2023-05-11 17:13 UTC+0200 ~ Larysa Zaremba <larysa.zaremba@xxxxxxxxx>
> Add ability to specify a network interface used to resolve
> XDP Hints kfuncs when loading program through bpftool.
>
> Usage:
> bpftool prog load <bpf_obj_path> <pin_path> dev xdpmeta <ifname>
Thanks for this patch!
Regarding the command-line syntax, I'm not a big fan of the optional
sub-keyword for the device for XDP hints. I must admit I had not
anticipated other another use for the "dev" keyword. Instead, have you
considered one of the following:
1) Adding a different keyword ("xdpmeta_dev"?) and making it
incompatible with "dev"
2) Another alternative would be adding a sub-keyword for offload too:
bpftool p l [...] dev <[offload <ifname> | xdpmeta <ifname>]>
If the ifname is provided with no sub-keyword, we would consider it for
offload for legacy support, possibly warn that the syntax is deprecated.
What do you think?
>
> Signed-off-by: Larysa Zaremba <larysa.zaremba@xxxxxxxxx>
> ---
> tools/bpf/bpftool/prog.c | 28 +++++++++++++++++++++-------
> 1 file changed, 21 insertions(+), 7 deletions(-)
>
> diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
> index 91b6075b2db3..a9cb96d99277 100644
> --- a/tools/bpf/bpftool/prog.c
> +++ b/tools/bpf/bpftool/prog.c
> @@ -1517,12 +1517,13 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
> struct bpf_program *prog = NULL, *pos;
> unsigned int old_map_fds = 0;
> const char *pinmaps = NULL;
> + __u32 offload_ifindex = 0;
> bool auto_attach = false;
> + __u32 meta_ifindex = 0;
> struct bpf_object *obj;
> struct bpf_map *map;
> const char *pinfile;
> unsigned int i, j;
> - __u32 ifindex = 0;
> const char *file;
> int idx, err;
>
> @@ -1614,17 +1615,25 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
> map_replace[old_map_fds].fd = fd;
> old_map_fds++;
> } else if (is_prefix(*argv, "dev")) {
> + __u32 *cur_ifindex;
> +
> NEXT_ARG();
>
> - if (ifindex) {
> - p_err("offload device already specified");
> + if (offload_ifindex || meta_ifindex) {
> + p_err("device already specified");
I'd add a note to tell somehow that offload and XDP hints are mutually
exclusive. I suspect not all users understand these well.
> goto err_free_reuse_maps;
> }
> + if (is_prefix(*argv, "xdpmeta")) {
> + cur_ifindex = &meta_ifindex;
> + NEXT_ARG();
> + } else {
> + cur_ifindex = &offload_ifindex;
> + }
> if (!REQ_ARGS(1))
> goto err_free_reuse_maps;
>
> - ifindex = if_nametoindex(*argv);
> - if (!ifindex) {
> + *cur_ifindex = if_nametoindex(*argv);
> + if (!(*cur_ifindex)) {
> p_err("unrecognized netdevice '%s': %s",
> *argv, strerror(errno));
> goto err_free_reuse_maps;
> @@ -1671,7 +1680,12 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
> goto err_close_obj;
> }
>
> - bpf_program__set_ifindex(pos, ifindex);
> + if (prog_type == BPF_PROG_TYPE_XDP && meta_ifindex) {
> + bpf_program__set_flags(pos, BPF_F_XDP_DEV_BOUND_ONLY);
> + bpf_program__set_ifindex(pos, meta_ifindex);
> + } else {
> + bpf_program__set_ifindex(pos, offload_ifindex);
> + }
> if (bpf_program__type(pos) != prog_type)
> bpf_program__set_type(pos, prog_type);
> bpf_program__set_expected_attach_type(pos, expected_attach_type);
> @@ -1709,7 +1723,7 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
> idx = 0;
> bpf_object__for_each_map(map, obj) {
> if (bpf_map__type(map) != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
> - bpf_map__set_ifindex(map, ifindex);
> + bpf_map__set_ifindex(map, offload_ifindex);
>
> if (j < old_map_fds && idx == map_replace[j].idx) {
> err = bpf_map__reuse_fd(map, map_replace[j++].fd);
Could you please also update the following items:
- The usage message for "bpftool prog load" near the end of prog.c
- The related doc in Documentation/bpftool-prog.rst (command summary
near the top, and detailed description later in the doc)
- Bash completion (for keyword "dev", look for "_sysfs_get_netdevs" in
bash-completion/bpftool). I'm happy to help with this one if necessary.
Thanks,
Quentin
