1 files changed, 22 insertions, 11 deletions

diff --git a/tools/testing/selftests/net/mptcp/pm_nl_ctl.c b/tools/testing/selftests/net/mptcp/pm_nl_ctl.c
index 1887bd61bd9a..49369c4a5f26 100644
--- a/tools/testing/selftests/net/mptcp/pm_nl_ctl.c
+++ b/tools/testing/selftests/net/mptcp/pm_nl_ctl.c
@@ -66,20 +66,25 @@ static int init_genl_req(char *data, int family, int cmd, int version)
 	return off;
 }
 
-static void nl_error(struct nlmsghdr *nh)
+static int nl_error(struct nlmsghdr *nh)
 {
 	struct nlmsgerr *err = (struct nlmsgerr *)NLMSG_DATA(nh);
 	int len = nh->nlmsg_len - sizeof(*nh);
 	uint32_t off;
 
-	if (len < sizeof(struct nlmsgerr))
+	if (len < sizeof(struct nlmsgerr)) {
 		error(1, 0, "netlink error message truncated %d min %ld", len,
 		      sizeof(struct nlmsgerr));
+		return -1;
+	}
 
-	if (!err->error) {
+	if (err->error) {
 		/* check messages from kernel */
 		struct rtattr *attrs = (struct rtattr *)NLMSG_DATA(nh);
 
+		fprintf(stderr, "netlink error %d (%s)\n",
+			err->error, strerror(-err->error));
+
 		while (RTA_OK(attrs, len)) {
 			if (attrs->rta_type == NLMSGERR_ATTR_MSG)
 				fprintf(stderr, "netlink ext ack msg: %s\n",
@@ -91,9 +96,10 @@ static void nl_error(struct nlmsghdr *nh)
 			}
 			attrs = RTA_NEXT(attrs, len);
 		}
-	} else {
-		fprintf(stderr, "netlink error %d", err->error);
+		return -1;
 	}
+
+	return 0;
 }
 
 static int capture_events(int fd, int event_group)
@@ -198,7 +204,7 @@ static int capture_events(int fd, int event_group)
 	return 0;
 }
 
-/* do a netlink command and, if max > 0, fetch the reply  */
+/* do a netlink command and, if max > 0, fetch the reply ; nh's size >1024B */
 static int do_nl_req(int fd, struct nlmsghdr *nh, int len, int max)
 {
 	struct sockaddr_nl nladdr = { .nl_family = AF_NETLINK };
@@ -207,12 +213,16 @@ static int do_nl_req(int fd, struct nlmsghdr *nh, int len, int max)
 	int rem, ret;
 	int err = 0;
 
+	/* If no expected answer, ask for an ACK to look for errors if any */
+	if (max == 0) {
+		nh->nlmsg_flags |= NLM_F_ACK;
+		max = 1024;
+	}
+
 	nh->nlmsg_len = len;
 	ret = sendto(fd, data, len, 0, (void *)&nladdr, sizeof(nladdr));
 	if (ret != len)
 		error(1, errno, "send netlink: %uB != %uB\n", ret, len);
-	if (max == 0)
-		return 0;
 
 	addr_len = sizeof(nladdr);
 	rem = ret = recvfrom(fd, data, max, 0, (void *)&nladdr, &addr_len);
@@ -221,10 +231,11 @@ static int do_nl_req(int fd, struct nlmsghdr *nh, int len, int max)
 
 	/* Beware: the NLMSG_NEXT macro updates the 'rem' argument */
 	for (; NLMSG_OK(nh, rem); nh = NLMSG_NEXT(nh, rem)) {
-		if (nh->nlmsg_type == NLMSG_ERROR) {
-			nl_error(nh);
+		if (nh->nlmsg_type == NLMSG_DONE)
+			break;
+
+		if (nh->nlmsg_type == NLMSG_ERROR && nl_error(nh))
 			err = 1;
-		}
 	}
 	if (err)
 		error(1, 0, "bailing out due to netlink error[s]");