net: lockless SO_PASSCRED, SO_PASSPIDFD and SO_PASSSEC

sock->flags are atomic, no need to hold the socket lock
in sk_setsockopt() for SO_PASSCRED, SO_PASSPIDFD and SO_PASSSEC.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/sock.c

@@ -1126,6 +1126,15 @@ int sk_setsockopt(struct sock *sk, int level, int optname,
 			return 0;
 		}
 		return -EPERM;
+	case SO_PASSSEC:
+		assign_bit(SOCK_PASSSEC, &sock->flags, valbool);
+		return 0;
+	case SO_PASSCRED:
+		assign_bit(SOCK_PASSCRED, &sock->flags, valbool);
+		return 0;
+	case SO_PASSPIDFD:
+		assign_bit(SOCK_PASSPIDFD, &sock->flags, valbool);
+		return 0;
 	}
 
 	sockopt_lock_sock(sk);
@@ -1248,14 +1257,6 @@ int sk_setsockopt(struct sock *sk, int level, int optname,
 	case SO_BSDCOMPAT:
 		break;
 
-	case SO_PASSCRED:
-		assign_bit(SOCK_PASSCRED, &sock->flags, valbool);
-		break;
-
-	case SO_PASSPIDFD:
-		assign_bit(SOCK_PASSPIDFD, &sock->flags, valbool);
-		break;
-
 	case SO_TIMESTAMP_OLD:
 	case SO_TIMESTAMP_NEW:
 	case SO_TIMESTAMPNS_OLD:
@@ -1361,9 +1362,6 @@ int sk_setsockopt(struct sock *sk, int level, int optname,
 			sock_valbool_flag(sk, SOCK_FILTER_LOCKED, valbool);
 		break;
 
-	case SO_PASSSEC:
-		assign_bit(SOCK_PASSSEC, &sock->flags, valbool);
-		break;
 	case SO_MARK:
 		if (!sockopt_ns_capable(sock_net(sk)->user_ns, CAP_NET_RAW) &&
 		    !sockopt_ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN)) {