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selftests/bpf: Add tests for css_task iter combining with cgroup iter

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This patch adds a test which demonstrates how css_task iter can be combined
with cgroup iter and it won't cause deadlock, though cgroup iter is not
sleepable.

Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20231031050438.93297-3-zhouchuyi@bytedance.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Chuyi Zhou 2023-10-31 13:04:37 +08:00 • committed by Alexei Starovoitov
parent 3091b66749
commit f49843afde
2 changed files with 77 additions and 0 deletions
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33
tools/testing/selftests/bpf/prog_tests/cgroup_iter.c
View file

@ -4,6 +4,7 @@
#include <test_progs.h>
#include <bpf/libbpf.h>
#include <bpf/btf.h>
#include "iters_css_task.skel.h"
#include "cgroup_iter.skel.h"
#include "cgroup_helpers.h"
@ -263,6 +264,35 @@ close_cgrp:
close(cgrp_fd);
}
static void test_walk_self_only_css_task(void)
{
struct iters_css_task *skel;
int err;
skel = iters_css_task__open();
if (!ASSERT_OK_PTR(skel, "skel_open"))
return;
bpf_program__set_autoload(skel->progs.cgroup_id_printer, true);
err = iters_css_task__load(skel);
if (!ASSERT_OK(err, "skel_load"))
goto cleanup;
err = join_cgroup(cg_path[CHILD2]);
if (!ASSERT_OK(err, "join_cgroup"))
goto cleanup;
skel->bss->target_pid = getpid();
snprintf(expected_output, sizeof(expected_output),
PROLOGUE "%8llu\n" EPILOGUE, cg_id[CHILD2]);
read_from_cgroup_iter(skel->progs.cgroup_id_printer, cg_fd[CHILD2],
BPF_CGROUP_ITER_SELF_ONLY, "test_walk_self_only_css_task");
ASSERT_EQ(skel->bss->css_task_cnt, 1, "css_task_cnt");
cleanup:
iters_css_task__destroy(skel);
}
void test_cgroup_iter(void)
{
struct cgroup_iter *skel = NULL;
@ -293,6 +323,9 @@ void test_cgroup_iter(void)
test_walk_self_only(skel);
if (test__start_subtest("cgroup_iter__dead_self_only"))
test_walk_dead_self_only(skel);
if (test__start_subtest("cgroup_iter__self_only_css_task"))
test_walk_self_only_css_task();
out:
cgroup_iter__destroy(skel);
cleanup_cgroups();

44
tools/testing/selftests/bpf/progs/iters_css_task.c
View file

@ -10,6 +10,7 @@
char _license[] SEC("license") = "GPL";
struct cgroup *bpf_cgroup_acquire(struct cgroup *p) __ksym;
struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
void bpf_cgroup_release(struct cgroup *p) __ksym;
@ -45,3 +46,46 @@ int BPF_PROG(iter_css_task_for_each, struct vm_area_struct *vma,
return -EPERM;
}
static inline u64 cgroup_id(struct cgroup *cgrp)
{
return cgrp->kn->id;
}
SEC("?iter/cgroup")
int cgroup_id_printer(struct bpf_iter__cgroup *ctx)
{
struct seq_file *seq = ctx->meta->seq;
struct cgroup *cgrp, *acquired;
struct cgroup_subsys_state *css;
struct task_struct *task;
u64 cgrp_id;
cgrp = ctx->cgroup;
/* epilogue */
if (cgrp == NULL) {
BPF_SEQ_PRINTF(seq, "epilogue\n");
return 0;
}
/* prologue */
if (ctx->meta->seq_num == 0)
BPF_SEQ_PRINTF(seq, "prologue\n");
cgrp_id = cgroup_id(cgrp);
BPF_SEQ_PRINTF(seq, "%8llu\n", cgrp_id);
acquired = bpf_cgroup_from_id(cgrp_id);
if (!acquired)
return 0;
css = &acquired->self;
css_task_cnt = 0;
bpf_for_each(css_task, task, css, CSS_TASK_ITER_PROCS) {
if (task->pid == target_pid)
css_task_cnt++;
}
bpf_cgroup_release(acquired);
return 0;
}