: Chandra Seetharaman <sekharan@xxxxxxxxxx>
Signed-off-by: Alasdair G Kergon <agk@xxxxxxxxxx>
Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

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

--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -427,13 +427,13 @@ static void process_queued_ios(struct wo
 		__choose_pgpath(m);
 
 	pgpath = m->current_pgpath;
-	m->pgpath_to_activate = m->current_pgpath;
 
 	if ((pgpath && !m->queue_io) ||
 	    (!pgpath && !m->queue_if_no_path))
 		must_queue = 0;
 
-	if (m->pg_init_required && !m->pg_init_in_progress) {
+	if (m->pg_init_required && !m->pg_init_in_progress && pgpath) {
+		m->pgpath_to_activate = pgpath;
 		m->pg_init_count++;
 		m->pg_init_required = 0;
 		m->pg_init_in_progress = 1;

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