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=Tpa97GrvzuzVNO5nM6b7o... Signed-off-by: Andrea Righi andrea.righi@canonical.com

Acked-by: Jiri Olsa jolsa@kernel.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@canonical.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