rhashtable: Remove GFP flag from rhashtable_walk_init

The commit 8f6fd83c6c5ec66a4a70c728535ddcdfef4f3697 ("rhashtable:
accept GFP flags in rhashtable_walk_init") added a GFP flag argument
to rhashtable_walk_init because some users wish to use the walker
in an unsleepable context.

In fact we don't need to allocate memory in rhashtable_walk_init
at all.  The walker is always paired with an iterator so we could
just stash ourselves there.

This patch does that by introducing a new enter function to replace
the existing init function.  This way we don't have to churn all
the existing users again.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/rhashtable.h b/include/linux/rhashtable.h
index 3eef080..8b72ee7 100644
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -173,7 +173,7 @@
 struct rhashtable_iter {
 	struct rhashtable *ht;
 	struct rhash_head *p;
-	struct rhashtable_walker *walker;
+	struct rhashtable_walker walker;
 	unsigned int slot;
 	unsigned int skip;
 };
@@ -346,8 +346,8 @@
 					    struct bucket_table *old_tbl);
 int rhashtable_insert_rehash(struct rhashtable *ht, struct bucket_table *tbl);
 
-int rhashtable_walk_init(struct rhashtable *ht, struct rhashtable_iter *iter,
-			 gfp_t gfp);
+void rhashtable_walk_enter(struct rhashtable *ht,
+			   struct rhashtable_iter *iter);
 void rhashtable_walk_exit(struct rhashtable_iter *iter);
 int rhashtable_walk_start(struct rhashtable_iter *iter) __acquires(RCU);
 void *rhashtable_walk_next(struct rhashtable_iter *iter);
@@ -906,4 +906,12 @@
 	return err;
 }
 
+/* Obsolete function, do not use in new code. */
+static inline int rhashtable_walk_init(struct rhashtable *ht,
+				       struct rhashtable_iter *iter, gfp_t gfp)
+{
+	rhashtable_walk_enter(ht, iter);
+	return 0;
+}
+
 #endif /* _LINUX_RHASHTABLE_H */