Fix: Consumer return value check after mmap/splice
[lttng-tools.git] / src / common / kernel-consumer / kernel-consumer.c
1 /*
2 * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
3 * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License, version 2 only,
7 * as published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License along
15 * with this program; if not, write to the Free Software Foundation, Inc.,
16 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
17 */
18
19 #define _GNU_SOURCE
20 #include <assert.h>
21 #include <poll.h>
22 #include <pthread.h>
23 #include <stdlib.h>
24 #include <string.h>
25 #include <sys/mman.h>
26 #include <sys/socket.h>
27 #include <sys/types.h>
28 #include <inttypes.h>
29 #include <unistd.h>
30 #include <sys/stat.h>
31
32 #include <common/common.h>
33 #include <common/kernel-ctl/kernel-ctl.h>
34 #include <common/sessiond-comm/sessiond-comm.h>
35 #include <common/sessiond-comm/relayd.h>
36 #include <common/compat/fcntl.h>
37 #include <common/relayd/relayd.h>
38
39 #include "kernel-consumer.h"
40
41 extern struct lttng_consumer_global_data consumer_data;
42 extern int consumer_poll_timeout;
43 extern volatile int consumer_quit;
44
45 /*
46 * Take a snapshot for a specific fd
47 *
48 * Returns 0 on success, < 0 on error
49 */
50 int lttng_kconsumer_take_snapshot(struct lttng_consumer_local_data *ctx,
51 struct lttng_consumer_stream *stream)
52 {
53 int ret = 0;
54 int infd = stream->wait_fd;
55
56 ret = kernctl_snapshot(infd);
57 if (ret != 0) {
58 errno = -ret;
59 perror("Getting sub-buffer snapshot.");
60 }
61
62 return ret;
63 }
64
65 /*
66 * Get the produced position
67 *
68 * Returns 0 on success, < 0 on error
69 */
70 int lttng_kconsumer_get_produced_snapshot(
71 struct lttng_consumer_local_data *ctx,
72 struct lttng_consumer_stream *stream,
73 unsigned long *pos)
74 {
75 int ret;
76 int infd = stream->wait_fd;
77
78 ret = kernctl_snapshot_get_produced(infd, pos);
79 if (ret != 0) {
80 errno = -ret;
81 perror("kernctl_snapshot_get_produced");
82 }
83
84 return ret;
85 }
86
87 int lttng_kconsumer_recv_cmd(struct lttng_consumer_local_data *ctx,
88 int sock, struct pollfd *consumer_sockpoll)
89 {
90 ssize_t ret;
91 struct lttcomm_consumer_msg msg;
92
93 ret = lttcomm_recv_unix_sock(sock, &msg, sizeof(msg));
94 if (ret != sizeof(msg)) {
95 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_CMD);
96 return ret;
97 }
98 if (msg.cmd_type == LTTNG_CONSUMER_STOP) {
99 return -ENOENT;
100 }
101
102 /* relayd needs RCU read-side protection */
103 rcu_read_lock();
104
105 switch (msg.cmd_type) {
106 case LTTNG_CONSUMER_ADD_RELAYD_SOCKET:
107 {
108 ret = consumer_add_relayd_socket(msg.u.relayd_sock.net_index,
109 msg.u.relayd_sock.type, ctx, sock, consumer_sockpoll,
110 &msg.u.relayd_sock.sock);
111 goto end_nosignal;
112 }
113 case LTTNG_CONSUMER_ADD_CHANNEL:
114 {
115 struct lttng_consumer_channel *new_channel;
116
117 DBG("consumer_add_channel %d", msg.u.channel.channel_key);
118 new_channel = consumer_allocate_channel(msg.u.channel.channel_key,
119 -1, -1,
120 msg.u.channel.mmap_len,
121 msg.u.channel.max_sb_size);
122 if (new_channel == NULL) {
123 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
124 goto end_nosignal;
125 }
126 if (ctx->on_recv_channel != NULL) {
127 ret = ctx->on_recv_channel(new_channel);
128 if (ret == 0) {
129 consumer_add_channel(new_channel);
130 } else if (ret < 0) {
131 goto end_nosignal;
132 }
133 } else {
134 consumer_add_channel(new_channel);
135 }
136 goto end_nosignal;
137 }
138 case LTTNG_CONSUMER_ADD_STREAM:
139 {
140 int fd;
141 struct consumer_relayd_sock_pair *relayd = NULL;
142 struct lttng_consumer_stream *new_stream;
143
144 /* block */
145 if (lttng_consumer_poll_socket(consumer_sockpoll) < 0) {
146 rcu_read_unlock();
147 return -EINTR;
148 }
149
150 /* Get stream file descriptor from socket */
151 ret = lttcomm_recv_fds_unix_sock(sock, &fd, 1);
152 if (ret != sizeof(fd)) {
153 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_ERROR_RECV_FD);
154 rcu_read_unlock();
155 return ret;
156 }
157
158 new_stream = consumer_allocate_stream(msg.u.stream.channel_key,
159 msg.u.stream.stream_key,
160 fd, fd,
161 msg.u.stream.state,
162 msg.u.stream.mmap_len,
163 msg.u.stream.output,
164 msg.u.stream.path_name,
165 msg.u.stream.uid,
166 msg.u.stream.gid,
167 msg.u.stream.net_index,
168 msg.u.stream.metadata_flag);
169 if (new_stream == NULL) {
170 lttng_consumer_send_error(ctx, LTTCOMM_CONSUMERD_OUTFD_ERROR);
171 goto end_nosignal;
172 }
173
174 /*
175 * The buffer flush is done on the session daemon side for the kernel
176 * so no need for the stream "hangup_flush_done" variable to be
177 * tracked. This is important for a kernel stream since we don't rely
178 * on the flush state of the stream to read data. It's not the case for
179 * user space tracing.
180 */
181 new_stream->hangup_flush_done = 0;
182
183 /* The stream is not metadata. Get relayd reference if exists. */
184 relayd = consumer_find_relayd(msg.u.stream.net_index);
185 if (relayd != NULL) {
186 /* Add stream on the relayd */
187 pthread_mutex_lock(&relayd->ctrl_sock_mutex);
188 ret = relayd_add_stream(&relayd->control_sock,
189 msg.u.stream.name, msg.u.stream.path_name,
190 &new_stream->relayd_stream_id);
191 pthread_mutex_unlock(&relayd->ctrl_sock_mutex);
192 if (ret < 0) {
193 goto end_nosignal;
194 }
195 } else if (msg.u.stream.net_index != -1) {
196 ERR("Network sequence index %d unknown. Not adding stream.",
197 msg.u.stream.net_index);
198 free(new_stream);
199 goto end_nosignal;
200 }
201
202 /* Send stream to the metadata thread */
203 if (new_stream->metadata_flag) {
204 if (ctx->on_recv_stream) {
205 ret = ctx->on_recv_stream(new_stream);
206 if (ret < 0) {
207 goto end_nosignal;
208 }
209 }
210
211 do {
212 ret = write(ctx->consumer_metadata_pipe[1], new_stream,
213 sizeof(struct lttng_consumer_stream));
214 } while (ret < 0 && errno == EINTR);
215 if (ret < 0) {
216 PERROR("write metadata pipe");
217 }
218 } else {
219 if (ctx->on_recv_stream) {
220 ret = ctx->on_recv_stream(new_stream);
221 if (ret < 0) {
222 goto end_nosignal;
223 }
224 }
225 consumer_add_stream(new_stream);
226 }
227
228 DBG("Kernel consumer_add_stream (%d)", fd);
229 break;
230 }
231 case LTTNG_CONSUMER_UPDATE_STREAM:
232 {
233 rcu_read_unlock();
234 return -ENOSYS;
235 }
236 case LTTNG_CONSUMER_DESTROY_RELAYD:
237 {
238 uint64_t index = msg.u.destroy_relayd.net_seq_idx;
239 struct consumer_relayd_sock_pair *relayd;
240
241 DBG("Kernel consumer destroying relayd %" PRIu64, index);
242
243 /* Get relayd reference if exists. */
244 relayd = consumer_find_relayd(index);
245 if (relayd == NULL) {
246 ERR("Unable to find relayd %" PRIu64, index);
247 goto end_nosignal;
248 }
249
250 /*
251 * Each relayd socket pair has a refcount of stream attached to it
252 * which tells if the relayd is still active or not depending on the
253 * refcount value.
254 *
255 * This will set the destroy flag of the relayd object and destroy it
256 * if the refcount reaches zero when called.
257 *
258 * The destroy can happen either here or when a stream fd hangs up.
259 */
260 consumer_flag_relayd_for_destroy(relayd);
261
262 goto end_nosignal;
263 }
264 default:
265 goto end_nosignal;
266 }
267
268 /*
269 * Wake-up the other end by writing a null byte in the pipe (non-blocking).
270 * Important note: Because writing into the pipe is non-blocking (and
271 * therefore we allow dropping wakeup data, as long as there is wakeup data
272 * present in the pipe buffer to wake up the other end), the other end
273 * should perform the following sequence for waiting:
274 *
275 * 1) empty the pipe (reads).
276 * 2) perform update operation.
277 * 3) wait on the pipe (poll).
278 */
279 do {
280 ret = write(ctx->consumer_poll_pipe[1], "", 1);
281 } while (ret < 0 && errno == EINTR);
282 end_nosignal:
283 rcu_read_unlock();
284
285 /*
286 * Return 1 to indicate success since the 0 value can be a socket
287 * shutdown during the recv() or send() call.
288 */
289 return 1;
290 }
291
292 /*
293 * Consume data on a file descriptor and write it on a trace file.
294 */
295 ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
296 struct lttng_consumer_local_data *ctx)
297 {
298 unsigned long len, subbuf_size, padding;
299 int err;
300 ssize_t ret = 0;
301 int infd = stream->wait_fd;
302
303 DBG("In read_subbuffer (infd : %d)", infd);
304 /* Get the next subbuffer */
305 err = kernctl_get_next_subbuf(infd);
306 if (err != 0) {
307 ret = err;
308 /*
309 * This is a debug message even for single-threaded consumer,
310 * because poll() have more relaxed criterions than get subbuf,
311 * so get_subbuf may fail for short race windows where poll()
312 * would issue wakeups.
313 */
314 DBG("Reserving sub buffer failed (everything is normal, "
315 "it is due to concurrency)");
316 goto end;
317 }
318
319 /* Get the full subbuffer size including padding */
320 err = kernctl_get_padded_subbuf_size(infd, &len);
321 if (err != 0) {
322 errno = -err;
323 perror("Getting sub-buffer len failed.");
324 ret = err;
325 goto end;
326 }
327
328 switch (stream->output) {
329 case LTTNG_EVENT_SPLICE:
330
331 /*
332 * XXX: The lttng-modules splice "actor" does not handle copying
333 * partial pages hence only using the subbuffer size without the
334 * padding makes the splice fail.
335 */
336 subbuf_size = len;
337 padding = 0;
338
339 /* splice the subbuffer to the tracefile */
340 ret = lttng_consumer_on_read_subbuffer_splice(ctx, stream, subbuf_size,
341 padding);
342 /*
343 * XXX: Splice does not support network streaming so the return value
344 * is simply checked against subbuf_size and not like the mmap() op.
345 */
346 if (ret != subbuf_size) {
347 /*
348 * display the error but continue processing to try
349 * to release the subbuffer
350 */
351 ERR("Error splicing to tracefile (ret: %zd != len: %lu)",
352 ret, subbuf_size);
353 }
354 break;
355 case LTTNG_EVENT_MMAP:
356 /* Get subbuffer size without padding */
357 err = kernctl_get_subbuf_size(infd, &subbuf_size);
358 if (err != 0) {
359 errno = -err;
360 perror("Getting sub-buffer len failed.");
361 ret = err;
362 goto end;
363 }
364
365 /* Make sure the tracer is not gone mad on us! */
366 assert(len >= subbuf_size);
367
368 padding = len - subbuf_size;
369
370 /* write the subbuffer to the tracefile */
371 ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, subbuf_size,
372 padding);
373 /*
374 * The mmap operation should write subbuf_size amount of data when
375 * network streaming or the full padding (len) size when we are _not_
376 * streaming.
377 */
378 if ((ret != subbuf_size && stream->net_seq_idx != -1) ||
379 (ret != len && stream->net_seq_idx == -1)) {
380 /*
381 * Display the error but continue processing to try to release the
382 * subbuffer
383 */
384 ERR("Error writing to tracefile "
385 "(ret: %zd != len: %lu != subbuf_size: %lu)",
386 ret, len, subbuf_size);
387 }
388 break;
389 default:
390 ERR("Unknown output method");
391 ret = -1;
392 }
393
394 err = kernctl_put_next_subbuf(infd);
395 if (err != 0) {
396 errno = -err;
397 if (errno == EFAULT) {
398 perror("Error in unreserving sub buffer\n");
399 } else if (errno == EIO) {
400 /* Should never happen with newer LTTng versions */
401 perror("Reader has been pushed by the writer, last sub-buffer corrupted.");
402 }
403
404 ret = -err;
405 goto end;
406 }
407
408 end:
409 return ret;
410 }
411
412 int lttng_kconsumer_on_recv_stream(struct lttng_consumer_stream *stream)
413 {
414 int ret;
415
416 /* Opening the tracefile in write mode */
417 if (strlen(stream->path_name) > 0 && stream->net_seq_idx == -1) {
418 ret = run_as_open(stream->path_name,
419 O_WRONLY|O_CREAT|O_TRUNC,
420 S_IRWXU|S_IRWXG|S_IRWXO,
421 stream->uid, stream->gid);
422 if (ret < 0) {
423 ERR("Opening %s", stream->path_name);
424 perror("open");
425 goto error;
426 }
427 stream->out_fd = ret;
428 }
429
430 if (stream->output == LTTNG_EVENT_MMAP) {
431 /* get the len of the mmap region */
432 unsigned long mmap_len;
433
434 ret = kernctl_get_mmap_len(stream->wait_fd, &mmap_len);
435 if (ret != 0) {
436 errno = -ret;
437 perror("kernctl_get_mmap_len");
438 goto error_close_fd;
439 }
440 stream->mmap_len = (size_t) mmap_len;
441
442 stream->mmap_base = mmap(NULL, stream->mmap_len,
443 PROT_READ, MAP_PRIVATE, stream->wait_fd, 0);
444 if (stream->mmap_base == MAP_FAILED) {
445 perror("Error mmaping");
446 ret = -1;
447 goto error_close_fd;
448 }
449 }
450
451 /* we return 0 to let the library handle the FD internally */
452 return 0;
453
454 error_close_fd:
455 {
456 int err;
457
458 err = close(stream->out_fd);
459 assert(!err);
460 }
461 error:
462 return ret;
463 }
464
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