+static int nf_tables_commit_chain_prepare(struct net *net, struct nft_chain *chain)
+{
+ struct nft_rule *rule;
+ unsigned int alloc = 0;
+ int i;
+
+ /* already handled or inactive chain? */
+ if (chain->rules_next || !nft_is_active_next(net, chain))
+ return 0;
+
+ rule = list_entry(&chain->rules, struct nft_rule, list);
+ i = 0;
+
+ list_for_each_entry_continue(rule, &chain->rules, list) {
+ if (nft_is_active_next(net, rule))
+ alloc++;
+ }
+
+ chain->rules_next = nf_tables_chain_alloc_rules(chain, alloc);
+ if (!chain->rules_next)
+ return -ENOMEM;
+
+ list_for_each_entry_continue(rule, &chain->rules, list) {
+ if (nft_is_active_next(net, rule))
+ chain->rules_next[i++] = rule;
+ }
+
+ chain->rules_next[i] = NULL;
+ return 0;
+}
+
+static void nf_tables_commit_chain_prepare_cancel(struct net *net)
+{
+ struct nft_trans *trans, *next;
+
+ list_for_each_entry_safe(trans, next, &net->nft.commit_list, list) {
+ struct nft_chain *chain = trans->ctx.chain;
+
+ if (trans->msg_type == NFT_MSG_NEWRULE ||
+ trans->msg_type == NFT_MSG_DELRULE) {
+ kvfree(chain->rules_next);
+ chain->rules_next = NULL;
+ }
+ }
+}
+
+static void __nf_tables_commit_chain_free_rules_old(struct rcu_head *h)
+{
+ struct nft_rules_old *o = container_of(h, struct nft_rules_old, h);
+
+ kvfree(o->start);
+}
+
+static void nf_tables_commit_chain_free_rules_old(struct nft_rule **rules)
+{
+ struct nft_rule **r = rules;
+ struct nft_rules_old *old;
+
+ while (*r)
+ r++;
+
+ r++; /* rcu_head is after end marker */
+ old = (void *) r;
+ old->start = rules;
+
+ call_rcu(&old->h, __nf_tables_commit_chain_free_rules_old);
+}
+
+static void nf_tables_commit_chain_active(struct net *net, struct nft_chain *chain)
+{
+ struct nft_rule **g0, **g1;
+ bool next_genbit;
+
+ next_genbit = nft_gencursor_next(net);
+
+ g0 = rcu_dereference_protected(chain->rules_gen_0,
+ lockdep_nfnl_is_held(NFNL_SUBSYS_NFTABLES));
+ g1 = rcu_dereference_protected(chain->rules_gen_1,
+ lockdep_nfnl_is_held(NFNL_SUBSYS_NFTABLES));
+
+ /* No changes to this chain? */
+ if (chain->rules_next == NULL) {
+ /* chain had no change in last or next generation */
+ if (g0 == g1)
+ return;
+ /*
+ * chain had no change in this generation; make sure next
+ * one uses same rules as current generation.
+ */
+ if (next_genbit) {
+ rcu_assign_pointer(chain->rules_gen_1, g0);
+ nf_tables_commit_chain_free_rules_old(g1);
+ } else {
+ rcu_assign_pointer(chain->rules_gen_0, g1);
+ nf_tables_commit_chain_free_rules_old(g0);
+ }
+
+ return;
+ }
+
+ if (next_genbit)
+ rcu_assign_pointer(chain->rules_gen_1, chain->rules_next);
+ else
+ rcu_assign_pointer(chain->rules_gen_0, chain->rules_next);
+
+ chain->rules_next = NULL;
+
+ if (g0 == g1)
+ return;
+
+ if (next_genbit)
+ nf_tables_commit_chain_free_rules_old(g1);
+ else
+ nf_tables_commit_chain_free_rules_old(g0);
+}
+