bpf: Embed kernel CONFIG check into the if statement in bpf_getsockopt

This patch moves the "#ifdef CONFIG_XXX" check into the "if/else"
statement itself.  The change is done for the bpf_getsockopt()
function only.  It will make the latter patches easier to follow
without the surrounding ifdef macro.
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20220902002906.2893572-1-kafai@fb.comSigned-off-by: Alexei Starovoitov <ast@kernel.org>

net/core/filter.c

@@ -5222,8 +5222,8 @@ static int __bpf_getsockopt(struct sock *sk, int level, int optname,
 		default:
 			goto err_clear;
 		}
-#ifdef CONFIG_INET
-	} else if (level == SOL_TCP && sk->sk_prot->getsockopt == tcp_getsockopt) {
+	} else if (IS_ENABLED(CONFIG_INET) &&
+		   level == SOL_TCP && sk->sk_prot->getsockopt == tcp_getsockopt) {
 		struct inet_connection_sock *icsk;
 		struct tcp_sock *tp;
 
@@ -5247,7 +5247,7 @@ static int __bpf_getsockopt(struct sock *sk, int level, int optname,
 		default:
 			goto err_clear;
 		}
-	} else if (level == SOL_IP) {
+	} else if (IS_ENABLED(CONFIG_INET) && level == SOL_IP) {
 		struct inet_sock *inet = inet_sk(sk);
 
 		if (optlen != sizeof(int) || sk->sk_family != AF_INET)
@@ -5261,8 +5261,7 @@ static int __bpf_getsockopt(struct sock *sk, int level, int optname,
 		default:
 			goto err_clear;
 		}
-#if IS_ENABLED(CONFIG_IPV6)
-	} else if (level == SOL_IPV6) {
+	} else if (IS_ENABLED(CONFIG_IPV6) && level == SOL_IPV6) {
 		struct ipv6_pinfo *np = inet6_sk(sk);
 
 		if (optlen != sizeof(int) || sk->sk_family != AF_INET6)
@@ -5276,8 +5275,6 @@ static int __bpf_getsockopt(struct sock *sk, int level, int optname,
 		default:
 			goto err_clear;
 		}
-#endif
-#endif
 	} else {
 		goto err_clear;
 	}