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Message-ID: <CAH3MdRXkr5oD=yTr8qevFMLBuLyv1v-E7BLme8n2FA8+uPe6sg@mail.gmail.com>
Date: Thu, 1 Aug 2019 23:23:18 -0700
From: Y Song <ys114321@...il.com>
To: "Daniel T. Lee" <danieltimlee@...il.com>
Cc: Daniel Borkmann <daniel@...earbox.net>,
Alexei Starovoitov <ast@...nel.org>,
netdev <netdev@...r.kernel.org>
Subject: Re: [v2,1/2] tools: bpftool: add net attach command to attach XDP on interface
On Thu, Aug 1, 2019 at 2:04 AM Daniel T. Lee <danieltimlee@...il.com> wrote:
>
> By this commit, using `bpftool net attach`, user can attach XDP prog on
> interface. New type of enum 'net_attach_type' has been made, as stated at
> cover-letter, the meaning of 'attach' is, prog will be attached on interface.
>
> BPF prog will be attached through libbpf 'bpf_set_link_xdp_fd'.
>
> Signed-off-by: Daniel T. Lee <danieltimlee@...il.com>
> ---
> Changes in v2:
> - command 'load' changed to 'attach' for the consistency
> - 'NET_ATTACH_TYPE_XDP_DRIVE' changed to 'NET_ATTACH_TYPE_XDP_DRIVER'
>
> tools/bpf/bpftool/net.c | 107 +++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 106 insertions(+), 1 deletion(-)
>
> diff --git a/tools/bpf/bpftool/net.c b/tools/bpf/bpftool/net.c
> index 67e99c56bc88..f3b57660b303 100644
> --- a/tools/bpf/bpftool/net.c
> +++ b/tools/bpf/bpftool/net.c
> @@ -55,6 +55,35 @@ struct bpf_attach_info {
> __u32 flow_dissector_id;
> };
>
> +enum net_attach_type {
> + NET_ATTACH_TYPE_XDP,
> + NET_ATTACH_TYPE_XDP_GENERIC,
> + NET_ATTACH_TYPE_XDP_DRIVER,
> + NET_ATTACH_TYPE_XDP_OFFLOAD,
> + __MAX_NET_ATTACH_TYPE
> +};
> +
> +static const char * const attach_type_strings[] = {
> + [NET_ATTACH_TYPE_XDP] = "xdp",
> + [NET_ATTACH_TYPE_XDP_GENERIC] = "xdpgeneric",
> + [NET_ATTACH_TYPE_XDP_DRIVER] = "xdpdrv",
> + [NET_ATTACH_TYPE_XDP_OFFLOAD] = "xdpoffload",
> + [__MAX_NET_ATTACH_TYPE] = NULL,
> +};
> +
> +static enum net_attach_type parse_attach_type(const char *str)
> +{
> + enum net_attach_type type;
> +
> + for (type = 0; type < __MAX_NET_ATTACH_TYPE; type++) {
> + if (attach_type_strings[type] &&
> + is_prefix(str, attach_type_strings[type]))
> + return type;
> + }
> +
> + return __MAX_NET_ATTACH_TYPE;
> +}
> +
> static int dump_link_nlmsg(void *cookie, void *msg, struct nlattr **tb)
> {
> struct bpf_netdev_t *netinfo = cookie;
> @@ -223,6 +252,77 @@ static int query_flow_dissector(struct bpf_attach_info *attach_info)
> return 0;
> }
>
> +static int parse_attach_args(int argc, char **argv, int *progfd,
> + enum net_attach_type *attach_type, int *ifindex)
> +{
> + if (!REQ_ARGS(3))
> + return -EINVAL;
> +
> + *progfd = prog_parse_fd(&argc, &argv);
> + if (*progfd < 0)
> + return *progfd;
> +
> + *attach_type = parse_attach_type(*argv);
> + if (*attach_type == __MAX_NET_ATTACH_TYPE) {
> + p_err("invalid net attach/detach type");
> + return -EINVAL;
> + }
> +
> + NEXT_ARG();
> + if (!REQ_ARGS(1))
> + return -EINVAL;
> +
> + *ifindex = if_nametoindex(*argv);
> + if (!*ifindex) {
> + p_err("Invalid ifname");
Do you want to use the full function name "invalid if_nametoindex" here?
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +static int do_attach_detach_xdp(int *progfd, enum net_attach_type *attach_type,
> + int *ifindex)
You can just use plain int as the argument type here.
> +{
> + __u32 flags;
> + int err;
> +
> + flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
> + if (*attach_type == NET_ATTACH_TYPE_XDP_GENERIC)
> + flags |= XDP_FLAGS_SKB_MODE;
> + if (*attach_type == NET_ATTACH_TYPE_XDP_DRIVER)
> + flags |= XDP_FLAGS_DRV_MODE;
> + if (*attach_type == NET_ATTACH_TYPE_XDP_OFFLOAD)
> + flags |= XDP_FLAGS_HW_MODE;
> +
> + err = bpf_set_link_xdp_fd(*ifindex, *progfd, flags);
> +
> + return err;
Just do "return bpf_set_link_xdp_fd(...)" and you do not need variable err.
> +}
> +
> +static int do_attach(int argc, char **argv)
> +{
> + enum net_attach_type attach_type;
> + int err, progfd, ifindex;
> +
> + err = parse_attach_args(argc, argv, &progfd, &attach_type, &ifindex);
> + if (err)
> + return err;
> +
> + if (is_prefix("xdp", attach_type_strings[attach_type]))
> + err = do_attach_detach_xdp(&progfd, &attach_type, &ifindex);
> +
> + if (err < 0) {
> + p_err("link set %s failed", attach_type_strings[attach_type]);
> + return -1;
> + }
The above "if (err < 0)" can be true only under the above "if (is_prefix(..))"
conditions. But compiler may optimize this. So I think current form is okay.
But could you change the return value to "return err" instead of "return -1"?
> +
> + if (json_output)
> + jsonw_null(json_wtr);
> +
> + return 0;
> +}
> +
> static int do_show(int argc, char **argv)
> {
> struct bpf_attach_info attach_info = {};
> @@ -305,13 +405,17 @@ static int do_help(int argc, char **argv)
>
> fprintf(stderr,
> "Usage: %s %s { show | list } [dev <devname>]\n"
> + " %s %s attach PROG LOAD_TYPE <devname>\n"
> " %s %s help\n"
> + "\n"
> + " " HELP_SPEC_PROGRAM "\n"
> + " LOAD_TYPE := { xdp | xdpgeneric | xdpdrv | xdpoffload }\n"
> "Note: Only xdp and tc attachments are supported now.\n"
> " For progs attached to cgroups, use \"bpftool cgroup\"\n"
> " to dump program attachments. For program types\n"
> " sk_{filter,skb,msg,reuseport} and lwt/seg6, please\n"
> " consult iproute2.\n",
> - bin_name, argv[-2], bin_name, argv[-2]);
> + bin_name, argv[-2], bin_name, argv[-2], bin_name, argv[-2]);
>
> return 0;
> }
> @@ -319,6 +423,7 @@ static int do_help(int argc, char **argv)
> static const struct cmd cmds[] = {
> { "show", do_show },
> { "list", do_show },
> + { "attach", do_attach },
> { "help", do_help },
> { 0 }
> };
> --
> 2.20.1
>
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