bpf: Fix tcp_bufs_kern.c sample program

The program was returning -1 in some cases which is not allowed
by the verifier any longer.

Fixes: 390ee7e29fc8 ("bpf: enforce return code for cgroup-bpf programs")
Signed-off-by: Lawrence Brakmo <brakmo@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

samples/bpf/tcp_bufs_kern.c

@@ -41,8 +41,10 @@ int bpf_bufs(struct bpf_sock_ops *skops)
 	 * if neither port numberis 55601
 	 */
 	if (bpf_ntohl(skops->remote_port) != 55601 &&
-	    skops->local_port != 55601)
-		return -1;
+	    skops->local_port != 55601) {
+		skops->reply = -1;
+		return 1;
+	}
 
 	op = (int) skops->op;
 
@@ -61,8 +63,8 @@ int bpf_bufs(struct bpf_sock_ops *skops)
 		/* Set sndbuf and rcvbuf of active connections */
 		rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize,
 				    sizeof(bufsize));
-		rv = rv*100 + bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF,
-					     &bufsize, sizeof(bufsize));
+		rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF,
+				     &bufsize, sizeof(bufsize));
 		break;
 	case BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB:
 		/* Nothing to do */
@@ -71,8 +73,8 @@ int bpf_bufs(struct bpf_sock_ops *skops)
 		/* Set sndbuf and rcvbuf of passive connections */
 		rv = bpf_setsockopt(skops, SOL_SOCKET, SO_SNDBUF, &bufsize,
 				    sizeof(bufsize));
-		rv = rv*100 + bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF,
-					     &bufsize, sizeof(bufsize));
+		rv += bpf_setsockopt(skops, SOL_SOCKET, SO_RCVBUF,
+				     &bufsize, sizeof(bufsize));
 		break;
 	default:
 		rv = -1;