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Date: Fri, 5 May 2023 11:20:54 +0800
From: Feng Zhou <zhoufeng.zf@...edance.com>
To: Yonghong Song <yhs@...a.com>, martin.lau@...ux.dev, ast@...nel.org,
daniel@...earbox.net, andrii@...nel.org, song@...nel.org, yhs@...com,
john.fastabend@...il.com, kpsingh@...nel.org, sdf@...gle.com,
haoluo@...gle.com, jolsa@...nel.org, davem@...emloft.net,
edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com, mykolal@...com,
shuah@...nel.org
Cc: bpf@...r.kernel.org, linux-kernel@...r.kernel.org,
netdev@...r.kernel.org, linux-kselftest@...r.kernel.org,
yangzhenze@...edance.com, wangdongdong.6@...edance.com
Subject: Re: Re: [PATCH bpf-next v5 2/2] selftests/bpf: Add testcase for
bpf_task_under_cgroup
在 2023/5/4 22:46, Yonghong Song 写道:
>
>
> On 5/3/23 8:15 PM, Feng zhou wrote:
>> From: Feng Zhou <zhoufeng.zf@...edance.com>
>>
>> test_progs:
>> Tests new kfunc bpf_task_under_cgroup().
>>
>> The bpf program saves the new task's pid within a given cgroup to
>> the remote_pid, which is convenient for the user-mode program to
>> verify the test correctness.
>>
>> The user-mode program creates its own mount namespace, and mounts the
>> cgroupsv2 hierarchy in there, call the fork syscall, then check if
>> remote_pid and local_pid are unequal.
>>
>> Signed-off-by: Feng Zhou <zhoufeng.zf@...edance.com>
>
> Ack with a few nits below. You can carry my Ack in the
> next revision.
>
> Acked-by: Yonghong Song <yhs@...com>
>
>
Will do
>> ---
>> tools/testing/selftests/bpf/DENYLIST.s390x | 1 +
>> .../bpf/prog_tests/task_under_cgroup.c | 54 +++++++++++++++++++
>> .../bpf/progs/test_task_under_cgroup.c | 51 ++++++++++++++++++
>> 3 files changed, 106 insertions(+)
>> create mode 100644
>> tools/testing/selftests/bpf/prog_tests/task_under_cgroup.c
>> create mode 100644
>> tools/testing/selftests/bpf/progs/test_task_under_cgroup.c
>>
>> diff --git a/tools/testing/selftests/bpf/DENYLIST.s390x
>> b/tools/testing/selftests/bpf/DENYLIST.s390x
>> index c7463f3ec3c0..5061d9e24c16 100644
>> --- a/tools/testing/selftests/bpf/DENYLIST.s390x
>> +++ b/tools/testing/selftests/bpf/DENYLIST.s390x
>> @@ -26,3 +26,4 @@ user_ringbuf # failed to
>> find kernel BTF type ID of
>> verif_stats #
>> trace_vprintk__open_and_load unexpected error:
>> -9 (?)
>> xdp_bonding # failed to auto-attach
>> program 'trace_on_entry': -524 (trampoline)
>> xdp_metadata # JIT does not support
>> calling kernel function (kfunc)
>> +test_task_under_cgroup # JIT does not support
>> calling kernel function (kfunc)
>> diff --git
>> a/tools/testing/selftests/bpf/prog_tests/task_under_cgroup.c
>> b/tools/testing/selftests/bpf/prog_tests/task_under_cgroup.c
>> new file mode 100644
>> index 000000000000..fa3a98eae5ef
>> --- /dev/null
>> +++ b/tools/testing/selftests/bpf/prog_tests/task_under_cgroup.c
>> @@ -0,0 +1,54 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/* Copyright (c) 2023 Bytedance */
>> +
>> +#include <sys/syscall.h>
>> +#include <test_progs.h>
>> +#include <cgroup_helpers.h>
>> +#include "test_task_under_cgroup.skel.h"
>> +
>> +#define FOO "/foo"
>> +
>> +void test_task_under_cgroup(void)
>> +{
>> + struct test_task_under_cgroup *skel;
>> + int ret, foo = -1;
>
> You do not need to initialize 'foo' here.
>
>> + pid_t pid;
>> +
>> + foo = test__join_cgroup(FOO);
>> + if (!ASSERT_OK(foo < 0, "cgroup_join_foo"))
>> + return;
>> +
>> + skel = test_task_under_cgroup__open();
>> + if (!ASSERT_OK_PTR(skel, "test_task_under_cgroup__open"))
>> + goto cleanup;
>> +
>> + skel->rodata->local_pid = getpid();
>> + skel->bss->remote_pid = getpid();
>> + skel->rodata->cgid = get_cgroup_id(FOO);
>> +
>> + ret = test_task_under_cgroup__load(skel);
>> + if (!ASSERT_OK(ret, "test_task_under_cgroup__load"))
>> + goto cleanup;
>> +
>> + ret = test_task_under_cgroup__attach(skel);
>> + if (!ASSERT_OK(ret, "test_task_under_cgroup__attach"))
>> + goto cleanup;
>> +
>> + pid = fork();
>> + if (pid == 0)
>> + exit(0);
>> +
>> + ret = (pid == -1);
>> + if (ASSERT_OK(ret, "fork process"))
>> + wait(NULL);
>> +
>> + test_task_under_cgroup__detach(skel);
>> +
>> + ASSERT_NEQ(skel->bss->remote_pid, skel->rodata->local_pid,
>> + "test task_under_cgroup");
>> +
>> +cleanup:
>> + close(foo);
>> +
>> + test_task_under_cgroup__destroy(skel);
>
> Let us just do:
> cleanup:
> test_task_under_cgroup__destroy(skel);
> close(foo);
>
> This is the reverse order of test__join_cgroup() and
> test_task_under_cgroup__open().
>
>> +}
>> diff --git
>> a/tools/testing/selftests/bpf/progs/test_task_under_cgroup.c
>> b/tools/testing/selftests/bpf/progs/test_task_under_cgroup.c
>> new file mode 100644
>> index 000000000000..79d98e65c7eb
>> --- /dev/null
>> +++ b/tools/testing/selftests/bpf/progs/test_task_under_cgroup.c
>> @@ -0,0 +1,51 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/* Copyright (c) 2023 Bytedance */
>> +
>> +#include <vmlinux.h>
>> +#include <bpf/bpf_tracing.h>
>> +#include <bpf/bpf_helpers.h>
>> +
>> +#include "bpf_misc.h"
>> +
>> +struct cgroup *bpf_cgroup_from_id(u64 cgid) __ksym;
>> +long bpf_task_under_cgroup(struct task_struct *task, struct cgroup
>> *ancestor) __ksym;
>> +void bpf_cgroup_release(struct cgroup *p) __ksym;
>> +struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym;
>> +void bpf_task_release(struct task_struct *p) __ksym;
>> +
>> +const volatile int local_pid;
>> +const volatile __u64 cgid;
>> +int remote_pid;
>> +
>> +SEC("tp_btf/task_newtask")
>> +int BPF_PROG(handle__task_newtask, struct task_struct *task, u64
>> clone_flags)
>> +{
>> + struct cgroup *cgrp = NULL;
>> + struct task_struct *acquired;
>> +
>> + if (local_pid != (bpf_get_current_pid_tgid() >> 32))
>> + return 0;
>> +
>> + acquired = bpf_task_acquire(task);
>> + if (!acquired)
>> + return 0;
>> +
>> + if (local_pid == acquired->tgid)
>> + goto out;
>> +
>> + cgrp = bpf_cgroup_from_id(cgid);
>> + if (!cgrp)
>> + goto out;
>> +
>> + if (bpf_task_under_cgroup(acquired, cgrp))
>> + remote_pid = acquired->tgid;
>> +
>> +out:
>> + if (acquired)
>> + bpf_task_release(acquired);
>> + if (cgrp)
>> + bpf_cgroup_release(cgrp);
>
> Let us do:
> out:
> if (cgrp)
> bpf_cgroup_release(cgrp);
> bpf_task_release(acquired);
>
>> + return 0;
>> +}
>> +
>> +char _license[] SEC("license") = "GPL";
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