unix: Check service client for being null

For regular dumps this thing is not initialized.
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

sk-unix.c

@@ -88,6 +88,11 @@ static void show_one_unix_img(const char *act, const UnixSkEntry *e)
 		act, e->id, e->ino, e->peer, e->type, e->state, (int)e->name.len);
 }
 
+static bool service_socket(unsigned int sk_ino)
+{
+	return cr_service_client && (cr_service_client->sk_ino == sk_ino);
+}
+
 static int can_dump_unix_sk(const struct unix_sk_desc *sk)
 {
 	/*
@@ -97,7 +102,7 @@ static int can_dump_unix_sk(const struct unix_sk_desc *sk)
 	 */
 	if (sk->type != SOCK_STREAM &&
 	    sk->type != SOCK_DGRAM &&
-	    sk->peer_ino != cr_service_client->sk_ino) {
+	    !service_socket(sk->peer_ino)) {
 		pr_err("Only stream/dgram sockets for now\n");
 		return 0;
 	}
@@ -149,7 +154,7 @@ static int dump_one_unix_fd(int lfd, u32 id, const struct fd_parms *p)
 	 * Check if this socket is connected to criu service.
 	 * Dump it like closed one and mark it for restore.
 	 */
-	if (ue.peer == cr_service_client->sk_ino) {
+	if (service_socket(ue.peer)) {
 		ue.state = TCP_CLOSE;
 		ue.peer = 0;
 		ue.uflags |= USK_SERVICE;