rhashtable: Add parent argument to mutex_is_held

Currently mutex_is_held can only test locks in the that are global
since it takes no arguments.  This prevents rhashtable from being
used in places where locks are lock, e.g., per-namespace locks.

This patch adds a parent field to mutex_is_held and rhashtable_params
so that local locks can be used (and tested).

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/rhashtable.h

@@ -66,7 +66,8 @@ struct rhashtable_params {
 	bool			(*shrink_decision)(const struct rhashtable *ht,
 						   size_t new_size);
 #ifdef CONFIG_PROVE_LOCKING
-	int			(*mutex_is_held)(void);
+	int			(*mutex_is_held)(void *parent);
+	void			*parent;
 #endif
 };