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anakryikoAlexei Starovoitov
anakryiko
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Alexei Starovoitov
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selftests/bpf: Add BPF ringbuf selftests
Both singleton BPF ringbuf and BPF ringbuf with map-in-map use cases are tested. Also reserve+submit/discards and output variants of API are validated. Signed-off-by: Andrii Nakryiko <[email protected]> Signed-off-by: Daniel Borkmann <[email protected]> Link: https://lore.kernel.org/bpf/[email protected] Signed-off-by: Alexei Starovoitov <[email protected]>
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‎tools/testing/selftests/bpf/prog_tests/ringbuf.c

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// SPDX-License-Identifier: GPL-2.0
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#define _GNU_SOURCE
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#include <linux/compiler.h>
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#include <asm/barrier.h>
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#include <test_progs.h>
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#include <sys/mman.h>
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#include <sys/epoll.h>
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#include <time.h>
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#include <sched.h>
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#include <signal.h>
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#include <pthread.h>
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#include <sys/sysinfo.h>
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#include <linux/perf_event.h>
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#include <linux/ring_buffer.h>
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#include "test_ringbuf.skel.h"
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#define EDONE 7777
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static int duration = 0;
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struct sample {
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int pid;
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int seq;
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long value;
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char comm[16];
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};
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static int sample_cnt;
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static int process_sample(void *ctx, void *data, size_t len)
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{
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struct sample *s = data;
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sample_cnt++;
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switch (s->seq) {
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case 0:
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CHECK(s->value != 333, "sample1_value", "exp %ld, got %ld\n",
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333L, s->value);
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return 0;
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case 1:
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CHECK(s->value != 777, "sample2_value", "exp %ld, got %ld\n",
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777L, s->value);
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return -EDONE;
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default:
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/* we don't care about the rest */
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return 0;
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}
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}
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static struct test_ringbuf *skel;
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static struct ring_buffer *ringbuf;
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static void trigger_samples()
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{
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skel->bss->dropped = 0;
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skel->bss->total = 0;
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skel->bss->discarded = 0;
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/* trigger exactly two samples */
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skel->bss->value = 333;
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syscall(__NR_getpgid);
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skel->bss->value = 777;
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syscall(__NR_getpgid);
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}
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static void *poll_thread(void *input)
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{
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long timeout = (long)input;
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return (void *)(long)ring_buffer__poll(ringbuf, timeout);
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}
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void test_ringbuf(void)
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{
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const size_t rec_sz = BPF_RINGBUF_HDR_SZ + sizeof(struct sample);
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pthread_t thread;
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long bg_ret = -1;
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int err;
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skel = test_ringbuf__open_and_load();
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if (CHECK(!skel, "skel_open_load", "skeleton open&load failed\n"))
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return;
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/* only trigger BPF program for current process */
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skel->bss->pid = getpid();
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ringbuf = ring_buffer__new(bpf_map__fd(skel->maps.ringbuf),
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process_sample, NULL, NULL);
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if (CHECK(!ringbuf, "ringbuf_create", "failed to create ringbuf\n"))
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goto cleanup;
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err = test_ringbuf__attach(skel);
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if (CHECK(err, "skel_attach", "skeleton attachment failed: %d\n", err))
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goto cleanup;
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trigger_samples();
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/* 2 submitted + 1 discarded records */
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CHECK(skel->bss->avail_data != 3 * rec_sz,
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"err_avail_size", "exp %ld, got %ld\n",
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3L * rec_sz, skel->bss->avail_data);
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CHECK(skel->bss->ring_size != 4096,
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"err_ring_size", "exp %ld, got %ld\n",
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4096L, skel->bss->ring_size);
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CHECK(skel->bss->cons_pos != 0,
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"err_cons_pos", "exp %ld, got %ld\n",
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0L, skel->bss->cons_pos);
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CHECK(skel->bss->prod_pos != 3 * rec_sz,
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"err_prod_pos", "exp %ld, got %ld\n",
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3L * rec_sz, skel->bss->prod_pos);
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/* poll for samples */
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err = ring_buffer__poll(ringbuf, -1);
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/* -EDONE is used as an indicator that we are done */
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if (CHECK(err != -EDONE, "err_done", "done err: %d\n", err))
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goto cleanup;
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/* we expect extra polling to return nothing */
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err = ring_buffer__poll(ringbuf, 0);
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if (CHECK(err != 0, "extra_samples", "poll result: %d\n", err))
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goto cleanup;
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CHECK(skel->bss->dropped != 0, "err_dropped", "exp %ld, got %ld\n",
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0L, skel->bss->dropped);
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CHECK(skel->bss->total != 2, "err_total", "exp %ld, got %ld\n",
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2L, skel->bss->total);
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CHECK(skel->bss->discarded != 1, "err_discarded", "exp %ld, got %ld\n",
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1L, skel->bss->discarded);
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/* now validate consumer position is updated and returned */
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trigger_samples();
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CHECK(skel->bss->cons_pos != 3 * rec_sz,
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"err_cons_pos", "exp %ld, got %ld\n",
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3L * rec_sz, skel->bss->cons_pos);
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err = ring_buffer__poll(ringbuf, -1);
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CHECK(err <= 0, "poll_err", "err %d\n", err);
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/* start poll in background w/ long timeout */
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err = pthread_create(&thread, NULL, poll_thread, (void *)(long)10000);
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if (CHECK(err, "bg_poll", "pthread_create failed: %d\n", err))
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goto cleanup;
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/* turn off notifications now */
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skel->bss->flags = BPF_RB_NO_WAKEUP;
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/* give background thread a bit of a time */
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usleep(50000);
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trigger_samples();
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/* sleeping arbitrarily is bad, but no better way to know that
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* epoll_wait() **DID NOT** unblock in background thread
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*/
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usleep(50000);
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/* background poll should still be blocked */
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err = pthread_tryjoin_np(thread, (void **)&bg_ret);
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if (CHECK(err != EBUSY, "try_join", "err %d\n", err))
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goto cleanup;
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/* BPF side did everything right */
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CHECK(skel->bss->dropped != 0, "err_dropped", "exp %ld, got %ld\n",
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0L, skel->bss->dropped);
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CHECK(skel->bss->total != 2, "err_total", "exp %ld, got %ld\n",
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2L, skel->bss->total);
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CHECK(skel->bss->discarded != 1, "err_discarded", "exp %ld, got %ld\n",
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1L, skel->bss->discarded);
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/* clear flags to return to "adaptive" notification mode */
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skel->bss->flags = 0;
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/* produce new samples, no notification should be triggered, because
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* consumer is now behind
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*/
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trigger_samples();
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/* background poll should still be blocked */
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err = pthread_tryjoin_np(thread, (void **)&bg_ret);
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if (CHECK(err != EBUSY, "try_join", "err %d\n", err))
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goto cleanup;
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/* now force notifications */
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skel->bss->flags = BPF_RB_FORCE_WAKEUP;
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sample_cnt = 0;
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trigger_samples();
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/* now we should get a pending notification */
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usleep(50000);
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err = pthread_tryjoin_np(thread, (void **)&bg_ret);
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if (CHECK(err, "join_bg", "err %d\n", err))
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goto cleanup;
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if (CHECK(bg_ret != 1, "bg_ret", "epoll_wait result: %ld", bg_ret))
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goto cleanup;
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/* 3 rounds, 2 samples each */
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CHECK(sample_cnt != 6, "wrong_sample_cnt",
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"expected to see %d samples, got %d\n", 6, sample_cnt);
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/* BPF side did everything right */
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CHECK(skel->bss->dropped != 0, "err_dropped", "exp %ld, got %ld\n",
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0L, skel->bss->dropped);
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CHECK(skel->bss->total != 2, "err_total", "exp %ld, got %ld\n",
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2L, skel->bss->total);
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CHECK(skel->bss->discarded != 1, "err_discarded", "exp %ld, got %ld\n",
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1L, skel->bss->discarded);
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test_ringbuf__detach(skel);
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cleanup:
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ring_buffer__free(ringbuf);
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test_ringbuf__destroy(skel);
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}

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

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// SPDX-License-Identifier: GPL-2.0
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#define _GNU_SOURCE
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#include <test_progs.h>
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#include <sys/epoll.h>
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#include "test_ringbuf_multi.skel.h"
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static int duration = 0;
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struct sample {
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int pid;
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int seq;
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long value;
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char comm[16];
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};
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static int process_sample(void *ctx, void *data, size_t len)
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{
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int ring = (unsigned long)ctx;
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struct sample *s = data;
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switch (s->seq) {
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case 0:
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CHECK(ring != 1, "sample1_ring", "exp %d, got %d\n", 1, ring);
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CHECK(s->value != 333, "sample1_value", "exp %ld, got %ld\n",
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333L, s->value);
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break;
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case 1:
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CHECK(ring != 2, "sample2_ring", "exp %d, got %d\n", 2, ring);
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CHECK(s->value != 777, "sample2_value", "exp %ld, got %ld\n",
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777L, s->value);
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break;
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default:
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CHECK(true, "extra_sample", "unexpected sample seq %d, val %ld\n",
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s->seq, s->value);
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return -1;
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}
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return 0;
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}
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void test_ringbuf_multi(void)
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{
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struct test_ringbuf_multi *skel;
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struct ring_buffer *ringbuf;
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int err;
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skel = test_ringbuf_multi__open_and_load();
48+
if (CHECK(!skel, "skel_open_load", "skeleton open&load failed\n"))
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return;
50+
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/* only trigger BPF program for current process */
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skel->bss->pid = getpid();
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ringbuf = ring_buffer__new(bpf_map__fd(skel->maps.ringbuf1),
55+
process_sample, (void *)(long)1, NULL);
56+
if (CHECK(!ringbuf, "ringbuf_create", "failed to create ringbuf\n"))
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goto cleanup;
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err = ring_buffer__add(ringbuf, bpf_map__fd(skel->maps.ringbuf2),
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process_sample, (void *)(long)2);
61+
if (CHECK(err, "ringbuf_add", "failed to add another ring\n"))
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goto cleanup;
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err = test_ringbuf_multi__attach(skel);
65+
if (CHECK(err, "skel_attach", "skeleton attachment failed: %d\n", err))
66+
goto cleanup;
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/* trigger few samples, some will be skipped */
69+
skel->bss->target_ring = 0;
70+
skel->bss->value = 333;
71+
syscall(__NR_getpgid);
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/* skipped, no ringbuf in slot 1 */
74+
skel->bss->target_ring = 1;
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skel->bss->value = 555;
76+
syscall(__NR_getpgid);
77+
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skel->bss->target_ring = 2;
79+
skel->bss->value = 777;
80+
syscall(__NR_getpgid);
81+
82+
/* poll for samples, should get 2 ringbufs back */
83+
err = ring_buffer__poll(ringbuf, -1);
84+
if (CHECK(err != 4, "poll_res", "expected 4 records, got %d\n", err))
85+
goto cleanup;
86+
87+
/* expect extra polling to return nothing */
88+
err = ring_buffer__poll(ringbuf, 0);
89+
if (CHECK(err < 0, "extra_samples", "poll result: %d\n", err))
90+
goto cleanup;
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92+
CHECK(skel->bss->dropped != 0, "err_dropped", "exp %ld, got %ld\n",
93+
0L, skel->bss->dropped);
94+
CHECK(skel->bss->skipped != 1, "err_skipped", "exp %ld, got %ld\n",
95+
1L, skel->bss->skipped);
96+
CHECK(skel->bss->total != 2, "err_total", "exp %ld, got %ld\n",
97+
2L, skel->bss->total);
98+
99+
cleanup:
100+
ring_buffer__free(ringbuf);
101+
test_ringbuf_multi__destroy(skel);
102+
}

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

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// SPDX-License-Identifier: GPL-2.0
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// Copyright (c) 2020 Facebook
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#include <linux/bpf.h>
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#include <bpf/bpf_helpers.h>
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char _license[] SEC("license") = "GPL";
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9+
struct sample {
10+
int pid;
11+
int seq;
12+
long value;
13+
char comm[16];
14+
};
15+
16+
struct {
17+
__uint(type, BPF_MAP_TYPE_RINGBUF);
18+
__uint(max_entries, 1 << 12);
19+
} ringbuf SEC(".maps");
20+
21+
/* inputs */
22+
int pid = 0;
23+
long value = 0;
24+
long flags = 0;
25+
26+
/* outputs */
27+
long total = 0;
28+
long discarded = 0;
29+
long dropped = 0;
30+
31+
long avail_data = 0;
32+
long ring_size = 0;
33+
long cons_pos = 0;
34+
long prod_pos = 0;
35+
36+
/* inner state */
37+
long seq = 0;
38+
39+
SEC("tp/syscalls/sys_enter_getpgid")
40+
int test_ringbuf(void *ctx)
41+
{
42+
int cur_pid = bpf_get_current_pid_tgid() >> 32;
43+
struct sample *sample;
44+
int zero = 0;
45+
46+
if (cur_pid != pid)
47+
return 0;
48+
49+
sample = bpf_ringbuf_reserve(&ringbuf, sizeof(*sample), 0);
50+
if (!sample) {
51+
__sync_fetch_and_add(&dropped, 1);
52+
return 1;
53+
}
54+
55+
sample->pid = pid;
56+
bpf_get_current_comm(sample->comm, sizeof(sample->comm));
57+
sample->value = value;
58+
59+
sample->seq = seq++;
60+
__sync_fetch_and_add(&total, 1);
61+
62+
if (sample->seq & 1) {
63+
/* copy from reserved sample to a new one... */
64+
bpf_ringbuf_output(&ringbuf, sample, sizeof(*sample), flags);
65+
/* ...and then discard reserved sample */
66+
bpf_ringbuf_discard(sample, flags);
67+
__sync_fetch_and_add(&discarded, 1);
68+
} else {
69+
bpf_ringbuf_submit(sample, flags);
70+
}
71+
72+
avail_data = bpf_ringbuf_query(&ringbuf, BPF_RB_AVAIL_DATA);
73+
ring_size = bpf_ringbuf_query(&ringbuf, BPF_RB_RING_SIZE);
74+
cons_pos = bpf_ringbuf_query(&ringbuf, BPF_RB_CONS_POS);
75+
prod_pos = bpf_ringbuf_query(&ringbuf, BPF_RB_PROD_POS);
76+
77+
return 0;
78+
}

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