1// SPDX-License-Identifier: GPL-2.0
  2#define _GNU_SOURCE
  3#include <linux/compiler.h>
  4#include <asm/barrier.h>
  5#include <test_progs.h>
  6#include <sys/mman.h>
  7#include <sys/epoll.h>
  8#include <time.h>
  9#include <sched.h>
 10#include <signal.h>
 11#include <pthread.h>
 12#include <sys/sysinfo.h>
 13#include <linux/perf_event.h>
 14#include <linux/ring_buffer.h>
 15#include "test_ringbuf.skel.h"
 16
 17#define EDONE 7777
 18
 19static int duration = 0;
 20
 21struct sample {
 22	int pid;
 23	int seq;
 24	long value;
 25	char comm[16];
 26};
 27
 28static int sample_cnt;
 29
 30static void atomic_inc(int *cnt)
 31{
 32	__atomic_add_fetch(cnt, 1, __ATOMIC_SEQ_CST);
 33}
 34
 35static int atomic_xchg(int *cnt, int val)
 36{
 37	return __atomic_exchange_n(cnt, val, __ATOMIC_SEQ_CST);
 38}
 39
 40static int process_sample(void *ctx, void *data, size_t len)
 41{
 42	struct sample *s = data;
 43
 44	atomic_inc(&sample_cnt);
 45
 46	switch (s->seq) {
 47	case 0:
 48		CHECK(s->value != 333, "sample1_value", "exp %ld, got %ld\n",
 49		      333L, s->value);
 50		return 0;
 51	case 1:
 52		CHECK(s->value != 777, "sample2_value", "exp %ld, got %ld\n",
 53		      777L, s->value);
 54		return -EDONE;
 55	default:
 56		/* we don't care about the rest */
 57		return 0;
 58	}
 59}
 60
 61static struct test_ringbuf *skel;
 62static struct ring_buffer *ringbuf;
 63
 64static void trigger_samples()
 65{
 66	skel->bss->dropped = 0;
 67	skel->bss->total = 0;
 68	skel->bss->discarded = 0;
 69
 70	/* trigger exactly two samples */
 71	skel->bss->value = 333;
 72	syscall(__NR_getpgid);
 73	skel->bss->value = 777;
 74	syscall(__NR_getpgid);
 75}
 76
 77static void *poll_thread(void *input)
 78{
 79	long timeout = (long)input;
 80
 81	return (void *)(long)ring_buffer__poll(ringbuf, timeout);
 82}
 83
 84void test_ringbuf(void)
 85{
 86	const size_t rec_sz = BPF_RINGBUF_HDR_SZ + sizeof(struct sample);
 87	pthread_t thread;
 88	long bg_ret = -1;
 89	int err, cnt;
 90
 91	skel = test_ringbuf__open_and_load();
 92	if (CHECK(!skel, "skel_open_load", "skeleton open&load failed\n"))
 93		return;
 94
 95	/* only trigger BPF program for current process */
 96	skel->bss->pid = getpid();
 97
 98	ringbuf = ring_buffer__new(bpf_map__fd(skel->maps.ringbuf),
 99				   process_sample, NULL, NULL);
100	if (CHECK(!ringbuf, "ringbuf_create", "failed to create ringbuf\n"))
101		goto cleanup;
102
103	err = test_ringbuf__attach(skel);
104	if (CHECK(err, "skel_attach", "skeleton attachment failed: %d\n", err))
105		goto cleanup;
106
107	trigger_samples();
108
109	/* 2 submitted + 1 discarded records */
110	CHECK(skel->bss->avail_data != 3 * rec_sz,
111	      "err_avail_size", "exp %ld, got %ld\n",
112	      3L * rec_sz, skel->bss->avail_data);
113	CHECK(skel->bss->ring_size != 4096,
114	      "err_ring_size", "exp %ld, got %ld\n",
115	      4096L, skel->bss->ring_size);
116	CHECK(skel->bss->cons_pos != 0,
117	      "err_cons_pos", "exp %ld, got %ld\n",
118	      0L, skel->bss->cons_pos);
119	CHECK(skel->bss->prod_pos != 3 * rec_sz,
120	      "err_prod_pos", "exp %ld, got %ld\n",
121	      3L * rec_sz, skel->bss->prod_pos);
122
123	/* poll for samples */
124	err = ring_buffer__poll(ringbuf, -1);
125
126	/* -EDONE is used as an indicator that we are done */
127	if (CHECK(err != -EDONE, "err_done", "done err: %d\n", err))
128		goto cleanup;
129	cnt = atomic_xchg(&sample_cnt, 0);
130	CHECK(cnt != 2, "cnt", "exp %d samples, got %d\n", 2, cnt);
131
132	/* we expect extra polling to return nothing */
133	err = ring_buffer__poll(ringbuf, 0);
134	if (CHECK(err != 0, "extra_samples", "poll result: %d\n", err))
135		goto cleanup;
136	cnt = atomic_xchg(&sample_cnt, 0);
137	CHECK(cnt != 0, "cnt", "exp %d samples, got %d\n", 0, cnt);
138
139	CHECK(skel->bss->dropped != 0, "err_dropped", "exp %ld, got %ld\n",
140	      0L, skel->bss->dropped);
141	CHECK(skel->bss->total != 2, "err_total", "exp %ld, got %ld\n",
142	      2L, skel->bss->total);
143	CHECK(skel->bss->discarded != 1, "err_discarded", "exp %ld, got %ld\n",
144	      1L, skel->bss->discarded);
145
146	/* now validate consumer position is updated and returned */
147	trigger_samples();
148	CHECK(skel->bss->cons_pos != 3 * rec_sz,
149	      "err_cons_pos", "exp %ld, got %ld\n",
150	      3L * rec_sz, skel->bss->cons_pos);
151	err = ring_buffer__poll(ringbuf, -1);
152	CHECK(err <= 0, "poll_err", "err %d\n", err);
153	cnt = atomic_xchg(&sample_cnt, 0);
154	CHECK(cnt != 2, "cnt", "exp %d samples, got %d\n", 2, cnt);
155
156	/* start poll in background w/ long timeout */
157	err = pthread_create(&thread, NULL, poll_thread, (void *)(long)10000);
158	if (CHECK(err, "bg_poll", "pthread_create failed: %d\n", err))
159		goto cleanup;
160
161	/* turn off notifications now */
162	skel->bss->flags = BPF_RB_NO_WAKEUP;
163
164	/* give background thread a bit of a time */
165	usleep(50000);
166	trigger_samples();
167	/* sleeping arbitrarily is bad, but no better way to know that
168	 * epoll_wait() **DID NOT** unblock in background thread
169	 */
170	usleep(50000);
171	/* background poll should still be blocked */
172	err = pthread_tryjoin_np(thread, (void **)&bg_ret);
173	if (CHECK(err != EBUSY, "try_join", "err %d\n", err))
174		goto cleanup;
175
176	/* BPF side did everything right */
177	CHECK(skel->bss->dropped != 0, "err_dropped", "exp %ld, got %ld\n",
178	      0L, skel->bss->dropped);
179	CHECK(skel->bss->total != 2, "err_total", "exp %ld, got %ld\n",
180	      2L, skel->bss->total);
181	CHECK(skel->bss->discarded != 1, "err_discarded", "exp %ld, got %ld\n",
182	      1L, skel->bss->discarded);
183	cnt = atomic_xchg(&sample_cnt, 0);
184	CHECK(cnt != 0, "cnt", "exp %d samples, got %d\n", 0, cnt);
185
186	/* clear flags to return to "adaptive" notification mode */
187	skel->bss->flags = 0;
188
189	/* produce new samples, no notification should be triggered, because
190	 * consumer is now behind
191	 */
192	trigger_samples();
193
194	/* background poll should still be blocked */
195	err = pthread_tryjoin_np(thread, (void **)&bg_ret);
196	if (CHECK(err != EBUSY, "try_join", "err %d\n", err))
197		goto cleanup;
198
199	/* still no samples, because consumer is behind */
200	cnt = atomic_xchg(&sample_cnt, 0);
201	CHECK(cnt != 0, "cnt", "exp %d samples, got %d\n", 0, cnt);
202
203	skel->bss->dropped = 0;
204	skel->bss->total = 0;
205	skel->bss->discarded = 0;
206
207	skel->bss->value = 333;
208	syscall(__NR_getpgid);
209	/* now force notifications */
210	skel->bss->flags = BPF_RB_FORCE_WAKEUP;
211	skel->bss->value = 777;
212	syscall(__NR_getpgid);
213
214	/* now we should get a pending notification */
215	usleep(50000);
216	err = pthread_tryjoin_np(thread, (void **)&bg_ret);
217	if (CHECK(err, "join_bg", "err %d\n", err))
218		goto cleanup;
219
220	if (CHECK(bg_ret != 1, "bg_ret", "epoll_wait result: %ld", bg_ret))
221		goto cleanup;
222
223	/* 3 rounds, 2 samples each */
224	cnt = atomic_xchg(&sample_cnt, 0);
225	CHECK(cnt != 6, "cnt", "exp %d samples, got %d\n", 6, cnt);
226
227	/* BPF side did everything right */
228	CHECK(skel->bss->dropped != 0, "err_dropped", "exp %ld, got %ld\n",
229	      0L, skel->bss->dropped);
230	CHECK(skel->bss->total != 2, "err_total", "exp %ld, got %ld\n",
231	      2L, skel->bss->total);
232	CHECK(skel->bss->discarded != 1, "err_discarded", "exp %ld, got %ld\n",
233	      1L, skel->bss->discarded);
234
235	test_ringbuf__detach(skel);
236cleanup:
237	ring_buffer__free(ringbuf);
238	test_ringbuf__destroy(skel);
239}