path: root/samples/bpf/xdp_redirect_map_user.c
diff options
authorToke Høiland-Jørgensen <>2019-12-16 12:07:42 +0100
committerAlexei Starovoitov <>2019-12-16 07:05:38 -0800
commitd50ecc46d18fa19ccf06e0c4d2ee8a050c665e3d (patch)
treeb60ffa2c725d450b8f336af5283ddc733ba8da21 /samples/bpf/xdp_redirect_map_user.c
parent450278977acbf494a20367c22fbb38729772d1fc (diff)
samples/bpf: Attach XDP programs in driver mode by default
When attaching XDP programs, userspace can set flags to request the attach mode (generic/SKB mode, driver mode or hw offloaded mode). If no such flags are requested, the kernel will attempt to attach in driver mode, and then silently fall back to SKB mode if this fails. The silent fallback is a major source of user confusion, as users will try to load a program on a device without XDP support, and instead of an error they will get the silent fallback behaviour, not notice, and then wonder why performance is not what they were expecting. In an attempt to combat this, let's switch all the samples to default to explicitly requesting driver-mode attach. As part of this, ensure that all the userspace utilities have a switch to enable SKB mode. For those that have a switch to request driver mode, keep it but turn it into a no-op. Signed-off-by: Toke Høiland-Jørgensen <> Signed-off-by: Alexei Starovoitov <> Acked-by: Jesper Dangaard Brouer <> Acked-by: David Ahern <> Link:
Diffstat (limited to 'samples/bpf/xdp_redirect_map_user.c')
1 files changed, 4 insertions, 1 deletions
diff --git a/samples/bpf/xdp_redirect_map_user.c b/samples/bpf/xdp_redirect_map_user.c
index f70ee33907fd..cc840661faab 100644
--- a/samples/bpf/xdp_redirect_map_user.c
+++ b/samples/bpf/xdp_redirect_map_user.c
@@ -116,7 +116,7 @@ int main(int argc, char **argv)
xdp_flags |= XDP_FLAGS_SKB_MODE;
case 'N':
- xdp_flags |= XDP_FLAGS_DRV_MODE;
+ /* default, set below */
case 'F':
@@ -127,6 +127,9 @@ int main(int argc, char **argv)
+ if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
+ xdp_flags |= XDP_FLAGS_DRV_MODE;
if (optind == argc) {
printf("usage: %s <IFNAME|IFINDEX>_IN <IFNAME|IFINDEX>_OUT\n", argv[0]);
return 1;