commit 743e568c15860d4061202f73214c106a5bb0890b
author Maciej Fijalkowski <maciejromanfijalkowski@gmail.com> Fri Feb 01 22:42:28 2019 +0100
committer Daniel Borkmann <daniel@iogearbox.net> Fri Feb 01 23:37:51 2019 +0100
tree f9970c7cb340abbc687848b8e5cfeb7db8da22bf
parent 01dde20ce04b3a18f1e91d6d1ee0ef484d20bbf2

samples/bpf: Add a "force" flag to XDP samples

Make xdp samples consistent with iproute2 behavior and set the
XDP_FLAGS_UPDATE_IF_NOEXIST by default when setting the xdp program on
interface. Provide an option for user to force the program loading,
which as a result will not include the mentioned flag in
bpf_set_link_xdp_fd call.

Signed-off-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Reviewed-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

samples/bpf/xdp1_user.c

diff --git a/samples/bpf/xdp1_user.c b/samples/bpf/xdp1_user.c
index 8bfda95..505bce20 100644
--- a/samples/bpf/xdp1_user.c
+++ b/samples/bpf/xdp1_user.c
@@ -22,7 +22,7 @@
 #include "bpf/libbpf.h"
 
 static int ifindex;
-static __u32 xdp_flags;
+static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
 
 static void int_exit(int sig)
 {
@@ -63,7 +63,8 @@ static void usage(const char *prog)
 		"usage: %s [OPTS] IFACE\n\n"
 		"OPTS:\n"
 		"    -S    use skb-mode\n"
-		"    -N    enforce native mode\n",
+		"    -N    enforce native mode\n"
+		"    -F    force loading prog\n",
 		prog);
 }
 
@@ -73,7 +74,7 @@ int main(int argc, char **argv)
 	struct bpf_prog_load_attr prog_load_attr = {
 		.prog_type	= BPF_PROG_TYPE_XDP,
 	};
-	const char *optstr = "SN";
+	const char *optstr = "FSN";
 	int prog_fd, map_fd, opt;
 	struct bpf_object *obj;
 	struct bpf_map *map;
@@ -87,6 +88,9 @@ int main(int argc, char **argv)
 		case 'N':
 			xdp_flags |= XDP_FLAGS_DRV_MODE;
 			break;
+		case 'F':
+			xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
+			break;
 		default:
 			usage(basename(argv[0]));
 			return 1;