dm mpath: avoid attempting to activate null path

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>

diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c
index 4840733cd9032c48a1253a8fae8ebdea2d4c09cd..58b1015260faa340cb26d4206b3b3cc615c74862 100644 (file)
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -441,13 +441,13 @@ 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;