From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roman Gushchin Subject: Re: [PATCH bpf-next 1/2] bpftool: introduce cgroup tree command Date: Fri, 6 Jul 2018 11:25:45 -0700 Message-ID: <20180706182542.GA27167@castle.DHCP.thefacebook.com> References: <20180706010521.23097-1-guro@fb.com> <20180705190116.7737d66d@cakuba.netronome.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: , , , Quentin Monnet , Daniel Borkmann , Alexei Starovoitov , David Ahern To: Jakub Kicinski Return-path: Content-Disposition: inline In-Reply-To: <20180705190116.7737d66d@cakuba.netronome.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Thu, Jul 05, 2018 at 07:01:16PM -0700, Jakub Kicinski wrote: > On Thu, 5 Jul 2018 18:05:20 -0700, Roman Gushchin wrote: > > 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 > > Cc: Jakub Kicinski > > Cc: Quentin Monnet > > Cc: Daniel Borkmann > > Cc: Alexei Starovoitov > > Looks very useful! Minor nits/questions below. I think the reverse > mapping could also be interesting - similar to how -f flag shows where > program is pinned, we could add a flag which in > > # bpftool prog show/list > > adds info about cgroups where the program is attached? Obviously as a > future extension. Well, it would be convenient, but it's not always possible. A program can be attached to a dying cgroup (a cgroup which was deleted by a user, but still has some associated resources, e.g. pagecache). > > > diff --git a/tools/bpf/bpftool/cgroup.c b/tools/bpf/bpftool/cgroup.c > > index 16bee011e16c..125d5b6db568 100644 > > --- a/tools/bpf/bpftool/cgroup.c > > +++ b/tools/bpf/bpftool/cgroup.c > > @@ -2,7 +2,12 @@ > > // Copyright (C) 2017 Facebook > > // Author: Roman Gushchin > > > > +#define _XOPEN_SOURCE 500 > > +#include > > #include > > +#include > > +#include > > +#include > > #include > > #include > > #include > > @@ -53,7 +58,8 @@ static enum bpf_attach_type parse_attach_type(const char *str) > > } > > > > static int show_bpf_prog(int id, const char *attach_type_str, > > - const char *attach_flags_str) > > + const char *attach_flags_str, > > + int level) > > { > > struct bpf_prog_info info = {}; > > __u32 info_len = sizeof(info); > > @@ -78,7 +84,8 @@ static int show_bpf_prog(int id, const char *attach_type_str, > > jsonw_string_field(json_wtr, "name", info.name); > > jsonw_end_object(json_wtr); > > } else { > > - printf("%-8u %-15s %-15s %-15s\n", info.id, > > + printf("%s%-8u %-15s %-15s %-15s\n", level ? " " : "", > > + info.id, > > attach_type_str, > > attach_flags_str, > > info.name); > > @@ -88,7 +95,20 @@ static int show_bpf_prog(int id, const char *attach_type_str, > > return 0; > > } > > > > -static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type) > > +static int count_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type) > > +{ > > + __u32 prog_cnt = 0; > > + int ret; > > + > > + ret = bpf_prog_query(cgroup_fd, type, 0, NULL, NULL, &prog_cnt); > > + if (ret) > > + return -1; > > + > > + return prog_cnt; > > +} > > + > > +static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type, > > + int level) > > { > > __u32 prog_ids[1024] = {0}; > > char *attach_flags_str; > > @@ -123,7 +143,7 @@ static int show_attached_bpf_progs(int cgroup_fd, enum bpf_attach_type type) > > > > for (iter = 0; iter < prog_cnt; iter++) > > show_bpf_prog(prog_ids[iter], attach_type_strings[type], > > - attach_flags_str); > > + attach_flags_str, level); > > > > return 0; > > } > > @@ -161,7 +181,7 @@ static int do_show(int argc, char **argv) > > * If we were able to get the show for at least one > > * attach type, let's return 0. > > */ > > - if (show_attached_bpf_progs(cgroup_fd, type) == 0) > > + if (show_attached_bpf_progs(cgroup_fd, type, 0) == 0) > > ret = 0; > > } > > > > @@ -173,6 +193,123 @@ static int do_show(int argc, char **argv) > > return ret; > > } > > > > +static int do_show_tree_fn(const char *fpath, const struct stat *sb, > > + int typeflag, struct FTW *ftw) > > +{ > > + enum bpf_attach_type type; > > + bool skip = true; > > + int cgroup_fd; > > + > > + if (typeflag != FTW_D) > > + return 0; > > + > > + cgroup_fd = open(fpath, O_RDONLY); > > + if (cgroup_fd < 0) { > > + p_err("can't open cgroup %s: %s", fpath, strerror(errno)); > > + return -1; > > + } > > + > > + for (type = 0; type < __MAX_BPF_ATTACH_TYPE; type++) { > > + int count = count_attached_bpf_progs(cgroup_fd, type); > > + > > + if (count < 0 && errno != EINVAL) { > > + p_err("can't query bpf programs attached to %s: %s", > > + fpath, strerror(errno)); > > + close(cgroup_fd); > > + return -1; > > + } > > + if (count > 0) { > > + skip = false; > > + break; > > + } > > + } > > + > > + if (skip) { > > + close(cgroup_fd); > > + return 0; > > + } > > + > > + if (json_output) { > > + jsonw_start_object(json_wtr); > > + jsonw_string_field(json_wtr, "cgroup", fpath); > > + jsonw_name(json_wtr, "programs"); > > + jsonw_start_array(json_wtr); > > + } else { > > + printf("%s\n", fpath); > > + } > > + > > + for (type = 0; type < __MAX_BPF_ATTACH_TYPE; type++) > > + show_attached_bpf_progs(cgroup_fd, type, ftw->level); > > + > > + if (json_output) { > > + jsonw_end_array(json_wtr); > > + jsonw_end_object(json_wtr); > > + } > > + > > + close(cgroup_fd); > > + > > + return 0; > > +} > > + > > +static char *find_cgroup_root(void) > > +{ > > + struct mntent *mnt; > > + FILE *f; > > + > > + f = fopen("/proc/mounts", "r"); > > + if (f == NULL) > > + return NULL; > > + > > + while ((mnt = getmntent(f))) { > > + if (strcmp(mnt->mnt_type, "cgroup2") == 0) { > > + fclose(f); > > + return strdup(mnt->mnt_dir); > > FWIW you don't free this memory. Doesn't really matter, as we do exit immediately after, but fixed in v2 anyway. > > > + } > > + } > > + > > + fclose(f); > > + return NULL; > > +} > > + > > +static int do_show_tree(int argc, char **argv) > > +{ > > + char *cgroup_root; > > + int ret; > > + > > + if (argc > 1) { > > + p_err("too many parameters for cgroup tree"); > > + return -1; > > + } > > + > > + if (argc == 1) { > > + cgroup_root = argv[0]; > > + } else { > > + cgroup_root = find_cgroup_root(); > > + > > + if (!cgroup_root) { > > + p_err("cgroup v2 isn't mounted"); > > + return -1; > > + } > > + } > > + > > + if (json_output) > > + jsonw_start_array(json_wtr); > > + else > > + printf("%s\n" > > + "%-8s %-15s %-15s %-15s\n", > > + "CgroupPath", > > + "ID", "AttachType", "AttachFlags", "Name"); > > + > > + ret = nftw(cgroup_root, do_show_tree_fn, 1024, FTW_MOUNT); > > + if (ret && errno == ENOENT) > > + p_err("can't iterate over %s: %s", cgroup_root, > > + strerror(errno)); > > I'm worried this could lead to a duplicated error in JSON output, no? > Is it possible that do_show_tree_fn() would have already printed an > error? Fixed in v2. > > > + > > + if (json_output) > > + jsonw_end_array(json_wtr); > > + > > + return ret; > > +} > > + > > static int do_attach(int argc, char **argv) > > { > > enum bpf_attach_type attach_type; > > @@ -289,6 +426,7 @@ static int do_help(int argc, char **argv) > > > > fprintf(stderr, > > "Usage: %s %s { show | list } CGROUP\n" > > + " %s %s tree [CGROUP_ROOT]\n" > > " %s %s attach CGROUP ATTACH_TYPE PROG [ATTACH_FLAGS]\n" > > " %s %s detach CGROUP ATTACH_TYPE PROG\n" > > " %s %s help\n" > > @@ -298,6 +436,7 @@ static int do_help(int argc, char **argv) > > " " HELP_SPEC_PROGRAM "\n" > > " " HELP_SPEC_OPTIONS "\n" > > "", > > + bin_name, argv[-2], > > bin_name, argv[-2], bin_name, argv[-2], > > bin_name, argv[-2], bin_name, argv[-2]); > > > > @@ -307,6 +446,7 @@ static int do_help(int argc, char **argv) > > static const struct cmd cmds[] = { > > { "show", do_show }, > > { "list", do_show }, > > + { "tree", do_show_tree }, > > { "attach", do_attach }, > > { "detach", do_detach }, > > { "help", do_help }, > > Could you please also add this new command to bash completions? It > should be fairly trivial to handle. Sure. Thanks!