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 <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Quentin Monnet <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
---
tools/bpf/bpftool/cgroup.c | 150 +++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 145 insertions(+), 5 deletions(-)
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 <[email protected]>
+#define _XOPEN_SOURCE 500
+#include <errno.h>
#include <fcntl.h>
+#include <ftw.h>
+#include <mntent.h>
+#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
@@ -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);
+ }
+ }
+
+ 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));
+
+ 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 },
--
2.14.4
Describe cgroup tree command in the corresponding bpftool man page.
Signed-off-by: Roman Gushchin <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Quentin Monnet <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
---
tools/bpf/bpftool/Documentation/bpftool-cgroup.rst | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst b/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst
index 7b0e6d453e92..3b3d6c534317 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-cgroup.rst
@@ -21,6 +21,7 @@ MAP COMMANDS
=============
| **bpftool** **cgroup { show | list }** *CGROUP*
+| **bpftool** **cgroup tree** [*CGROUP_ROOT*]
| **bpftool** **cgroup attach** *CGROUP* *ATTACH_TYPE* *PROG* [*ATTACH_FLAGS*]
| **bpftool** **cgroup detach** *CGROUP* *ATTACH_TYPE* *PROG*
| **bpftool** **cgroup help**
@@ -39,6 +40,15 @@ DESCRIPTION
Output will start with program ID followed by attach type,
attach flags and program name.
+ **bpftool cgroup tree** [*CGROUP_ROOT*]
+ Iterate over all cgroups in *CGROUP_ROOT* and list all
+ attached programs. If *CGROUP_ROOT* is not specified,
+ bpftool uses cgroup v2 mountpoint.
+
+ The output is similar to the output of cgroup show/list
+ commands: it starts with absolute cgroup path, followed by
+ program ID, attach type, attach flags and program name.
+
**bpftool cgroup attach** *CGROUP* *ATTACH_TYPE* *PROG* [*ATTACH_FLAGS*]
Attach program *PROG* to the cgroup *CGROUP* with attach type
*ATTACH_TYPE* and optional *ATTACH_FLAGS*.
--
2.14.4
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 <[email protected]>
> Cc: Jakub Kicinski <[email protected]>
> Cc: Quentin Monnet <[email protected]>
> Cc: Daniel Borkmann <[email protected]>
> Cc: Alexei Starovoitov <[email protected]>
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.
> 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 <[email protected]>
>
> +#define _XOPEN_SOURCE 500
> +#include <errno.h>
> #include <fcntl.h>
> +#include <ftw.h>
> +#include <mntent.h>
> +#include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
> #include <sys/stat.h>
> @@ -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.
> + }
> + }
> +
> + 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?
> +
> + 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.
On Thu, 5 Jul 2018 18:05:21 -0700, Roman Gushchin wrote:
> Describe cgroup tree command in the corresponding bpftool man page.
>
> Signed-off-by: Roman Gushchin <[email protected]>
> Cc: Jakub Kicinski <[email protected]>
> Cc: Quentin Monnet <[email protected]>
> Cc: Daniel Borkmann <[email protected]>
> Cc: Alexei Starovoitov <[email protected]>
Acked-by: Jakub Kicinski <[email protected]>
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 <[email protected]>
> > Cc: Jakub Kicinski <[email protected]>
> > Cc: Quentin Monnet <[email protected]>
> > Cc: Daniel Borkmann <[email protected]>
> > Cc: Alexei Starovoitov <[email protected]>
>
> 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 <[email protected]>
> >
> > +#define _XOPEN_SOURCE 500
> > +#include <errno.h>
> > #include <fcntl.h>
> > +#include <ftw.h>
> > +#include <mntent.h>
> > +#include <stdio.h>
> > #include <stdlib.h>
> > #include <string.h>
> > #include <sys/stat.h>
> > @@ -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!
On Fri, 6 Jul 2018 11:25:45 -0700, Roman Gushchin wrote:
> > 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).
Ack, the bpffs and cgroupfs searches are best effort by definition.
Thanks for addressing the other comments!