netfilter: nf_tables: consolidate tracing invocations

* JUMP and GOTO are equivalent except for JUMP pushing the current
  context to the stack

* RETURN and implicit RETURN (CONTINUE) are equivalent except that
  the logged rule number differs

Result:

  nft_do_chain              | -112
 1 function changed, 112 bytes removed, diff: -112
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_core.c

@@ -170,26 +170,23 @@ nft_do_chain(struct nft_pktinfo *pkt, const struct nf_hook_ops *ops)
 
 	switch (data[NFT_REG_VERDICT].verdict) {
 	case NFT_JUMP:
-		nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RULE);
-
 		BUG_ON(stackptr >= NFT_JUMP_STACK_SIZE);
 		jumpstack[stackptr].chain = chain;
 		jumpstack[stackptr].rule  = rule;
 		jumpstack[stackptr].rulenum = rulenum;
 		stackptr++;
-		chain = data[NFT_REG_VERDICT].chain;
-		goto do_chain;
+		/* fall through */
 	case NFT_GOTO:
 		nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RULE);
 
 		chain = data[NFT_REG_VERDICT].chain;
 		goto do_chain;
+	case NFT_CONTINUE:
+		rulenum++;
+		/* fall through */
 	case NFT_RETURN:
 		nft_trace_packet(pkt, chain, rulenum, NFT_TRACE_RETURN);
 		break;
-	case NFT_CONTINUE:
-		nft_trace_packet(pkt, chain, ++rulenum, NFT_TRACE_RETURN);
-		break;
 	default:
 		WARN_ON(1);
 	}