[PATCH] device-mapper: fix deadlocks in core (prep)

Some code tidy-ups in preparation for the next patches.  Change
dm_table_pre/postsuspend_targets to accept NULL.  Use dm_suspended()
throughout.

Signed-Off-By: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index a5a4c0e..a6d3baa 100644
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -869,11 +869,17 @@
 
 void dm_table_presuspend_targets(struct dm_table *t)
 {
+	if (!t)
+		return;
+
 	return suspend_targets(t, 0);
 }
 
 void dm_table_postsuspend_targets(struct dm_table *t)
 {
+	if (!t)
+		return;
+
 	return suspend_targets(t, 1);
 }