Commit 638a485c authored by Andrea Righi's avatar Andrea Righi Committed by Andrii Nakryiko
Browse files

selftests/bpf: Add ring_buffer__consume_n test. 



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.

Signed-off-by: default avatarAndrea Righi <andrea.righi@canonical.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/lkml/CAEf4BzaR4zqUpDmj44KNLdpJ=Tpa97GrvzuzVNO5nM6b7oWd1w@mail.gmail.com
Link: https://lore.kernel.org/bpf/20240425140627.112728-1-andrea.righi@canonical.com
parent 8ec3bf5c

tools/testing/selftests/bpf/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -456,7 +456,7 @@ 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 \

tools/testing/selftests/bpf/prog_tests/ringbuf.c

+65 −0
Original line number Diff line number Diff line
@@ -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 +327,68 @@ 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);

		if (!ASSERT_EQ(err, N_SAMPLES, "rb_consume"))

			goto cleanup_ringbuf;

	}



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 +447,8 @@ 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();

}

tools/testing/selftests/bpf/progs/test_ringbuf_n.c

0 → 100644
+47 −0
Original line number Diff line number Diff line 
// 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;

}