Messages in this thread Patch in this message | | | Date | Fri, 28 Apr 2023 09:32:01 -0700 | Subject | Re: [PATCH bpf-next v4 2/2] selftests/bpf: Add testcase for bpf_task_under_cgroup | From | Yonghong Song <> |
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On 4/28/23 12:17 AM, Feng zhou wrote: > From: Feng Zhou <zhoufeng.zf@bytedance.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@bytedance.com>
Ack with a few nits below.
Acked-by: Yonghong Song <yhs@fb.com>
> --- > tools/testing/selftests/bpf/DENYLIST.s390x | 1 + > .../bpf/prog_tests/task_under_cgroup.c | 55 +++++++++++++++++++ > .../bpf/progs/test_task_under_cgroup.c | 51 +++++++++++++++++ > 3 files changed, 107 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..5e79dff86dec > --- /dev/null > +++ b/tools/testing/selftests/bpf/prog_tests/task_under_cgroup.c > @@ -0,0 +1,55 @@ > +// 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; > + 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); > + else if (pid == -1) > + printf("Couldn't fork process!\n");
ASSERT_* is preferred compared to 'printf'. Maybe ASSERT_TRUE(0, "Couldn't 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: > + if (foo >= 0)
"if (foo >= 0)" is not needed. 'foo' is guaranteed ">= 0" as this point.
> + close(foo); > + > + test_task_under_cgroup__destroy(skel); > +} > 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..5bcb726d6d0a > --- /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 long cgid; cgid cannot be a negative number. So let us do 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 = NULL;
"acquired = NULL" is not needed. Just do "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); > + return 0; > +} > + > +char _license[] SEC("license") = "GPL";
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