netfilter: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <[e-mail]>
Signed-off-by: Pablo Neira Ayuso <[e-mail]>

net/bridge/netfilter/ebtables.c

···
 			size_kern = match_size;
 		module_put(match->me);
 		break;
-	case EBT_COMPAT_WATCHER: /* fallthrough */
+	case EBT_COMPAT_WATCHER:
 	case EBT_COMPAT_TARGET:
 		wt = xt_request_find_target(NFPROTO_BRIDGE, name,
 					    mwt->u.revision);

net/netfilter/ipset/ip_set_core.c

···
 				goto next_set;
 			if (set->variant->uref)
 				set->variant->uref(set, cb, true);
-			/* fall through */
+			fallthrough;
 		default:
 			ret = set->variant->list(set, skb, cb);
 			if (!cb->args[IPSET_CB_ARG0])

net/netfilter/nf_conntrack_h323_asn1.c

···
 	case 4:
 		v |= *bs->cur++;
 		v <<= 8;
-		/* fall through */
+		fallthrough;
 	case 3:
 		v |= *bs->cur++;
 		v <<= 8;
-		/* fall through */
+		fallthrough;
 	case 2:
 		v |= *bs->cur++;
 		v <<= 8;
-		/* fall through */
+		fallthrough;
 	case 1:
 		v |= *bs->cur++;
 		break;

net/netfilter/nf_conntrack_proto.c

···
 	switch (nfproto) {
 	case NFPROTO_BRIDGE:
 		nf_ct_netns_do_put(net, NFPROTO_BRIDGE);
-		/* fall through */
+		fallthrough;
 	case NFPROTO_INET:
 		nf_ct_netns_do_put(net, NFPROTO_IPV4);
 		nf_ct_netns_do_put(net, NFPROTO_IPV6);

net/netfilter/nf_conntrack_proto_tcp.c

···
 				return -NF_REPEAT;
 			return NF_DROP;
 		}
-		/* Fall through */
+		fallthrough;
 	case TCP_CONNTRACK_IGNORE:
 		/* Ignored packets:
 		 *

net/netfilter/nf_conntrack_standalone.c

···
 			   ntohs(tuple->src.u.tcp.port),
 			   ntohs(tuple->dst.u.tcp.port));
 		break;
-	case IPPROTO_UDPLITE: /* fallthrough */
+	case IPPROTO_UDPLITE:
 	case IPPROTO_UDP:
 		seq_printf(s, "sport=%hu dport=%hu ",
 			   ntohs(tuple->src.u.udp.port),

net/netfilter/nf_nat_core.c

···
 	static const unsigned int max_attempts = 128;
 
 	switch (tuple->dst.protonum) {
-	case IPPROTO_ICMP: /* fallthrough */
+	case IPPROTO_ICMP:
 	case IPPROTO_ICMPV6:
 		/* id is same for either direction... */
 		keyptr = &tuple->src.u.icmp.id;
···
 		}
 		goto find_free_id;
 #endif
-	case IPPROTO_UDP:	/* fallthrough */
-	case IPPROTO_UDPLITE:	/* fallthrough */
-	case IPPROTO_TCP:	/* fallthrough */
-	case IPPROTO_SCTP:	/* fallthrough */
-	case IPPROTO_DCCP:	/* fallthrough */
+	case IPPROTO_UDP:
+	case IPPROTO_UDPLITE:
+	case IPPROTO_TCP:
+	case IPPROTO_SCTP:
+	case IPPROTO_DCCP:
 		if (maniptype == NF_NAT_MANIP_SRC)
 			keyptr = &tuple->src.u.all;
 		else

net/netfilter/nf_synproxy_core.c

···
 		nf_ct_seqadj_init(ct, ctinfo, 0);
 		synproxy->tsoff = 0;
 		this_cpu_inc(snet->stats->conn_reopened);
-
-		/* fall through */
+		fallthrough;
 	case TCP_CONNTRACK_SYN_SENT:
 		if (!synproxy_parse_options(skb, thoff, th, &opts))
 			return NF_DROP;
···
 		nf_ct_seqadj_init(ct, ctinfo, 0);
 		synproxy->tsoff = 0;
 		this_cpu_inc(snet->stats->conn_reopened);
-
-		/* fall through */
+		fallthrough;
 	case TCP_CONNTRACK_SYN_SENT:
 		if (!synproxy_parse_options(skb, thoff, th, &opts))
 			return NF_DROP;

net/netfilter/nf_tables_api.c

···
 	case NFT_TRANS_ABORT:
 	case NFT_TRANS_RELEASE:
 		set->use--;
-		/* fall through */
+		fallthrough;
 	default:
 		nf_tables_unbind_set(ctx, set, binding,
 				     phase == NFT_TRANS_COMMIT);
···
 	case NFT_TRANS_ABORT:
 	case NFT_TRANS_RELEASE:
 		flowtable->use--;
-		/* fall through */
+		fallthrough;
 	default:
 		return;
 	}
···
 		break;
 	case NFT_VALIDATE_NEED:
 		nft_validate_state_update(net, NFT_VALIDATE_DO);
-		/* fall through */
+		fallthrough;
 	case NFT_VALIDATE_DO:
 		list_for_each_entry(table, &net->nft.tables, list) {
 			if (nft_table_validate(net, table) < 0)
···
 		default:
 			return -EINVAL;
 		}
-		/* fall through */
+		fallthrough;
 	case NFT_CONTINUE:
 	case NFT_BREAK:
 	case NFT_RETURN:

net/netfilter/nf_tables_core.c

···
 		jumpstack[stackptr].chain = chain;
 		jumpstack[stackptr].rules = rules + 1;
 		stackptr++;
-		/* fall through */
+		fallthrough;
 	case NFT_GOTO:
 		nft_trace_packet(&info, chain, rule,
 				 NFT_TRACETYPE_RULE);

net/netfilter/nfnetlink_cttimeout.c

···
 	case IPPROTO_TCP:
 		timeouts = nf_tcp_pernet(net)->timeouts;
 		break;
-	case IPPROTO_UDP: /* fallthrough */
+	case IPPROTO_UDP:
 	case IPPROTO_UDPLITE:
 		timeouts = nf_udp_pernet(net)->timeouts;
 		break;

net/netfilter/nft_cmp.c

···
 	case NFT_CMP_LT:
 		if (d == 0)
 			goto mismatch;
-		/* fall through */
+		fallthrough;
 	case NFT_CMP_LTE:
 		if (d > 0)
 			goto mismatch;
···
 	case NFT_CMP_GT:
 		if (d == 0)
 			goto mismatch;
-		/* fall through */
+		fallthrough;
 	case NFT_CMP_GTE:
 		if (d < 0)
 			goto mismatch;

net/netfilter/nft_ct.c

···
 		return;
 	}
 #endif
-	case NFT_CT_BYTES: /* fallthrough */
+	case NFT_CT_BYTES:
 	case NFT_CT_PKTS: {
 		const struct nf_conn_acct *acct = nf_conn_acct_find(ct);
 		u64 count = 0;
···
 		help6 = nf_conntrack_helper_try_module_get(name, family,
 							   priv->l4proto);
 		break;
-	case NFPROTO_NETDEV: /* fallthrough */
-	case NFPROTO_BRIDGE: /* same */
+	case NFPROTO_NETDEV:
+	case NFPROTO_BRIDGE:
 	case NFPROTO_INET:
 		help4 = nf_conntrack_helper_try_module_get(name, NFPROTO_IPV4,
 							   priv->l4proto);

net/netfilter/nft_fib.c

···
 	unsigned int hooks;
 
 	switch (priv->result) {
-	case NFT_FIB_RESULT_OIF: /* fallthrough */
+	case NFT_FIB_RESULT_OIF:
 	case NFT_FIB_RESULT_OIFNAME:
 		hooks = (1 << NF_INET_PRE_ROUTING);
 		break;

net/netfilter/nft_payload.c

···
 	case IPPROTO_UDP:
 		if (!nft_payload_udp_checksum(skb, pkt->xt.thoff))
 			return -1;
-		/* Fall through. */
+		fallthrough;
 	case IPPROTO_UDPLITE:
 		*l4csum_offset = offsetof(struct udphdr, check);
 		break;

net/netfilter/utils.c

···
 			skb->ip_summed = CHECKSUM_UNNECESSARY;
 			break;
 		}
-		/* fall through */
+		fallthrough;
 	case CHECKSUM_NONE:
 		if (protocol != IPPROTO_TCP && protocol != IPPROTO_UDP)
 			skb->csum = 0;
···
 	case CHECKSUM_COMPLETE:
 		if (len == skb->len - dataoff)
 			return nf_ip_checksum(skb, hook, dataoff, protocol);
-		/* fall through */
+		fallthrough;
 	case CHECKSUM_NONE:
 		skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol,
 					       skb->len - dataoff, 0);
···
 			skb->ip_summed = CHECKSUM_UNNECESSARY;
 			break;
 		}
-		/* fall through */
+		fallthrough;
 	case CHECKSUM_NONE:
 		skb->csum = ~csum_unfold(
 				csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
···
 	case CHECKSUM_COMPLETE:
 		if (len == skb->len - dataoff)
 			return nf_ip6_checksum(skb, hook, dataoff, protocol);
-		/* fall through */
+		fallthrough;
 	case CHECKSUM_NONE:
 		hsum = skb_checksum(skb, 0, dataoff, 0);
 		skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,

net/netfilter/x_tables.c

···
 		trav->curr = trav->curr->next;
 		if (trav->curr != trav->head)
 			break;
-		/* fall through */
+		fallthrough;
 	default:
 		return NULL;
 	}