forked from Minki/linux
bpftool: introduce cgroup tree command
This commit introduces a new bpftool command: cgroup tree.
The idea is to iterate over the whole cgroup tree and print
all attached programs.
I was debugging a bpf/systemd issue, and found, that there is
no simple way to listen all bpf programs attached to cgroups.
I did master something in bash, but after some time got tired of it,
and decided, that adding a dedicated bpftool command could be
a better idea.
So, here it is:
$ sudo ./bpftool cgroup tree
CgroupPath
ID AttachType AttachFlags Name
/sys/fs/cgroup/system.slice/systemd-machined.service
18 ingress
17 egress
/sys/fs/cgroup/system.slice/systemd-logind.service
20 ingress
19 egress
/sys/fs/cgroup/system.slice/systemd-udevd.service
16 ingress
15 egress
/sys/fs/cgroup/system.slice/systemd-journald.service
14 ingress
13 egress
Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Cc: Quentin Monnet <quentin.monnet@netronome.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Roman Gushchin
Daniel Borkmann
parent
ab8565af68
commit
2058b38371
@ -2,7 +2,12 @@
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// Copyright (C) 2017 Facebook
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// Author: Roman Gushchin <guro@fb.com>
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#define _XOPEN_SOURCE 500
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#include <errno.h>
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#include <fcntl.h>
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#include <ftw.h>
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#include <mntent.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/stat.h>
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@ -53,7 +58,8 @@ static enum bpf_attach_type parse_attach_type(const char *str)
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}
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static int show_bpf_prog(int id, const char *attach_type_str,
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const char *attach_flags_str)
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const char *attach_flags_str,
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int level)
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{
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struct bpf_prog_info info = {};
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__u32 info_len = sizeof(info);
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@ -78,7 +84,8 @@ static int show_bpf_prog(int id, const char *attach_type_str,
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jsonw_string_field(json_wtr, "name", info.name);
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jsonw_end_object(json_wtr);
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} else {
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printf("%-8u %-15s %-15s %-15s\n", info.id,
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printf("%s%-8u %-15s %-15s %-15s\n", level ? " " : "",
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info.id,
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attach_type_str,
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attach_flags_str,
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info.name);
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@ -88,7 +95,20 @@ static int show_bpf_prog(int id, const char *attach_type_str,
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return 0;
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}
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static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type)
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static int count_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type)
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{
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__u32 prog_cnt = 0;
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int ret;
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ret = bpf_prog_query(cgroup_fd, type, 0, NULL, NULL, &prog_cnt);
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if (ret)
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return -1;
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return prog_cnt;
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}
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static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type,
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int level)
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{
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__u32 prog_ids[1024] = {0};
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char *attach_flags_str;
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@ -123,7 +143,7 @@ static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type)
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for (iter = 0; iter < prog_cnt; iter++)
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show_bpf_prog(prog_ids[iter], attach_type_strings[type],
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attach_flags_str);
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attach_flags_str, level);
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return 0;
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}
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@ -161,7 +181,7 @@ static int do_show(int argc, char **argv)
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* If we were able to get the show for at least one
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* attach type, let's return 0.
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*/
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if (show_attached_bpf_progs(cgroup_fd, type) == 0)
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if (show_attached_bpf_progs(cgroup_fd, type, 0) == 0)
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ret = 0;
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}
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@ -173,6 +193,143 @@ exit:
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return ret;
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}
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/*
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* To distinguish nftw() errors and do_show_tree_fn() errors
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* and avoid duplicating error messages, let's return -2
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* from do_show_tree_fn() in case of error.
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*/
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#define NFTW_ERR -1
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#define SHOW_TREE_FN_ERR -2
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static int do_show_tree_fn(const char *fpath, const struct stat *sb,
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int typeflag, struct FTW *ftw)
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{
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enum bpf_attach_type type;
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bool skip = true;
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int cgroup_fd;
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if (typeflag != FTW_D)
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return 0;
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cgroup_fd = open(fpath, O_RDONLY);
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if (cgroup_fd < 0) {
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p_err("can't open cgroup %s: %s", fpath, strerror(errno));
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return SHOW_TREE_FN_ERR;
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}
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for (type = 0; type < __MAX_BPF_ATTACH_TYPE; type++) {
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int count = count_attached_bpf_progs(cgroup_fd, type);
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if (count < 0 && errno != EINVAL) {
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p_err("can't query bpf programs attached to %s: %s",
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fpath, strerror(errno));
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close(cgroup_fd);
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return SHOW_TREE_FN_ERR;
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}
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if (count > 0) {
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skip = false;
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break;
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}
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}
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if (skip) {
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close(cgroup_fd);
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return 0;
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}
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if (json_output) {
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jsonw_start_object(json_wtr);
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jsonw_string_field(json_wtr, "cgroup", fpath);
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jsonw_name(json_wtr, "programs");
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jsonw_start_array(json_wtr);
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} else {
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printf("%s\n", fpath);
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}
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for (type = 0; type < __MAX_BPF_ATTACH_TYPE; type++)
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show_attached_bpf_progs(cgroup_fd, type, ftw->level);
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if (json_output) {
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jsonw_end_array(json_wtr);
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jsonw_end_object(json_wtr);
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}
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close(cgroup_fd);
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return 0;
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}
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static char *find_cgroup_root(void)
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{
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struct mntent *mnt;
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FILE *f;
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f = fopen("/proc/mounts", "r");
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if (f == NULL)
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return NULL;
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while ((mnt = getmntent(f))) {
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if (strcmp(mnt->mnt_type, "cgroup2") == 0) {
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fclose(f);
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return strdup(mnt->mnt_dir);
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}
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}
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fclose(f);
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return NULL;
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}
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static int do_show_tree(int argc, char **argv)
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{
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char *cgroup_root;
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int ret;
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switch (argc) {
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case 0:
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cgroup_root = find_cgroup_root();
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if (!cgroup_root) {
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p_err("cgroup v2 isn't mounted");
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return -1;
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}
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break;
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case 1:
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cgroup_root = argv[0];
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break;
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default:
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p_err("too many parameters for cgroup tree");
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return -1;
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}
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if (json_output)
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jsonw_start_array(json_wtr);
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else
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printf("%s\n"
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"%-8s %-15s %-15s %-15s\n",
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"CgroupPath",
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"ID", "AttachType", "AttachFlags", "Name");
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switch (nftw(cgroup_root, do_show_tree_fn, 1024, FTW_MOUNT)) {
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case NFTW_ERR:
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p_err("can't iterate over %s: %s", cgroup_root,
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strerror(errno));
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ret = -1;
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break;
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case SHOW_TREE_FN_ERR:
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ret = -1;
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break;
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default:
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ret = 0;
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}
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if (json_output)
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jsonw_end_array(json_wtr);
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if (argc == 0)
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free(cgroup_root);
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return ret;
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}
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static int do_attach(int argc, char **argv)
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{
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enum bpf_attach_type attach_type;
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@ -289,6 +446,7 @@ static int do_help(int argc, char **argv)
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fprintf(stderr,
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"Usage: %s %s { show | list } CGROUP\n"
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" %s %s tree [CGROUP_ROOT]\n"
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" %s %s attach CGROUP ATTACH_TYPE PROG [ATTACH_FLAGS]\n"
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" %s %s detach CGROUP ATTACH_TYPE PROG\n"
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" %s %s help\n"
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@ -298,6 +456,7 @@ static int do_help(int argc, char **argv)
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" " HELP_SPEC_PROGRAM "\n"
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" " HELP_SPEC_OPTIONS "\n"
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"",
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bin_name, argv[-2],
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bin_name, argv[-2], bin_name, argv[-2],
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bin_name, argv[-2], bin_name, argv[-2]);
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@ -307,6 +466,7 @@ static int do_help(int argc, char **argv)
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static const struct cmd cmds[] = {
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{ "show", do_show },
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{ "list", do_show },
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{ "tree", do_show_tree },
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{ "attach", do_attach },
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{ "detach", do_detach },
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{ "help", do_help },
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