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Message-ID: <ZiqPqEIBNEwPO2Am@krava>
Date: Thu, 25 Apr 2024 19:15:20 +0200
From: Jiri Olsa <olsajiri@...il.com>
To: Andrea Righi <andrea.righi@...onical.com>
Cc: Andrii Nakryiko <andrii@...nel.org>,
Eduard Zingerman <eddyz87@...il.com>,
Mykola Lysenko <mykolal@...com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Martin KaFai Lau <martin.lau@...ux.dev>, Song Liu <song@...nel.org>,
Yonghong Song <yonghong.song@...ux.dev>,
John Fastabend <john.fastabend@...il.com>,
KP Singh <kpsingh@...nel.org>, Stanislav Fomichev <sdf@...gle.com>,
Hao Luo <haoluo@...gle.com>, Shuah Khan <shuah@...nel.org>,
linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v3] selftests/bpf: Add ring_buffer__consume_n test.
On Thu, Apr 25, 2024 at 04:06:27PM +0200, Andrea Righi wrote:
> Add a testcase for the ring_buffer__consume_n() API.
>
> The test produces multiple samples in a ring buffer, using a
> sys_getpid() fentry prog, and consumes them from user-space in batches,
> rather than consuming all of them greedily, like ring_buffer__consume()
> does.
>
> Link: https://lore.kernel.org/lkml/CAEf4BzaR4zqUpDmj44KNLdpJ=Tpa97GrvzuzVNO5nM6b7oWd1w@mail.gmail.com
> Signed-off-by: Andrea Righi <andrea.righi@...onical.com>
Acked-by: Jiri Olsa <jolsa@...nel.org>
jirka
> ---
> tools/testing/selftests/bpf/Makefile | 2 +-
> .../selftests/bpf/prog_tests/ringbuf.c | 64 +++++++++++++++++++
> .../selftests/bpf/progs/test_ringbuf_n.c | 47 ++++++++++++++
> 3 files changed, 112 insertions(+), 1 deletion(-)
> create mode 100644 tools/testing/selftests/bpf/progs/test_ringbuf_n.c
>
> ChangeLog v2 -> v3:
> - move skel_n inside ringbuf_n_subtest()
>
> ChangeLog v1 -> v2:
> - replace CHECK() with ASSERT_EQ()
> - fix skel -> skel_n
> - drop unused "seq" field from struct sample
>
> diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
> index edc73f8f5aef..6332277edeca 100644
> --- a/tools/testing/selftests/bpf/Makefile
> +++ b/tools/testing/selftests/bpf/Makefile
> @@ -455,7 +455,7 @@ LINKED_SKELS := test_static_linked.skel.h linked_funcs.skel.h \
> LSKELS := fentry_test.c fexit_test.c fexit_sleep.c atomics.c \
> trace_printk.c trace_vprintk.c map_ptr_kern.c \
> core_kern.c core_kern_overflow.c test_ringbuf.c \
> - test_ringbuf_map_key.c
> + test_ringbuf_n.c test_ringbuf_map_key.c
>
> # Generate both light skeleton and libbpf skeleton for these
> LSKELS_EXTRA := test_ksyms_module.c test_ksyms_weak.c kfunc_call_test.c \
> diff --git a/tools/testing/selftests/bpf/prog_tests/ringbuf.c b/tools/testing/selftests/bpf/prog_tests/ringbuf.c
> index 48c5695b7abf..2f064d6952f0 100644
> --- a/tools/testing/selftests/bpf/prog_tests/ringbuf.c
> +++ b/tools/testing/selftests/bpf/prog_tests/ringbuf.c
> @@ -13,6 +13,7 @@
> #include <linux/perf_event.h>
> #include <linux/ring_buffer.h>
> #include "test_ringbuf.lskel.h"
> +#include "test_ringbuf_n.lskel.h"
> #include "test_ringbuf_map_key.lskel.h"
>
> #define EDONE 7777
> @@ -326,6 +327,67 @@ static void ringbuf_subtest(void)
> test_ringbuf_lskel__destroy(skel);
> }
>
> +/*
> + * Test ring_buffer__consume_n() by producing N_TOT_SAMPLES samples in the ring
> + * buffer, via getpid(), and consuming them in chunks of N_SAMPLES.
> + */
> +#define N_TOT_SAMPLES 32
> +#define N_SAMPLES 4
> +
> +/* Sample value to verify the callback validity */
> +#define SAMPLE_VALUE 42L
> +
> +static int process_n_sample(void *ctx, void *data, size_t len)
> +{
> + struct sample *s = data;
> +
> + ASSERT_EQ(s->value, SAMPLE_VALUE, "sample_value");
> +
> + return 0;
> +}
> +
> +static void ringbuf_n_subtest(void)
> +{
> + struct test_ringbuf_n_lskel *skel_n;
> + int err, i;
> +
> + skel_n = test_ringbuf_n_lskel__open();
> + if (!ASSERT_OK_PTR(skel_n, "test_ringbuf_n_lskel__open"))
> + return;
> +
> + skel_n->maps.ringbuf.max_entries = getpagesize();
> + skel_n->bss->pid = getpid();
> +
> + err = test_ringbuf_n_lskel__load(skel_n);
> + if (!ASSERT_OK(err, "test_ringbuf_n_lskel__load"))
> + goto cleanup;
> +
> + ringbuf = ring_buffer__new(skel_n->maps.ringbuf.map_fd,
> + process_n_sample, NULL, NULL);
> + if (!ASSERT_OK_PTR(ringbuf, "ring_buffer__new"))
> + goto cleanup;
> +
> + err = test_ringbuf_n_lskel__attach(skel_n);
> + if (!ASSERT_OK(err, "test_ringbuf_n_lskel__attach"))
> + goto cleanup_ringbuf;
> +
> + /* Produce N_TOT_SAMPLES samples in the ring buffer by calling getpid() */
> + skel_n->bss->value = SAMPLE_VALUE;
> + for (i = 0; i < N_TOT_SAMPLES; i++)
> + syscall(__NR_getpgid);
> +
> + /* Consume all samples from the ring buffer in batches of N_SAMPLES */
> + for (i = 0; i < N_TOT_SAMPLES; i += err) {
> + err = ring_buffer__consume_n(ringbuf, N_SAMPLES);
> + ASSERT_EQ(err, N_SAMPLES, "rb_consume");
> + }
> +
> +cleanup_ringbuf:
> + ring_buffer__free(ringbuf);
> +cleanup:
> + test_ringbuf_n_lskel__destroy(skel_n);
> +}
> +
> static int process_map_key_sample(void *ctx, void *data, size_t len)
> {
> struct sample *s;
> @@ -384,6 +446,8 @@ void test_ringbuf(void)
> {
> if (test__start_subtest("ringbuf"))
> ringbuf_subtest();
> + if (test__start_subtest("ringbuf_n"))
> + ringbuf_n_subtest();
> if (test__start_subtest("ringbuf_map_key"))
> ringbuf_map_key_subtest();
> }
> diff --git a/tools/testing/selftests/bpf/progs/test_ringbuf_n.c b/tools/testing/selftests/bpf/progs/test_ringbuf_n.c
> new file mode 100644
> index 000000000000..8669eb42dbe0
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/progs/test_ringbuf_n.c
> @@ -0,0 +1,47 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (c) 2024 Andrea Righi <andrea.righi@...onical.com>
> +
> +#include <linux/bpf.h>
> +#include <sched.h>
> +#include <unistd.h>
> +#include <bpf/bpf_helpers.h>
> +#include "bpf_misc.h"
> +
> +char _license[] SEC("license") = "GPL";
> +
> +#define TASK_COMM_LEN 16
> +
> +struct sample {
> + int pid;
> + long value;
> + char comm[16];
> +};
> +
> +struct {
> + __uint(type, BPF_MAP_TYPE_RINGBUF);
> +} ringbuf SEC(".maps");
> +
> +int pid = 0;
> +long value = 0;
> +
> +SEC("fentry/" SYS_PREFIX "sys_getpgid")
> +int test_ringbuf_n(void *ctx)
> +{
> + int cur_pid = bpf_get_current_pid_tgid() >> 32;
> + struct sample *sample;
> +
> + if (cur_pid != pid)
> + return 0;
> +
> + sample = bpf_ringbuf_reserve(&ringbuf, sizeof(*sample), 0);
> + if (!sample)
> + return 0;
> +
> + sample->pid = pid;
> + sample->value = value;
> + bpf_get_current_comm(sample->comm, sizeof(sample->comm));
> +
> + bpf_ringbuf_submit(sample, 0);
> +
> + return 0;
> +}
> --
> 2.43.0
>
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