From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2FCB3362 for ; Tue, 31 Oct 2023 00:14:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="DHnhkc35" Received: from out-185.mta0.migadu.com (out-185.mta0.migadu.com [IPv6:2001:41d0:1004:224b::b9]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 40A39B3 for ; Mon, 30 Oct 2023 17:14:33 -0700 (PDT) Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1698711271; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=kop3YU72ZWeLXrFFlj38Wcp2BT7i2sfdnRxISQs9euA=; b=DHnhkc359jotLY0OBHTtxvs5lJWlDusq3FVn1Yf4bHRlNRhYVI11wfJVG+o0PpnEMK8EZM TUSusr3uP33Z0AhMPEB31XHa1vMU3Z0VR/F/U+NJzUJQ+HiZTFZGJaP0/4Vq/SOqmAoUYB QEwIE6394JuzkOkqrv3sjVrqax7ky2I= Date: Mon, 30 Oct 2023 17:14:24 -0700 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf-next v3 2/3] selftests/bpf: Add tests for css_task iter combining with cgroup iter Content-Language: en-GB To: Chuyi Zhou , bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@kernel.org References: <20231025075914.30979-1-zhouchuyi@bytedance.com> <20231025075914.30979-3-zhouchuyi@bytedance.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yonghong Song In-Reply-To: <20231025075914.30979-3-zhouchuyi@bytedance.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 10/25/23 12:59 AM, Chuyi Zhou wrote: > 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 Ack with a few nits below: Acked-by: Yonghong Song > --- > .../selftests/bpf/prog_tests/cgroup_iter.c | 33 +++++++++++++++ > .../selftests/bpf/progs/iters_css_task.c | 41 +++++++++++++++++++ > 2 files changed, 74 insertions(+) > > diff --git a/tools/testing/selftests/bpf/prog_tests/cgroup_iter.c b/tools/testing/selftests/bpf/prog_tests/cgroup_iter.c > index e02feb5fae97..3679687a6927 100644 > --- a/tools/testing/selftests/bpf/prog_tests/cgroup_iter.c > +++ b/tools/testing/selftests/bpf/prog_tests/cgroup_iter.c > @@ -4,6 +4,7 @@ > #include > #include > #include > +#include "iters_css_task.skel.h" > #include "cgroup_iter.skel.h" > #include "cgroup_helpers.h" > > @@ -263,6 +264,35 @@ static void test_walk_dead_self_only(struct cgroup_iter *skel) > close(cgrp_fd); > } > > +static void test_walk_self_only_css_task(void) > +{ > + struct iters_css_task *skel = NULL; '= NULL' is unnecessary. > + 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(); > diff --git a/tools/testing/selftests/bpf/progs/iters_css_task.c b/tools/testing/selftests/bpf/progs/iters_css_task.c > index 5089ce384a1c..0974e6f44328 100644 > --- a/tools/testing/selftests/bpf/progs/iters_css_task.c > +++ b/tools/testing/selftests/bpf/progs/iters_css_task.c > @@ -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 +46,43 @@ 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; > + > + 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"); > + > + BPF_SEQ_PRINTF(seq, "%8llu\n", cgroup_id(cgrp)); > + > + acquired = bpf_cgroup_from_id(cgroup_id(cgrp)); cgroup_id(cgrp) needs only one call. > + 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; > +}