dm mpath: avoid attempting to activate null path

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@us.ibm.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index c2fcf28b4c7022b2ec66e0c9d661e8a87b5279c8..61f57531de9d3fb55fb0ca4631715c6bc2b1065a 100644 (file)
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -427,13 +427,13 @@ static void process_queued_ios(struct work_struct *work)
                __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;