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 (file)
--- a/include/linux/rhashtable.h
+++ b/include/linux/rhashtable.h
@@ -173,7 +173,7 @@ struct rhashtable_walker {
 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 *rhashtable_insert_slow(struct rhashtable *ht,
                                            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 @@ static inline int rhashtable_replace_fast(
        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 */

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 5ba520b..97e3cf0 100644 (file)
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c
@@ -489,10 +489,9 @@ exit:
 EXPORT_SYMBOL_GPL(rhashtable_insert_slow);
 
 /**
- * rhashtable_walk_init - Initialise an iterator
+ * rhashtable_walk_enter - Initialise an iterator
  * @ht:                Table to walk over
  * @iter:      Hash table Iterator
- * @gfp:       GFP flags for allocations
  *
  * This function prepares a hash table walk.
  *
@@ -507,30 +506,22 @@ EXPORT_SYMBOL_GPL(rhashtable_insert_slow);
  * This function may sleep so you must not call it from interrupt
  * context or with spin locks held.
  *
- * You must call rhashtable_walk_exit if this function returns
- * successfully.
+ * You must call rhashtable_walk_exit after this function returns.
  */
-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)
 {
        iter->ht = ht;
        iter->p = NULL;
        iter->slot = 0;
        iter->skip = 0;
 
-       iter->walker = kmalloc(sizeof(*iter->walker), gfp);
-       if (!iter->walker)
-               return -ENOMEM;
-
        spin_lock(&ht->lock);
-       iter->walker->tbl =
+       iter->walker.tbl =
                rcu_dereference_protected(ht->tbl, lockdep_is_held(&ht->lock));
-       list_add(&iter->walker->list, &iter->walker->tbl->walkers);
+       list_add(&iter->walker.list, &iter->walker.tbl->walkers);
        spin_unlock(&ht->lock);
-
-       return 0;
 }
-EXPORT_SYMBOL_GPL(rhashtable_walk_init);
+EXPORT_SYMBOL_GPL(rhashtable_walk_enter);
 
 /**
  * rhashtable_walk_exit - Free an iterator
@@ -541,10 +532,9 @@ EXPORT_SYMBOL_GPL(rhashtable_walk_init);
 void rhashtable_walk_exit(struct rhashtable_iter *iter)
 {
        spin_lock(&iter->ht->lock);
-       if (iter->walker->tbl)
-               list_del(&iter->walker->list);
+       if (iter->walker.tbl)
+               list_del(&iter->walker.list);
        spin_unlock(&iter->ht->lock);
-       kfree(iter->walker);
 }
 EXPORT_SYMBOL_GPL(rhashtable_walk_exit);
 
@@ -570,12 +560,12 @@ int rhashtable_walk_start(struct rhashtable_iter *iter)
        rcu_read_lock();
 
        spin_lock(&ht->lock);
-       if (iter->walker->tbl)
-               list_del(&iter->walker->list);
+       if (iter->walker.tbl)
+               list_del(&iter->walker.list);
        spin_unlock(&ht->lock);
 
-       if (!iter->walker->tbl) {
-               iter->walker->tbl = rht_dereference_rcu(ht->tbl, ht);
+       if (!iter->walker.tbl) {
+               iter->walker.tbl = rht_dereference_rcu(ht->tbl, ht);
                return -EAGAIN;
        }
 
@@ -597,7 +587,7 @@ EXPORT_SYMBOL_GPL(rhashtable_walk_start);
  */
 void *rhashtable_walk_next(struct rhashtable_iter *iter)
 {
-       struct bucket_table *tbl = iter->walker->tbl;
+       struct bucket_table *tbl = iter->walker.tbl;
        struct rhashtable *ht = iter->ht;
        struct rhash_head *p = iter->p;
 
@@ -630,8 +620,8 @@ next:
        /* Ensure we see any new tables. */
        smp_rmb();
 
-       iter->walker->tbl = rht_dereference_rcu(tbl->future_tbl, ht);
-       if (iter->walker->tbl) {
+       iter->walker.tbl = rht_dereference_rcu(tbl->future_tbl, ht);
+       if (iter->walker.tbl) {
                iter->slot = 0;
                iter->skip = 0;
                return ERR_PTR(-EAGAIN);
@@ -651,7 +641,7 @@ void rhashtable_walk_stop(struct rhashtable_iter *iter)
        __releases(RCU)
 {
        struct rhashtable *ht;
-       struct bucket_table *tbl = iter->walker->tbl;
+       struct bucket_table *tbl = iter->walker.tbl;
 
        if (!tbl)
                goto out;
@@ -660,9 +650,9 @@ void rhashtable_walk_stop(struct rhashtable_iter *iter)
 
        spin_lock(&ht->lock);
        if (tbl->rehash < tbl->size)
-               list_add(&iter->walker->list, &tbl->walkers);
+               list_add(&iter->walker.list, &tbl->walkers);
        else
-               iter->walker->tbl = NULL;
+               iter->walker.tbl = NULL;
        spin_unlock(&ht->lock);
 
        iter->p = NULL;