// SPDX-License-Identifier: GPL-2.0-only
/*
* This test makes sure BPF stats collection using rstat works correctly.
* The test uses 3 BPF progs:
* (a) counter: This BPF prog is invoked every time we attach a process to a
* cgroup and locklessly increments a percpu counter.
* The program then calls cgroup_rstat_updated() to inform rstat
* of an update on the (cpu, cgroup) pair.
*
* (b) flusher: This BPF prog is invoked when an rstat flush is ongoing, it
* aggregates all percpu counters to a total counter, and also
* propagates the changes to the ancestor cgroups.
*
* (c) dumper: This BPF prog is a cgroup_iter. It is used to output the total
* counter of a cgroup through reading a file in userspace.
*
* The test sets up a cgroup hierarchy, and the above programs. It spawns a few
* processes in the leaf cgroups and makes sure all the counters are aggregated
* correctly.
*
* Copyright 2022 Google LLC.
*/
#include <asm-generic/errno.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <unistd.h>
#include <test_progs.h>
#include <bpf/libbpf.h>
#include <bpf/bpf.h>
#include "cgroup_helpers.h"
#include "cgroup_hierarchical_stats.skel.h"
#define PAGE_SIZE 4096
#define MB(x) (x << 20)
#define PROCESSES_PER_CGROUP 3
#define BPFFS_ROOT "/sys/fs/bpf/"
#define BPFFS_ATTACH_COUNTERS BPFFS_ROOT "attach_counters/"
#define CG_ROOT_NAME "root"
#define CG_ROOT_ID 1
#define CGROUP_PATH(p, n) {.path = p"/"n, .name = n}
static struct {
const char *path, *name;
unsigned long long id;
int fd;
} cgroups[] = {
CGROUP_PATH("/", "test"),
CGROUP_PATH("/test", "child1"),
CGROUP_PATH("/test", "child2"),
CGROUP_PATH("/test/child1", "child1_1"),
CGROUP_PATH("/test/child1", "child1_2"),
CGROUP_PATH("/test/child2", "child2_1"),
CGROUP_PATH("/test/child2", "child2_2"),
};
#define N_CGROUPS ARRAY_SIZE(cgroups)
#define N_NON_LEAF_CGROUPS 3
static int root_cgroup_fd;
static bool mounted_bpffs;
/* reads file at 'path' to 'buf', returns 0 on success. */
static int read_from_file(const char *path, char *buf, size_t size)
{
int fd, len;
fd = open(path, O_RDONLY);
if (fd < 0)
return fd;
len = read(fd, buf, size);
close(fd);
if (len < 0)
return len;
buf[len] = 0;
return 0;
}
/* mounts bpffs and mkdir for reading stats, returns 0 on success. */
static int setup_bpffs(void)
{
int err;
/* Mount bpffs */
err = mount("bpf", BPFFS_ROOT, "bpf", 0, NULL);
mounted_bpffs = !err;
if (ASSERT_FALSE(err && errno != EBUSY, "mount"))
return err;
/* Create a directory to contain stat files in bpffs */
err = mkdir(BPFFS_ATTACH_COUNTERS, 0755);
if (!ASSERT_OK(err, "mkdir"))
return err;
return 0;
}
static void cleanup_bpffs(void)
{
/* Remove created directory in bpffs */
ASSERT_OK(rmdir(BPFFS_ATTACH_COUNTERS), "rmdir "BPFFS_ATTACH_COUNTERS);
/* Unmount bpffs, if it wasn't already mounted when we started */
if (mounted_bpffs)
return;
ASSERT_OK(umount(BPFFS_ROOT), "unmount bpffs");
}
/* sets up cgroups, returns 0 on success. */
static int setup_cgroups(void)
{
int i, fd, err;
err = setup_cgroup_environment();
if (!ASSERT_OK(err, "setup_cgroup_environment"))
return err;
root_cgroup_fd = get_root_cgroup();
if (!ASSERT_GE(root_cgroup_fd, 0, "get_root_cgroup"))
return root_cgroup_fd;
for (i = 0; i < N_CGROUPS; i++) {
fd = create_and_get_cgroup(cgroups[i].path);
if (!ASSERT_GE(fd, 0, "create_and_get_cgroup"))
return fd;
cgroups[i].fd = fd;
cgroups[i].id = get_cgroup_id(cgroups[i].path);
}
return 0;
}
static void cleanup_cgroups(void)
{
close(root_cgroup_fd);
for (int i = 0; i < N_CGROUPS; i++)
close(cgroups[i].fd);
cleanup_cgroup_environment();
}
/* Sets up cgroup hiearchary, returns 0 on success. */
static int setup_hierarchy(void)
{
return setup_bpffs() || setup_cgroups();
}
static void destroy_hierarchy(void)
{
cleanup_cgroups();
cleanup_bpffs();
}
static int attach_processes(void)
{
int i, j, status;
/* In every leaf cgroup, attach 3 processes */
for (i = N_NON_LEAF_CGROUPS; i < N_CGROUPS; i++) {
for (j = 0; j < PROCESSES_PER_CGROUP; j++) {
pid_t pid;
/* Create child and attach to cgroup */
pid = fork();
if (pid == 0) {
if (join_parent_cgroup(cgroups[i].path))
exit(EACCES);
exit(0);
}
/* Cleanup child */
waitpid(pid, &status, 0);
if (!ASSERT_TRUE(WIFEXITED(status), "child process exited"))
return 1;
if (!ASSERT_EQ(WEXITSTATUS(status), 0,
"child process exit code"))
return 1;
}
}
return 0;
}
static unsigned long long
get_attach_counter(unsigned long long cgroup_id, const char *file_name)
{
unsigned long long attach_counter = 0, id = 0;
static char buf[128], path[128];
/* For every cgroup, read the file generated by cgroup_iter */
snprintf(path, 128, "%s%s", BPFFS_ATTACH_COUNTERS, file_name);
if (!ASSERT_OK(read_from_file(path, buf, 128), "read cgroup_iter"))
return 0;
/* Check the output file formatting */
ASSERT_EQ(sscanf(buf, "cg_id: %llu, attach_counter: %llu\n",
&id, &attach_counter), 2, "output format");
/* Check that the cgroup_id is displayed correctly */
ASSERT_EQ(id, cgroup_id, "cgroup_id");
/* Check that the counter is non-zero */
ASSERT_GT(attach_counter, 0, "attach counter non-zero");
return attach_counter;
}
static void check_attach_counters(void)
{
unsigned long long attach_counters[N_CGROUPS], root_attach_counter;
int i;
for (i = 0; i < N_CGROUPS; i++)
attach_counters[i] = get_attach_counter(cgroups[i].id,
cgroups[i].name);
/* Read stats for root too */
root_attach_counter = get_attach_counter(CG_ROOT_ID, CG_ROOT_NAME);
/* Check that all leafs cgroups have an attach counter of 3 */
for (i = N_NON_LEAF_CGROUPS; i < N_CGROUPS; i++)
ASSERT_EQ(attach_counters[i], PROCESSES_PER_CGROUP,
"leaf cgroup attach counter");
/* Check that child1 == child1_1 + child1_2 */
ASSERT_EQ(attach_counters[1], attach_counters[3] + attach_counters[4],
"child1_counter");
/* Check that child2 == child2_1 + child2_2 */
ASSERT_EQ(attach_counters[2], attach_counters[5] + attach_counters[6],
"child2_counter");
/* Check that test == child1 + child2 */
ASSERT_EQ(attach_counters[0], attach_counters[1] + attach_counters[2],
"test_counter");
/* Check that root >= test */
ASSERT_GE(root_attach_counter, attach_counters[1], "root_counter");
}
/* Creates iter link and pins in bpffs, returns 0 on success, -errno on failure.
*/
static int setup_cgroup_iter(struct cgroup_hierarchical_stats *obj,
int cgroup_fd, const char *file_name)
{
DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts);
union bpf_iter_link_info linfo = {};
struct bpf_link *link;
static char path[128];
int err;
/*
* Create an iter link, parameterized by cgroup_fd. We only want to
* traverse one cgroup, so set the traversal order to "self".
*/
linfo.cgroup.cgroup_fd = cgroup_fd;
linfo.cgroup.order = BPF_CGROUP_ITER_SELF_ONLY;
opts.link_info = &linfo;
opts.link_info_len = sizeof(linfo);
link = bpf_program__attach_iter(obj->progs.dumper, &opts);
if (!ASSERT_OK_PTR(link, "attach_iter"))
return -EFAULT;
/* Pin the link to a bpffs file */
snprintf(path, 128, "%s%s", BPFFS_ATTACH_COUNTERS, file_name);
err = bpf_link__pin(link, path);
ASSERT_OK(err, "pin cgroup_iter");
/* Remove the link, leaving only the ref held by the pinned file */
bpf_link__destroy(link);
return err;
}
/* Sets up programs for collecting stats, returns 0 on success. */
static int setup_progs(struct cgroup_hierarchical_stats **skel)
{
int i, err;
*skel = cgroup_hierarchical_stats__open_and_load();
if (!ASSERT_OK_PTR(*skel, "open_and_load"))
return 1;
/* Attach cgroup_iter program that will dump the stats to cgroups */
for (i = 0; i < N_CGROUPS; i++) {
err = setup_cgroup_iter(*skel, cgroups[i].fd, cgroups[i].name);
if (!ASSERT_OK(err, "setup_cgroup_iter"))
return err;
}
/* Also dump stats for root */
err = setup_cgroup_iter(*skel, root_cgroup_fd, CG_ROOT_NAME);
if (!ASSERT_OK(err, "setup_cgroup_iter"))
return err;
bpf_program__set_autoattach((*skel)->progs.dumper, false);
err = cgroup_hierarchical_stats__attach(*skel);
if (!ASSERT_OK(err, "attach"))
return err;
return 0;
}
static void destroy_progs(struct cgroup_hierarchical_stats *skel)
{
static char path[128];
int i;
for (i = 0; i < N_CGROUPS; i++) {
/* Delete files in bpffs that cgroup_iters are pinned in */
snprintf(path, 128, "%s%s", BPFFS_ATTACH_COUNTERS,
cgroups[i].name);
ASSERT_OK(remove(path), "remove cgroup_iter pin");
}
/* Delete root file in bpffs */
snprintf(path, 128, "%s%s", BPFFS_ATTACH_COUNTERS, CG_ROOT_NAME);
ASSERT_OK(remove(path), "remove cgroup_iter root pin");
cgroup_hierarchical_stats__destroy(skel);
}
void test_cgroup_hierarchical_stats(void)
{
struct cgroup_hierarchical_stats *skel = NULL;
if (setup_hierarchy())
goto hierarchy_cleanup;
if (setup_progs(&skel))
goto cleanup;
if (attach_processes())
goto cleanup;
check_attach_counters();
cleanup:
destroy_progs(skel);
hierarchy_cleanup:
destroy_hierarchy();
}
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