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

Greg KH
2009-02-11T00:44:23Z

[-- Attachment #1: dm-mpath-avoid-attempting-to-activate-null-path.patch --]
[-- Type: text/plain, Size: 1279 bytes --]

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

From: Chandra Seetharaman <sekharan@us.ibm.com>

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>

---
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;