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

This patch moves the "#ifdef CONFIG_XXX" check into the "if/else"
statement itself.  The change is done for the bpf_setsockopt()
function only.  It will make the latter patches easier to follow
without the surrounding ifdef macro.

Reviewed-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/20220817061758.4178374-1-kafai@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

net/core/filter.c

@@ -5116,8 +5116,7 @@ static int __bpf_setsockopt(struct sock *sk, int level, int optname,
 		default:
 			ret = -EINVAL;
 		}
-#ifdef CONFIG_INET
-	} else if (level == SOL_IP) {
+	} else if (IS_ENABLED(CONFIG_INET) && level == SOL_IP) {
 		if (optlen != sizeof(int) || sk->sk_family != AF_INET)
 			return -EINVAL;
 
@@ -5138,8 +5137,7 @@ static int __bpf_setsockopt(struct sock *sk, int level, int optname,
 		default:
 			ret = -EINVAL;
 		}
-#if IS_ENABLED(CONFIG_IPV6)
-	} else if (level == SOL_IPV6) {
+	} else if (IS_ENABLED(CONFIG_IPV6) && level == SOL_IPV6) {
 		if (optlen != sizeof(int) || sk->sk_family != AF_INET6)
 			return -EINVAL;
 
@@ -5160,8 +5158,7 @@ static int __bpf_setsockopt(struct sock *sk, int level, int optname,
 		default:
 			ret = -EINVAL;
 		}
-#endif
-	} else if (level == SOL_TCP &&
+	} else if (IS_ENABLED(CONFIG_INET) && level == SOL_TCP &&
 		   sk->sk_prot->setsockopt == tcp_setsockopt) {
 		if (optname == TCP_CONGESTION) {
 			char name[TCP_CA_NAME_MAX];
@@ -5253,7 +5250,6 @@ static int __bpf_setsockopt(struct sock *sk, int level, int optname,
 				ret = -EINVAL;
 			}
 		}
-#endif
 	} else {
 		ret = -EINVAL;
 	}