9464a84f088ebd285cde162819e620741e5a2e92
[lttng-tools.git] / src / bin / lttng-sessiond / kernel.c
1 /*
2 * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License, version 2 only,
6 * as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public License along
14 * with this program; if not, write to the Free Software Foundation, Inc.,
15 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
16 */
17
18 #define _GNU_SOURCE
19 #define _LGPL_SOURCE
20 #include <errno.h>
21 #include <fcntl.h>
22 #include <stdlib.h>
23 #include <stdio.h>
24 #include <string.h>
25 #include <unistd.h>
26 #include <inttypes.h>
27
28 #include <common/common.h>
29 #include <common/kernel-ctl/kernel-ctl.h>
30 #include <common/kernel-ctl/kernel-ioctl.h>
31 #include <common/sessiond-comm/sessiond-comm.h>
32
33 #include "consumer.h"
34 #include "kernel.h"
35 #include "kernel-consumer.h"
36 #include "kern-modules.h"
37 #include "utils.h"
38
39 /*
40 * Add context on a kernel channel.
41 */
42 int kernel_add_channel_context(struct ltt_kernel_channel *chan,
43 struct ltt_kernel_context *ctx)
44 {
45 int ret;
46
47 assert(chan);
48 assert(ctx);
49
50 DBG("Adding context to channel %s", chan->channel->name);
51 ret = kernctl_add_context(chan->fd, &ctx->ctx);
52 if (ret < 0) {
53 if (errno != EEXIST) {
54 PERROR("add context ioctl");
55 } else {
56 /* If EEXIST, we just ignore the error */
57 ret = 0;
58 }
59 goto error;
60 }
61
62 cds_list_add_tail(&ctx->list, &chan->ctx_list);
63
64 return 0;
65
66 error:
67 return ret;
68 }
69
70 /*
71 * Create a new kernel session, register it to the kernel tracer and add it to
72 * the session daemon session.
73 */
74 int kernel_create_session(struct ltt_session *session, int tracer_fd)
75 {
76 int ret;
77 struct ltt_kernel_session *lks;
78
79 assert(session);
80
81 /* Allocate data structure */
82 lks = trace_kernel_create_session();
83 if (lks == NULL) {
84 ret = -1;
85 goto error;
86 }
87
88 /* Kernel tracer session creation */
89 ret = kernctl_create_session(tracer_fd);
90 if (ret < 0) {
91 PERROR("ioctl kernel create session");
92 goto error;
93 }
94
95 lks->fd = ret;
96 /* Prevent fd duplication after execlp() */
97 ret = fcntl(lks->fd, F_SETFD, FD_CLOEXEC);
98 if (ret < 0) {
99 PERROR("fcntl session fd");
100 }
101
102 lks->id = session->id;
103 lks->consumer_fds_sent = 0;
104 session->kernel_session = lks;
105
106 DBG("Kernel session created (fd: %d)", lks->fd);
107
108 return 0;
109
110 error:
111 if (lks) {
112 trace_kernel_destroy_session(lks);
113 }
114 return ret;
115 }
116
117 /*
118 * Create a kernel channel, register it to the kernel tracer and add it to the
119 * kernel session.
120 */
121 int kernel_create_channel(struct ltt_kernel_session *session,
122 struct lttng_channel *chan)
123 {
124 int ret;
125 struct ltt_kernel_channel *lkc;
126
127 assert(session);
128 assert(chan);
129
130 /* Allocate kernel channel */
131 lkc = trace_kernel_create_channel(chan);
132 if (lkc == NULL) {
133 goto error;
134 }
135
136 DBG3("Kernel create channel %s with attr: %d, %" PRIu64 ", %" PRIu64 ", %u, %u, %d, %d",
137 chan->name, lkc->channel->attr.overwrite,
138 lkc->channel->attr.subbuf_size, lkc->channel->attr.num_subbuf,
139 lkc->channel->attr.switch_timer_interval, lkc->channel->attr.read_timer_interval,
140 lkc->channel->attr.live_timer_interval, lkc->channel->attr.output);
141
142 /* Kernel tracer channel creation */
143 ret = kernctl_create_channel(session->fd, &lkc->channel->attr);
144 if (ret < 0) {
145 PERROR("ioctl kernel create channel");
146 goto error;
147 }
148
149 /* Setup the channel fd */
150 lkc->fd = ret;
151 /* Prevent fd duplication after execlp() */
152 ret = fcntl(lkc->fd, F_SETFD, FD_CLOEXEC);
153 if (ret < 0) {
154 PERROR("fcntl session fd");
155 }
156
157 /* Add channel to session */
158 cds_list_add(&lkc->list, &session->channel_list.head);
159 session->channel_count++;
160 lkc->session = session;
161
162 DBG("Kernel channel %s created (fd: %d)", lkc->channel->name, lkc->fd);
163
164 return 0;
165
166 error:
167 if (lkc) {
168 free(lkc->channel);
169 free(lkc);
170 }
171 return -1;
172 }
173
174 /*
175 * Create a kernel event, enable it to the kernel tracer and add it to the
176 * channel event list of the kernel session.
177 * We own filter_expression and filter.
178 */
179 int kernel_create_event(struct lttng_event *ev,
180 struct ltt_kernel_channel *channel)
181 {
182 int ret;
183 struct ltt_kernel_event *event;
184
185 assert(ev);
186 assert(channel);
187
188 event = trace_kernel_create_event(ev);
189 if (event == NULL) {
190 ret = -1;
191 goto error;
192 }
193
194 ret = kernctl_create_event(channel->fd, event->event);
195 if (ret < 0) {
196 switch (errno) {
197 case EEXIST:
198 break;
199 case ENOSYS:
200 WARN("Event type not implemented");
201 break;
202 case ENOENT:
203 WARN("Event %s not found!", ev->name);
204 break;
205 default:
206 PERROR("create event ioctl");
207 }
208 ret = -errno;
209 goto free_event;
210 }
211
212 /*
213 * LTTNG_KERNEL_SYSCALL event creation will return 0 on success.
214 */
215 if (ret == 0 && event->event->instrumentation == LTTNG_KERNEL_SYSCALL) {
216 DBG2("Kernel event syscall creation success");
217 /*
218 * We use fd == -1 to ensure that we never trigger a close of fd
219 * 0.
220 */
221 event->fd = -1;
222 goto add_list;
223 }
224
225 event->fd = ret;
226 /* Prevent fd duplication after execlp() */
227 ret = fcntl(event->fd, F_SETFD, FD_CLOEXEC);
228 if (ret < 0) {
229 PERROR("fcntl session fd");
230 }
231
232 add_list:
233 /* Add event to event list */
234 cds_list_add(&event->list, &channel->events_list.head);
235 channel->event_count++;
236
237 DBG("Event %s created (fd: %d)", ev->name, event->fd);
238
239 return 0;
240
241 free_event:
242 free(event);
243 error:
244 return ret;
245 }
246
247 /*
248 * Disable a kernel channel.
249 */
250 int kernel_disable_channel(struct ltt_kernel_channel *chan)
251 {
252 int ret;
253
254 assert(chan);
255
256 ret = kernctl_disable(chan->fd);
257 if (ret < 0) {
258 PERROR("disable chan ioctl");
259 ret = errno;
260 goto error;
261 }
262
263 chan->enabled = 0;
264 DBG("Kernel channel %s disabled (fd: %d)", chan->channel->name, chan->fd);
265
266 return 0;
267
268 error:
269 return ret;
270 }
271
272 /*
273 * Enable a kernel channel.
274 */
275 int kernel_enable_channel(struct ltt_kernel_channel *chan)
276 {
277 int ret;
278
279 assert(chan);
280
281 ret = kernctl_enable(chan->fd);
282 if (ret < 0 && errno != EEXIST) {
283 PERROR("Enable kernel chan");
284 goto error;
285 }
286
287 chan->enabled = 1;
288 DBG("Kernel channel %s enabled (fd: %d)", chan->channel->name, chan->fd);
289
290 return 0;
291
292 error:
293 return ret;
294 }
295
296 /*
297 * Enable a kernel event.
298 */
299 int kernel_enable_event(struct ltt_kernel_event *event)
300 {
301 int ret;
302
303 assert(event);
304
305 ret = kernctl_enable(event->fd);
306 if (ret < 0) {
307 switch (errno) {
308 case EEXIST:
309 ret = LTTNG_ERR_KERN_EVENT_EXIST;
310 break;
311 default:
312 PERROR("enable kernel event");
313 break;
314 }
315 goto error;
316 }
317
318 event->enabled = 1;
319 DBG("Kernel event %s enabled (fd: %d)", event->event->name, event->fd);
320
321 return 0;
322
323 error:
324 return ret;
325 }
326
327 /*
328 * Disable a kernel event.
329 */
330 int kernel_disable_event(struct ltt_kernel_event *event)
331 {
332 int ret;
333
334 assert(event);
335
336 ret = kernctl_disable(event->fd);
337 if (ret < 0) {
338 switch (errno) {
339 case EEXIST:
340 ret = LTTNG_ERR_KERN_EVENT_EXIST;
341 break;
342 default:
343 PERROR("disable kernel event");
344 break;
345 }
346 goto error;
347 }
348
349 event->enabled = 0;
350 DBG("Kernel event %s disabled (fd: %d)", event->event->name, event->fd);
351
352 return 0;
353
354 error:
355 return ret;
356 }
357
358 int kernel_enable_syscall(const char *syscall_name,
359 struct ltt_kernel_channel *channel)
360 {
361 return kernctl_enable_syscall(channel->fd, syscall_name);
362 }
363
364 int kernel_disable_syscall(const char *syscall_name,
365 struct ltt_kernel_channel *channel)
366 {
367 return kernctl_disable_syscall(channel->fd, syscall_name);
368 }
369
370 /*
371 * Create kernel metadata, open from the kernel tracer and add it to the
372 * kernel session.
373 */
374 int kernel_open_metadata(struct ltt_kernel_session *session)
375 {
376 int ret;
377 struct ltt_kernel_metadata *lkm = NULL;
378
379 assert(session);
380
381 /* Allocate kernel metadata */
382 lkm = trace_kernel_create_metadata();
383 if (lkm == NULL) {
384 goto error;
385 }
386
387 /* Kernel tracer metadata creation */
388 ret = kernctl_open_metadata(session->fd, &lkm->conf->attr);
389 if (ret < 0) {
390 goto error_open;
391 }
392
393 lkm->fd = ret;
394 /* Prevent fd duplication after execlp() */
395 ret = fcntl(lkm->fd, F_SETFD, FD_CLOEXEC);
396 if (ret < 0) {
397 PERROR("fcntl session fd");
398 }
399
400 session->metadata = lkm;
401
402 DBG("Kernel metadata opened (fd: %d)", lkm->fd);
403
404 return 0;
405
406 error_open:
407 trace_kernel_destroy_metadata(lkm);
408 error:
409 return -1;
410 }
411
412 /*
413 * Start tracing session.
414 */
415 int kernel_start_session(struct ltt_kernel_session *session)
416 {
417 int ret;
418
419 assert(session);
420
421 ret = kernctl_start_session(session->fd);
422 if (ret < 0) {
423 PERROR("ioctl start session");
424 goto error;
425 }
426
427 DBG("Kernel session started");
428
429 return 0;
430
431 error:
432 return ret;
433 }
434
435 /*
436 * Make a kernel wait to make sure in-flight probe have completed.
437 */
438 void kernel_wait_quiescent(int fd)
439 {
440 int ret;
441
442 DBG("Kernel quiescent wait on %d", fd);
443
444 ret = kernctl_wait_quiescent(fd);
445 if (ret < 0) {
446 PERROR("wait quiescent ioctl");
447 ERR("Kernel quiescent wait failed");
448 }
449 }
450
451 /*
452 * Kernel calibrate
453 */
454 int kernel_calibrate(int fd, struct lttng_kernel_calibrate *calibrate)
455 {
456 int ret;
457
458 assert(calibrate);
459
460 ret = kernctl_calibrate(fd, calibrate);
461 if (ret < 0) {
462 PERROR("calibrate ioctl");
463 return -1;
464 }
465
466 return 0;
467 }
468
469
470 /*
471 * Force flush buffer of metadata.
472 */
473 int kernel_metadata_flush_buffer(int fd)
474 {
475 int ret;
476
477 DBG("Kernel flushing metadata buffer on fd %d", fd);
478
479 ret = kernctl_buffer_flush(fd);
480 if (ret < 0) {
481 ERR("Fail to flush metadata buffers %d (ret: %d)", fd, ret);
482 }
483
484 return 0;
485 }
486
487 /*
488 * Force flush buffer for channel.
489 */
490 int kernel_flush_buffer(struct ltt_kernel_channel *channel)
491 {
492 int ret;
493 struct ltt_kernel_stream *stream;
494
495 assert(channel);
496
497 DBG("Flush buffer for channel %s", channel->channel->name);
498
499 cds_list_for_each_entry(stream, &channel->stream_list.head, list) {
500 DBG("Flushing channel stream %d", stream->fd);
501 ret = kernctl_buffer_flush(stream->fd);
502 if (ret < 0) {
503 PERROR("ioctl");
504 ERR("Fail to flush buffer for stream %d (ret: %d)",
505 stream->fd, ret);
506 }
507 }
508
509 return 0;
510 }
511
512 /*
513 * Stop tracing session.
514 */
515 int kernel_stop_session(struct ltt_kernel_session *session)
516 {
517 int ret;
518
519 assert(session);
520
521 ret = kernctl_stop_session(session->fd);
522 if (ret < 0) {
523 goto error;
524 }
525
526 DBG("Kernel session stopped");
527
528 return 0;
529
530 error:
531 return ret;
532 }
533
534 /*
535 * Open stream of channel, register it to the kernel tracer and add it
536 * to the stream list of the channel.
537 *
538 * Return the number of created stream. Else, a negative value.
539 */
540 int kernel_open_channel_stream(struct ltt_kernel_channel *channel)
541 {
542 int ret, count = 0;
543 struct ltt_kernel_stream *lks;
544
545 assert(channel);
546
547 while ((ret = kernctl_create_stream(channel->fd)) >= 0) {
548 lks = trace_kernel_create_stream(channel->channel->name, count);
549 if (lks == NULL) {
550 ret = close(ret);
551 if (ret) {
552 PERROR("close");
553 }
554 goto error;
555 }
556
557 lks->fd = ret;
558 /* Prevent fd duplication after execlp() */
559 ret = fcntl(lks->fd, F_SETFD, FD_CLOEXEC);
560 if (ret < 0) {
561 PERROR("fcntl session fd");
562 }
563
564 lks->tracefile_size = channel->channel->attr.tracefile_size;
565 lks->tracefile_count = channel->channel->attr.tracefile_count;
566
567 /* Add stream to channe stream list */
568 cds_list_add(&lks->list, &channel->stream_list.head);
569 channel->stream_count++;
570
571 /* Increment counter which represent CPU number. */
572 count++;
573
574 DBG("Kernel stream %s created (fd: %d, state: %d)", lks->name, lks->fd,
575 lks->state);
576 }
577
578 return channel->stream_count;
579
580 error:
581 return -1;
582 }
583
584 /*
585 * Open the metadata stream and set it to the kernel session.
586 */
587 int kernel_open_metadata_stream(struct ltt_kernel_session *session)
588 {
589 int ret;
590
591 assert(session);
592
593 ret = kernctl_create_stream(session->metadata->fd);
594 if (ret < 0) {
595 PERROR("kernel create metadata stream");
596 goto error;
597 }
598
599 DBG("Kernel metadata stream created (fd: %d)", ret);
600 session->metadata_stream_fd = ret;
601 /* Prevent fd duplication after execlp() */
602 ret = fcntl(session->metadata_stream_fd, F_SETFD, FD_CLOEXEC);
603 if (ret < 0) {
604 PERROR("fcntl session fd");
605 }
606
607 return 0;
608
609 error:
610 return -1;
611 }
612
613 /*
614 * Get the event list from the kernel tracer and return the number of elements.
615 */
616 ssize_t kernel_list_events(int tracer_fd, struct lttng_event **events)
617 {
618 int fd, ret;
619 char *event;
620 size_t nbmem, count = 0;
621 FILE *fp;
622 struct lttng_event *elist;
623
624 assert(events);
625
626 fd = kernctl_tracepoint_list(tracer_fd);
627 if (fd < 0) {
628 PERROR("kernel tracepoint list");
629 goto error;
630 }
631
632 fp = fdopen(fd, "r");
633 if (fp == NULL) {
634 PERROR("kernel tracepoint list fdopen");
635 goto error_fp;
636 }
637
638 /*
639 * Init memory size counter
640 * See kernel-ctl.h for explanation of this value
641 */
642 nbmem = KERNEL_EVENT_INIT_LIST_SIZE;
643 elist = zmalloc(sizeof(struct lttng_event) * nbmem);
644 if (elist == NULL) {
645 PERROR("alloc list events");
646 count = -ENOMEM;
647 goto end;
648 }
649
650 while (fscanf(fp, "event { name = %m[^;]; };\n", &event) == 1) {
651 if (count >= nbmem) {
652 struct lttng_event *new_elist;
653 size_t new_nbmem;
654
655 new_nbmem = nbmem << 1;
656 DBG("Reallocating event list from %zu to %zu bytes",
657 nbmem, new_nbmem);
658 new_elist = realloc(elist, new_nbmem * sizeof(struct lttng_event));
659 if (new_elist == NULL) {
660 PERROR("realloc list events");
661 free(event);
662 free(elist);
663 count = -ENOMEM;
664 goto end;
665 }
666 /* Zero the new memory */
667 memset(new_elist + nbmem, 0,
668 (new_nbmem - nbmem) * sizeof(struct lttng_event));
669 nbmem = new_nbmem;
670 elist = new_elist;
671 }
672 strncpy(elist[count].name, event, LTTNG_SYMBOL_NAME_LEN);
673 elist[count].name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
674 elist[count].enabled = -1;
675 count++;
676 free(event);
677 }
678
679 *events = elist;
680 DBG("Kernel list events done (%zu events)", count);
681 end:
682 ret = fclose(fp); /* closes both fp and fd */
683 if (ret) {
684 PERROR("fclose");
685 }
686 return count;
687
688 error_fp:
689 ret = close(fd);
690 if (ret) {
691 PERROR("close");
692 }
693 error:
694 return -1;
695 }
696
697 /*
698 * Get kernel version and validate it.
699 */
700 int kernel_validate_version(int tracer_fd)
701 {
702 int ret;
703 struct lttng_kernel_tracer_version version;
704 struct lttng_kernel_tracer_abi_version abi_version;
705
706 ret = kernctl_tracer_version(tracer_fd, &version);
707 if (ret < 0) {
708 ERR("Failed at getting the lttng-modules version");
709 goto error;
710 }
711
712 /* Validate version */
713 if (version.major != VERSION_MAJOR) {
714 ERR("Kernel tracer major version (%d) is not compatible with lttng-tools major version (%d)",
715 version.major, VERSION_MAJOR);
716 goto error_version;
717 }
718 ret = kernctl_tracer_abi_version(tracer_fd, &abi_version);
719 if (ret < 0) {
720 ERR("Failed at getting lttng-modules ABI version");
721 goto error;
722 }
723 if (abi_version.major != LTTNG_MODULES_ABI_MAJOR_VERSION) {
724 ERR("Kernel tracer ABI version (%d.%d) is not compatible with expected ABI major version (%d.*)",
725 abi_version.major, abi_version.minor,
726 LTTNG_MODULES_ABI_MAJOR_VERSION);
727 goto error;
728 }
729 DBG2("Kernel tracer version validated (%d.%d, ABI %d.%d)",
730 version.major, version.minor,
731 abi_version.major, abi_version.minor);
732 return 0;
733
734 error_version:
735 ret = -1;
736
737 error:
738 return ret;
739 }
740
741 /*
742 * Kernel work-arounds called at the start of sessiond main().
743 */
744 int init_kernel_workarounds(void)
745 {
746 int ret;
747 FILE *fp;
748
749 /*
750 * boot_id needs to be read once before being used concurrently
751 * to deal with a Linux kernel race. A fix is proposed for
752 * upstream, but the work-around is needed for older kernels.
753 */
754 fp = fopen("/proc/sys/kernel/random/boot_id", "r");
755 if (!fp) {
756 goto end_boot_id;
757 }
758 while (!feof(fp)) {
759 char buf[37] = "";
760
761 ret = fread(buf, 1, sizeof(buf), fp);
762 if (ret < 0) {
763 /* Ignore error, we don't really care */
764 }
765 }
766 ret = fclose(fp);
767 if (ret) {
768 PERROR("fclose");
769 }
770 end_boot_id:
771 return 0;
772 }
773
774 /*
775 * Complete teardown of a kernel session.
776 */
777 void kernel_destroy_session(struct ltt_kernel_session *ksess)
778 {
779 if (ksess == NULL) {
780 DBG3("No kernel session when tearing down session");
781 return;
782 }
783
784 DBG("Tearing down kernel session");
785
786 /*
787 * Destroy channels on the consumer if at least one FD has been sent and we
788 * are in no output mode because the streams are in *no* monitor mode so we
789 * have to send a command to clean them up or else they leaked.
790 */
791 if (!ksess->output_traces && ksess->consumer_fds_sent) {
792 int ret;
793 struct consumer_socket *socket;
794 struct lttng_ht_iter iter;
795
796 /* For each consumer socket. */
797 rcu_read_lock();
798 cds_lfht_for_each_entry(ksess->consumer->socks->ht, &iter.iter,
799 socket, node.node) {
800 struct ltt_kernel_channel *chan;
801
802 /* For each channel, ask the consumer to destroy it. */
803 cds_list_for_each_entry(chan, &ksess->channel_list.head, list) {
804 ret = kernel_consumer_destroy_channel(socket, chan);
805 if (ret < 0) {
806 /* Consumer is probably dead. Use next socket. */
807 continue;
808 }
809 }
810 }
811 rcu_read_unlock();
812 }
813
814 /* Close any relayd session */
815 consumer_output_send_destroy_relayd(ksess->consumer);
816
817 trace_kernel_destroy_session(ksess);
818 }
819
820 /*
821 * Destroy a kernel channel object. It does not do anything on the tracer side.
822 */
823 void kernel_destroy_channel(struct ltt_kernel_channel *kchan)
824 {
825 struct ltt_kernel_session *ksess = NULL;
826
827 assert(kchan);
828 assert(kchan->channel);
829
830 DBG3("Kernel destroy channel %s", kchan->channel->name);
831
832 /* Update channel count of associated session. */
833 if (kchan->session) {
834 /* Keep pointer reference so we can update it after the destroy. */
835 ksess = kchan->session;
836 }
837
838 trace_kernel_destroy_channel(kchan);
839
840 /*
841 * At this point the kernel channel is not visible anymore. This is safe
842 * since in order to work on a visible kernel session, the tracing session
843 * lock (ltt_session.lock) MUST be acquired.
844 */
845 if (ksess) {
846 ksess->channel_count--;
847 }
848 }
849
850 /*
851 * Take a snapshot for a given kernel session.
852 *
853 * Return 0 on success or else return a LTTNG_ERR code.
854 */
855 int kernel_snapshot_record(struct ltt_kernel_session *ksess,
856 struct snapshot_output *output, int wait,
857 uint64_t nb_packets_per_stream)
858 {
859 int err, ret, saved_metadata_fd;
860 struct consumer_socket *socket;
861 struct lttng_ht_iter iter;
862 struct ltt_kernel_metadata *saved_metadata;
863
864 assert(ksess);
865 assert(ksess->consumer);
866 assert(output);
867
868 DBG("Kernel snapshot record started");
869
870 /* Save current metadata since the following calls will change it. */
871 saved_metadata = ksess->metadata;
872 saved_metadata_fd = ksess->metadata_stream_fd;
873
874 rcu_read_lock();
875
876 ret = kernel_open_metadata(ksess);
877 if (ret < 0) {
878 ret = LTTNG_ERR_KERN_META_FAIL;
879 goto error;
880 }
881
882 ret = kernel_open_metadata_stream(ksess);
883 if (ret < 0) {
884 ret = LTTNG_ERR_KERN_META_FAIL;
885 goto error_open_stream;
886 }
887
888 /* Send metadata to consumer and snapshot everything. */
889 cds_lfht_for_each_entry(ksess->consumer->socks->ht, &iter.iter,
890 socket, node.node) {
891 struct consumer_output *saved_output;
892 struct ltt_kernel_channel *chan;
893
894 /*
895 * Temporarly switch consumer output for our snapshot output. As long
896 * as the session lock is taken, this is safe.
897 */
898 saved_output = ksess->consumer;
899 ksess->consumer = output->consumer;
900
901 pthread_mutex_lock(socket->lock);
902 /* This stream must not be monitored by the consumer. */
903 ret = kernel_consumer_add_metadata(socket, ksess, 0);
904 pthread_mutex_unlock(socket->lock);
905 /* Put back the saved consumer output into the session. */
906 ksess->consumer = saved_output;
907 if (ret < 0) {
908 ret = LTTNG_ERR_KERN_CONSUMER_FAIL;
909 goto error_consumer;
910 }
911
912 /* For each channel, ask the consumer to snapshot it. */
913 cds_list_for_each_entry(chan, &ksess->channel_list.head, list) {
914 pthread_mutex_lock(socket->lock);
915 ret = consumer_snapshot_channel(socket, chan->fd, output, 0,
916 ksess->uid, ksess->gid,
917 DEFAULT_KERNEL_TRACE_DIR, wait,
918 nb_packets_per_stream);
919 pthread_mutex_unlock(socket->lock);
920 if (ret < 0) {
921 ret = LTTNG_ERR_KERN_CONSUMER_FAIL;
922 (void) kernel_consumer_destroy_metadata(socket,
923 ksess->metadata);
924 goto error_consumer;
925 }
926 }
927
928 /* Snapshot metadata, */
929 pthread_mutex_lock(socket->lock);
930 ret = consumer_snapshot_channel(socket, ksess->metadata->fd, output,
931 1, ksess->uid, ksess->gid,
932 DEFAULT_KERNEL_TRACE_DIR, wait, 0);
933 pthread_mutex_unlock(socket->lock);
934 if (ret < 0) {
935 ret = LTTNG_ERR_KERN_CONSUMER_FAIL;
936 goto error_consumer;
937 }
938
939 /*
940 * The metadata snapshot is done, ask the consumer to destroy it since
941 * it's not monitored on the consumer side.
942 */
943 (void) kernel_consumer_destroy_metadata(socket, ksess->metadata);
944 }
945
946 ret = LTTNG_OK;
947
948 error_consumer:
949 /* Close newly opened metadata stream. It's now on the consumer side. */
950 err = close(ksess->metadata_stream_fd);
951 if (err < 0) {
952 PERROR("close snapshot kernel");
953 }
954
955 error_open_stream:
956 trace_kernel_destroy_metadata(ksess->metadata);
957 error:
958 /* Restore metadata state.*/
959 ksess->metadata = saved_metadata;
960 ksess->metadata_stream_fd = saved_metadata_fd;
961
962 rcu_read_unlock();
963 return ret;
964 }
965
966 /*
967 * Get the syscall mask array from the kernel tracer.
968 *
969 * Return 0 on success else a negative value. In both case, syscall_mask should
970 * be freed.
971 */
972 int kernel_syscall_mask(int chan_fd, char **syscall_mask, uint32_t *nr_bits)
973 {
974 assert(syscall_mask);
975 assert(nr_bits);
976
977 return kernctl_syscall_mask(chan_fd, syscall_mask, nr_bits);
978 }
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