+static void *rhashtable_try_insert(struct rhashtable *ht, const void *key,
+ struct rhash_head *obj)
+{
+ struct bucket_table *new_tbl;
+ struct bucket_table *tbl;
+ unsigned int hash;
+ spinlock_t *lock;
+ void *data;
+
+ tbl = rcu_dereference(ht->tbl);
+
+ /* All insertions must grab the oldest table containing
+ * the hashed bucket that is yet to be rehashed.
+ */
+ for (;;) {
+ hash = rht_head_hashfn(ht, tbl, obj, ht->p);
+ lock = rht_bucket_lock(tbl, hash);
+ spin_lock_bh(lock);
+
+ if (tbl->rehash <= hash)
+ break;
+
+ spin_unlock_bh(lock);
+ tbl = rcu_dereference(tbl->future_tbl);
+ }
+
+ data = rhashtable_lookup_one(ht, tbl, hash, key, obj);
+ new_tbl = rhashtable_insert_one(ht, tbl, hash, obj, data);
+ if (PTR_ERR(new_tbl) != -EEXIST)
+ data = ERR_CAST(new_tbl);
+
+ while (!IS_ERR_OR_NULL(new_tbl)) {
+ tbl = new_tbl;
+ hash = rht_head_hashfn(ht, tbl, obj, ht->p);
+ spin_lock_nested(rht_bucket_lock(tbl, hash),
+ SINGLE_DEPTH_NESTING);
+
+ data = rhashtable_lookup_one(ht, tbl, hash, key, obj);
+ new_tbl = rhashtable_insert_one(ht, tbl, hash, obj, data);
+ if (PTR_ERR(new_tbl) != -EEXIST)
+ data = ERR_CAST(new_tbl);
+
+ spin_unlock(rht_bucket_lock(tbl, hash));
+ }
+
+ spin_unlock_bh(lock);
+
+ if (PTR_ERR(data) == -EAGAIN)
+ data = ERR_PTR(rhashtable_insert_rehash(ht, tbl) ?:
+ -EAGAIN);
+
+ return data;
+}
+
+void *rhashtable_insert_slow(struct rhashtable *ht, const void *key,
+ struct rhash_head *obj)
+{
+ void *data;
+
+ do {
+ rcu_read_lock();
+ data = rhashtable_try_insert(ht, key, obj);
+ rcu_read_unlock();
+ } while (PTR_ERR(data) == -EAGAIN);
+
+ return data;