locking/lockdep: Shrink struct lock_class_key

Shrink struct lock_class_key; we never store anything in subkeys[], we
only use the addresses.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 43fb35b..79c3873 100644 (file)
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -58,8 +58,10 @@ struct lockdep_subclass_key {
 
 /* hash_entry is used to keep track of dynamically allocated keys. */
 struct lock_class_key {
-       struct hlist_node               hash_entry;
-       struct lockdep_subclass_key     subkeys[MAX_LOCKDEP_SUBCLASSES];
+       union {
+               struct hlist_node               hash_entry;
+               struct lockdep_subclass_key     subkeys[MAX_LOCKDEP_SUBCLASSES];
+       };
 };
 
 extern struct lock_class_key __lockdep_no_validate__;