netfilter: nf_tables: No need to check chain existence when tracing

nft_trace_notify() is called only from __nft_trace_packet(), which
assigns its parameter 'chain' to info->chain. __nft_trace_packet() in
turn later dereferences 'chain' unconditionally, which indicates that
it's never NULL. Same does nft_do_chain(), the only user of the tracing
infrastructure. Hence it is safe to assume the check removed here is not
needed.
Signed-off-by: NPhil Sutter <phil@nwl.cc>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_trace.c

@@ -217,14 +217,11 @@ void nft_trace_notify(struct nft_traceinfo *info)
 	if (trace_fill_id(skb, pkt->skb))
 		goto nla_put_failure;
 
-	if (info->chain) {
-		if (nla_put_string(skb, NFTA_TRACE_CHAIN,
-				   info->chain->name))
-			goto nla_put_failure;
-		if (nla_put_string(skb, NFTA_TRACE_TABLE,
-				   info->chain->table->name))
-			goto nla_put_failure;
-	}
+	if (nla_put_string(skb, NFTA_TRACE_CHAIN, info->chain->name))
+		goto nla_put_failure;
+
+	if (nla_put_string(skb, NFTA_TRACE_TABLE, info->chain->table->name))
+		goto nla_put_failure;
 
 	if (nf_trace_fill_rule_info(skb, info))
 		goto nla_put_failure;