Get event notification working in multipath.
--- diff/drivers/md/dm-mpath.c	2004-01-16 16:40:21.000000000 +0000
+++ source/drivers/md/dm-mpath.c	2004-01-16 18:22:25.000000000 +0000
@@ -64,7 +64,7 @@
 	struct bio_list test_ios;
 
 	unsigned test_interval;
-	atomic_t trigger_event;
+	unsigned trigger_event;
 };
 
 static struct path *alloc_path(void)
@@ -197,6 +197,7 @@
 	atomic_inc(&path->fail_total);
 	list_move(&path->list, &path->pg->invalid_paths);
 	path->pg->ps->type->set_path_state(path->pg->ps, path, 0);
+	path->pg->m->trigger_event = 1;
 }
 
 static void __recover_path(struct path *path)
@@ -208,6 +209,7 @@
 	list_move(&path->list, &path->pg->valid_paths);
 	path->pg->ps->type->set_path_state(path->pg->ps, path, 1);
 	path->has_failed = 0;
+	path->pg->m->trigger_event = 1;
 }
 
 static int test_endio(struct bio *bio, unsigned int done, int error)
@@ -294,6 +296,7 @@
 /* Multipathd does this every time it runs, returns a sleep duration hint */
 static jiffy_t do_work(void)
 {
+	unsigned long flags;
 	struct multipath *m;
 
 	spin_lock(&_mpath_lock);
@@ -302,8 +305,12 @@
 		iterate_paths(m, test_path);
 		submit_ios(bio_list_get(&m->test_ios));
 
-		if (atomic_dec_and_test(&m->trigger_event))
+		spin_lock_irqsave(&m->path_lock, flags);
+		if (m->trigger_event) {
 			dm_table_event(m->ti->table);
+			m->trigger_event = 0;
+		}
+		spin_unlock_irqrestore(&m->path_lock, flags);
 	}
 	spin_unlock(&_mpath_lock);