From: Lawrence Brakmo <brakmo@fb.com>
Date: Fri, 10 Nov 2017 22:19:51 -0800
Subject: bpf: Fix tcp_rwnd_kern.c sample program
Patch-mainline: v4.15-rc1
Git-commit: 016e661bb0610a98b1c9ac1250e3269236fabe19
References: bsc#1109837

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>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 samples/bpf/tcp_rwnd_kern.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/samples/bpf/tcp_rwnd_kern.c
+++ b/samples/bpf/tcp_rwnd_kern.c
@@ -38,8 +38,10 @@ int bpf_rwnd(struct bpf_sock_ops *skops)
 	 * if neither port numberis 55601
 	 */
 	if (bpf_ntohl(skops->remote_port) !=
-	    55601 && skops->local_port != 55601)
-		return -1;
+	    55601 && skops->local_port != 55601) {
+		skops->reply = -1;
+		return 1;
+	}
 
 	op = (int) skops->op;