Fix: sessiond: check for lttng-modules ABI 2.1 rather than 2.8
[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 _LGPL_SOURCE
19 #include <fcntl.h>
20 #include <stdlib.h>
21 #include <stdio.h>
22 #include <string.h>
23 #include <unistd.h>
24 #include <inttypes.h>
25 #include <sys/types.h>
26
27 #include <common/common.h>
28 #include <common/trace-chunk.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 "lttng-sessiond.h"
34 #include "lttng-syscall.h"
35 #include "consumer.h"
36 #include "kernel.h"
37 #include "kernel-consumer.h"
38 #include "kern-modules.h"
39 #include "utils.h"
40 #include "rotate.h"
41 #include "modprobe.h"
42
43 /*
44 * Key used to reference a channel between the sessiond and the consumer. This
45 * is only read and updated with the session_list lock held.
46 */
47 static uint64_t next_kernel_channel_key;
48
49 static const char *module_proc_lttng = "/proc/lttng";
50
51 static int kernel_tracer_fd = -1;
52
53 #include <lttng/userspace-probe.h>
54 #include <lttng/userspace-probe-internal.h>
55 /*
56 * Add context on a kernel channel.
57 *
58 * Assumes the ownership of ctx.
59 */
60 int kernel_add_channel_context(struct ltt_kernel_channel *chan,
61 struct ltt_kernel_context *ctx)
62 {
63 int ret;
64
65 assert(chan);
66 assert(ctx);
67
68 DBG("Adding context to channel %s", chan->channel->name);
69 ret = kernctl_add_context(chan->fd, &ctx->ctx);
70 if (ret < 0) {
71 switch (-ret) {
72 case ENOSYS:
73 /* Exists but not available for this kernel */
74 ret = LTTNG_ERR_KERN_CONTEXT_UNAVAILABLE;
75 goto error;
76 case EEXIST:
77 /* If EEXIST, we just ignore the error */
78 ret = 0;
79 goto end;
80 default:
81 PERROR("add context ioctl");
82 ret = LTTNG_ERR_KERN_CONTEXT_FAIL;
83 goto error;
84 }
85 }
86 ret = 0;
87
88 end:
89 cds_list_add_tail(&ctx->list, &chan->ctx_list);
90 ctx->in_list = true;
91 ctx = NULL;
92 error:
93 if (ctx) {
94 trace_kernel_destroy_context(ctx);
95 }
96 return ret;
97 }
98
99 /*
100 * Create a new kernel session, register it to the kernel tracer and add it to
101 * the session daemon session.
102 */
103 int kernel_create_session(struct ltt_session *session)
104 {
105 int ret;
106 struct ltt_kernel_session *lks;
107
108 assert(session);
109
110 /* Allocate data structure */
111 lks = trace_kernel_create_session();
112 if (lks == NULL) {
113 ret = -1;
114 goto error;
115 }
116
117 /* Kernel tracer session creation */
118 ret = kernctl_create_session(kernel_tracer_fd);
119 if (ret < 0) {
120 PERROR("ioctl kernel create session");
121 goto error;
122 }
123
124 lks->fd = ret;
125 /* Prevent fd duplication after execlp() */
126 ret = fcntl(lks->fd, F_SETFD, FD_CLOEXEC);
127 if (ret < 0) {
128 PERROR("fcntl session fd");
129 }
130
131 lks->id = session->id;
132 lks->consumer_fds_sent = 0;
133 session->kernel_session = lks;
134
135 DBG("Kernel session created (fd: %d)", lks->fd);
136
137 /*
138 * This is necessary since the creation time is present in the session
139 * name when it is generated.
140 */
141 if (session->has_auto_generated_name) {
142 ret = kernctl_session_set_name(lks->fd, DEFAULT_SESSION_NAME);
143 } else {
144 ret = kernctl_session_set_name(lks->fd, session->name);
145 }
146 if (ret) {
147 WARN("Could not set kernel session name for session %" PRIu64 " name: %s",
148 session->id, session->name);
149 }
150
151 ret = kernctl_session_set_creation_time(lks->fd, session->creation_time);
152 if (ret) {
153 WARN("Could not set kernel session creation time for session %" PRIu64 " name: %s",
154 session->id, session->name);
155 }
156
157 return 0;
158
159 error:
160 if (lks) {
161 trace_kernel_destroy_session(lks);
162 trace_kernel_free_session(lks);
163 }
164 return ret;
165 }
166
167 /*
168 * Create a kernel channel, register it to the kernel tracer and add it to the
169 * kernel session.
170 */
171 int kernel_create_channel(struct ltt_kernel_session *session,
172 struct lttng_channel *chan)
173 {
174 int ret;
175 struct ltt_kernel_channel *lkc;
176
177 assert(session);
178 assert(chan);
179
180 /* Allocate kernel channel */
181 lkc = trace_kernel_create_channel(chan);
182 if (lkc == NULL) {
183 goto error;
184 }
185
186 DBG3("Kernel create channel %s with attr: %d, %" PRIu64 ", %" PRIu64 ", %u, %u, %d, %d",
187 chan->name, lkc->channel->attr.overwrite,
188 lkc->channel->attr.subbuf_size, lkc->channel->attr.num_subbuf,
189 lkc->channel->attr.switch_timer_interval, lkc->channel->attr.read_timer_interval,
190 lkc->channel->attr.live_timer_interval, lkc->channel->attr.output);
191
192 /* Kernel tracer channel creation */
193 ret = kernctl_create_channel(session->fd, &lkc->channel->attr);
194 if (ret < 0) {
195 PERROR("ioctl kernel create channel");
196 goto error;
197 }
198
199 /* Setup the channel fd */
200 lkc->fd = ret;
201 /* Prevent fd duplication after execlp() */
202 ret = fcntl(lkc->fd, F_SETFD, FD_CLOEXEC);
203 if (ret < 0) {
204 PERROR("fcntl session fd");
205 }
206
207 /* Add channel to session */
208 cds_list_add(&lkc->list, &session->channel_list.head);
209 session->channel_count++;
210 lkc->session = session;
211 lkc->key = ++next_kernel_channel_key;
212
213 DBG("Kernel channel %s created (fd: %d, key: %" PRIu64 ")",
214 lkc->channel->name, lkc->fd, lkc->key);
215
216 return 0;
217
218 error:
219 if (lkc) {
220 free(lkc->channel);
221 free(lkc);
222 }
223 return -1;
224 }
225
226 /*
227 * Compute the offset of the instrumentation byte in the binary based on the
228 * function probe location using the ELF lookup method.
229 *
230 * Returns 0 on success and set the offset out parameter to the offset of the
231 * elf symbol
232 * Returns -1 on error
233 */
234 static
235 int extract_userspace_probe_offset_function_elf(
236 const struct lttng_userspace_probe_location *probe_location,
237 struct ltt_kernel_session *session, uint64_t *offset)
238 {
239 int fd;
240 int ret = 0;
241 const char *symbol = NULL;
242 const struct lttng_userspace_probe_location_lookup_method *lookup = NULL;
243 enum lttng_userspace_probe_location_lookup_method_type lookup_method_type;
244
245 assert(lttng_userspace_probe_location_get_type(probe_location) ==
246 LTTNG_USERSPACE_PROBE_LOCATION_TYPE_FUNCTION);
247
248 lookup = lttng_userspace_probe_location_get_lookup_method(
249 probe_location);
250 if (!lookup) {
251 ret = -1;
252 goto end;
253 }
254
255 lookup_method_type =
256 lttng_userspace_probe_location_lookup_method_get_type(lookup);
257
258 assert(lookup_method_type ==
259 LTTNG_USERSPACE_PROBE_LOCATION_LOOKUP_METHOD_TYPE_FUNCTION_ELF);
260
261 symbol = lttng_userspace_probe_location_function_get_function_name(
262 probe_location);
263 if (!symbol) {
264 ret = -1;
265 goto end;
266 }
267
268 fd = lttng_userspace_probe_location_function_get_binary_fd(probe_location);
269 if (fd < 0) {
270 ret = -1;
271 goto end;
272 }
273
274 ret = run_as_extract_elf_symbol_offset(fd, symbol, session->uid,
275 session->gid, offset);
276 if (ret < 0) {
277 DBG("userspace probe offset calculation failed for "
278 "function %s", symbol);
279 goto end;
280 }
281
282 DBG("userspace probe elf offset for %s is 0x%jd", symbol, (intmax_t)(*offset));
283 end:
284 return ret;
285 }
286
287 /*
288 * Compute the offsets of the instrumentation bytes in the binary based on the
289 * tracepoint probe location using the SDT lookup method. This function
290 * allocates the offsets buffer, the caller must free it.
291 *
292 * Returns 0 on success and set the offset out parameter to the offsets of the
293 * SDT tracepoint.
294 * Returns -1 on error.
295 */
296 static
297 int extract_userspace_probe_offset_tracepoint_sdt(
298 const struct lttng_userspace_probe_location *probe_location,
299 struct ltt_kernel_session *session, uint64_t **offsets,
300 uint32_t *offsets_count)
301 {
302 enum lttng_userspace_probe_location_lookup_method_type lookup_method_type;
303 const struct lttng_userspace_probe_location_lookup_method *lookup = NULL;
304 const char *probe_name = NULL, *provider_name = NULL;
305 int ret = 0;
306 int fd, i;
307
308 assert(lttng_userspace_probe_location_get_type(probe_location) ==
309 LTTNG_USERSPACE_PROBE_LOCATION_TYPE_TRACEPOINT);
310
311 lookup = lttng_userspace_probe_location_get_lookup_method(probe_location);
312 if (!lookup) {
313 ret = -1;
314 goto end;
315 }
316
317 lookup_method_type =
318 lttng_userspace_probe_location_lookup_method_get_type(lookup);
319
320 assert(lookup_method_type ==
321 LTTNG_USERSPACE_PROBE_LOCATION_LOOKUP_METHOD_TYPE_TRACEPOINT_SDT);
322
323
324 probe_name = lttng_userspace_probe_location_tracepoint_get_probe_name(
325 probe_location);
326 if (!probe_name) {
327 ret = -1;
328 goto end;
329 }
330
331 provider_name = lttng_userspace_probe_location_tracepoint_get_provider_name(
332 probe_location);
333 if (!provider_name) {
334 ret = -1;
335 goto end;
336 }
337
338 fd = lttng_userspace_probe_location_tracepoint_get_binary_fd(probe_location);
339 if (fd < 0) {
340 ret = -1;
341 goto end;
342 }
343
344 ret = run_as_extract_sdt_probe_offsets(fd, provider_name, probe_name,
345 session->uid, session->gid, offsets, offsets_count);
346 if (ret < 0) {
347 DBG("userspace probe offset calculation failed for sdt "
348 "probe %s:%s", provider_name, probe_name);
349 goto end;
350 }
351
352 if (*offsets_count == 0) {
353 DBG("no userspace probe offset found");
354 goto end;
355 }
356
357 DBG("%u userspace probe SDT offsets found for %s:%s at:",
358 *offsets_count, provider_name, probe_name);
359 for (i = 0; i < *offsets_count; i++) {
360 DBG("\t0x%jd", (intmax_t)((*offsets)[i]));
361 }
362 end:
363 return ret;
364 }
365
366 /*
367 * Extract the offsets of the instrumentation point for the different lookup
368 * methods.
369 */
370 static
371 int userspace_probe_add_callsites(struct lttng_event *ev,
372 struct ltt_kernel_session *session, int fd)
373 {
374 const struct lttng_userspace_probe_location_lookup_method *lookup_method = NULL;
375 enum lttng_userspace_probe_location_lookup_method_type type;
376 const struct lttng_userspace_probe_location *location = NULL;
377 int ret;
378
379 assert(ev);
380 assert(ev->type == LTTNG_EVENT_USERSPACE_PROBE);
381
382 location = lttng_event_get_userspace_probe_location(ev);
383 if (!location) {
384 ret = -1;
385 goto end;
386 }
387 lookup_method =
388 lttng_userspace_probe_location_get_lookup_method(location);
389 if (!lookup_method) {
390 ret = -1;
391 goto end;
392 }
393
394 type = lttng_userspace_probe_location_lookup_method_get_type(lookup_method);
395 switch (type) {
396 case LTTNG_USERSPACE_PROBE_LOCATION_LOOKUP_METHOD_TYPE_FUNCTION_ELF:
397 {
398 struct lttng_kernel_event_callsite callsite;
399 uint64_t offset;
400
401 ret = extract_userspace_probe_offset_function_elf(location, session, &offset);
402 if (ret) {
403 ret = LTTNG_ERR_PROBE_LOCATION_INVAL;
404 goto end;
405 }
406
407 callsite.u.uprobe.offset = offset;
408 ret = kernctl_add_callsite(fd, &callsite);
409 if (ret) {
410 WARN("Adding callsite to userspace probe "
411 "event %s failed.", ev->name);
412 ret = LTTNG_ERR_KERN_ENABLE_FAIL;
413 goto end;
414 }
415 break;
416 }
417 case LTTNG_USERSPACE_PROBE_LOCATION_LOOKUP_METHOD_TYPE_TRACEPOINT_SDT:
418 {
419 int i;
420 uint64_t *offsets = NULL;
421 uint32_t offsets_count;
422 struct lttng_kernel_event_callsite callsite;
423
424 /*
425 * This call allocates the offsets buffer. This buffer must be freed
426 * by the caller
427 */
428 ret = extract_userspace_probe_offset_tracepoint_sdt(location, session,
429 &offsets, &offsets_count);
430 if (ret) {
431 ret = LTTNG_ERR_PROBE_LOCATION_INVAL;
432 goto end;
433 }
434 for (i = 0; i < offsets_count; i++) {
435 callsite.u.uprobe.offset = offsets[i];
436 ret = kernctl_add_callsite(fd, &callsite);
437 if (ret) {
438 WARN("Adding callsite to userspace probe "
439 "event %s failed.", ev->name);
440 ret = LTTNG_ERR_KERN_ENABLE_FAIL;
441 free(offsets);
442 goto end;
443 }
444 }
445 free(offsets);
446 break;
447 }
448 default:
449 ret = LTTNG_ERR_PROBE_LOCATION_INVAL;
450 goto end;
451 }
452 end:
453 return ret;
454 }
455
456 /*
457 * Create a kernel event, enable it to the kernel tracer and add it to the
458 * channel event list of the kernel session.
459 * We own filter_expression and filter.
460 */
461 int kernel_create_event(struct lttng_event *ev,
462 struct ltt_kernel_channel *channel,
463 char *filter_expression,
464 struct lttng_filter_bytecode *filter)
465 {
466 int err, fd;
467 enum lttng_error_code ret;
468 struct ltt_kernel_event *event;
469
470 assert(ev);
471 assert(channel);
472
473 /* We pass ownership of filter_expression and filter */
474 ret = trace_kernel_create_event(ev, filter_expression,
475 filter, &event);
476 if (ret != LTTNG_OK) {
477 goto error;
478 }
479
480 fd = kernctl_create_event(channel->fd, event->event);
481 if (fd < 0) {
482 switch (-fd) {
483 case EEXIST:
484 ret = LTTNG_ERR_KERN_EVENT_EXIST;
485 break;
486 case ENOSYS:
487 WARN("Event type not implemented");
488 ret = LTTNG_ERR_KERN_EVENT_ENOSYS;
489 break;
490 case ENOENT:
491 WARN("Event %s not found!", ev->name);
492 ret = LTTNG_ERR_KERN_ENABLE_FAIL;
493 break;
494 default:
495 ret = LTTNG_ERR_KERN_ENABLE_FAIL;
496 PERROR("create event ioctl");
497 }
498 goto free_event;
499 }
500
501 event->type = ev->type;
502 event->fd = fd;
503 /* Prevent fd duplication after execlp() */
504 err = fcntl(event->fd, F_SETFD, FD_CLOEXEC);
505 if (err < 0) {
506 PERROR("fcntl session fd");
507 }
508
509 if (filter) {
510 err = kernctl_filter(event->fd, filter);
511 if (err < 0) {
512 switch (-err) {
513 case ENOMEM:
514 ret = LTTNG_ERR_FILTER_NOMEM;
515 break;
516 default:
517 ret = LTTNG_ERR_FILTER_INVAL;
518 break;
519 }
520 goto filter_error;
521 }
522 }
523
524 if (ev->type == LTTNG_EVENT_USERSPACE_PROBE) {
525 ret = userspace_probe_add_callsites(ev, channel->session, event->fd);
526 if (ret) {
527 goto add_callsite_error;
528 }
529 }
530
531 err = kernctl_enable(event->fd);
532 if (err < 0) {
533 switch (-err) {
534 case EEXIST:
535 ret = LTTNG_ERR_KERN_EVENT_EXIST;
536 break;
537 default:
538 PERROR("enable kernel event");
539 ret = LTTNG_ERR_KERN_ENABLE_FAIL;
540 break;
541 }
542 goto enable_error;
543 }
544
545 /* Add event to event list */
546 cds_list_add(&event->list, &channel->events_list.head);
547 channel->event_count++;
548
549 DBG("Event %s created (fd: %d)", ev->name, event->fd);
550
551 return 0;
552
553 add_callsite_error:
554 enable_error:
555 filter_error:
556 {
557 int closeret;
558
559 closeret = close(event->fd);
560 if (closeret) {
561 PERROR("close event fd");
562 }
563 }
564 free_event:
565 free(event);
566 error:
567 return ret;
568 }
569
570 /*
571 * Disable a kernel channel.
572 */
573 int kernel_disable_channel(struct ltt_kernel_channel *chan)
574 {
575 int ret;
576
577 assert(chan);
578
579 ret = kernctl_disable(chan->fd);
580 if (ret < 0) {
581 PERROR("disable chan ioctl");
582 goto error;
583 }
584
585 chan->enabled = 0;
586 DBG("Kernel channel %s disabled (fd: %d, key: %" PRIu64 ")",
587 chan->channel->name, chan->fd, chan->key);
588
589 return 0;
590
591 error:
592 return ret;
593 }
594
595 /*
596 * Enable a kernel channel.
597 */
598 int kernel_enable_channel(struct ltt_kernel_channel *chan)
599 {
600 int ret;
601
602 assert(chan);
603
604 ret = kernctl_enable(chan->fd);
605 if (ret < 0 && ret != -EEXIST) {
606 PERROR("Enable kernel chan");
607 goto error;
608 }
609
610 chan->enabled = 1;
611 DBG("Kernel channel %s enabled (fd: %d, key: %" PRIu64 ")",
612 chan->channel->name, chan->fd, chan->key);
613
614 return 0;
615
616 error:
617 return ret;
618 }
619
620 /*
621 * Enable a kernel event.
622 */
623 int kernel_enable_event(struct ltt_kernel_event *event)
624 {
625 int ret;
626
627 assert(event);
628
629 ret = kernctl_enable(event->fd);
630 if (ret < 0) {
631 switch (-ret) {
632 case EEXIST:
633 ret = LTTNG_ERR_KERN_EVENT_EXIST;
634 break;
635 default:
636 PERROR("enable kernel event");
637 break;
638 }
639 goto error;
640 }
641
642 event->enabled = 1;
643 DBG("Kernel event %s enabled (fd: %d)", event->event->name, event->fd);
644
645 return 0;
646
647 error:
648 return ret;
649 }
650
651 /*
652 * Disable a kernel event.
653 */
654 int kernel_disable_event(struct ltt_kernel_event *event)
655 {
656 int ret;
657
658 assert(event);
659
660 ret = kernctl_disable(event->fd);
661 if (ret < 0) {
662 switch (-ret) {
663 case EEXIST:
664 ret = LTTNG_ERR_KERN_EVENT_EXIST;
665 break;
666 default:
667 PERROR("disable kernel event");
668 break;
669 }
670 goto error;
671 }
672
673 event->enabled = 0;
674 DBG("Kernel event %s disabled (fd: %d)", event->event->name, event->fd);
675
676 return 0;
677
678 error:
679 return ret;
680 }
681
682
683 int kernel_track_pid(struct ltt_kernel_session *session, int pid)
684 {
685 int ret;
686
687 DBG("Kernel track PID %d for session id %" PRIu64 ".",
688 pid, session->id);
689 ret = kernctl_track_pid(session->fd, pid);
690 if (!ret) {
691 return LTTNG_OK;
692 }
693 switch (-ret) {
694 case EINVAL:
695 return LTTNG_ERR_INVALID;
696 case ENOMEM:
697 return LTTNG_ERR_NOMEM;
698 case EEXIST:
699 return LTTNG_ERR_PID_TRACKED;
700 default:
701 return LTTNG_ERR_UNK;
702 }
703 }
704
705 int kernel_untrack_pid(struct ltt_kernel_session *session, int pid)
706 {
707 int ret;
708
709 DBG("Kernel untrack PID %d for session id %" PRIu64 ".",
710 pid, session->id);
711 ret = kernctl_untrack_pid(session->fd, pid);
712 if (!ret) {
713 return LTTNG_OK;
714 }
715 switch (-ret) {
716 case EINVAL:
717 return LTTNG_ERR_INVALID;
718 case ENOMEM:
719 return LTTNG_ERR_NOMEM;
720 case ENOENT:
721 return LTTNG_ERR_PID_NOT_TRACKED;
722 default:
723 return LTTNG_ERR_UNK;
724 }
725 }
726
727 ssize_t kernel_list_tracker_pids(struct ltt_kernel_session *session,
728 int **_pids)
729 {
730 int fd, ret;
731 int pid;
732 ssize_t nbmem, count = 0;
733 FILE *fp;
734 int *pids;
735
736 fd = kernctl_list_tracker_pids(session->fd);
737 if (fd < 0) {
738 PERROR("kernel tracker pids list");
739 goto error;
740 }
741
742 fp = fdopen(fd, "r");
743 if (fp == NULL) {
744 PERROR("kernel tracker pids list fdopen");
745 goto error_fp;
746 }
747
748 nbmem = KERNEL_TRACKER_PIDS_INIT_LIST_SIZE;
749 pids = zmalloc(sizeof(*pids) * nbmem);
750 if (pids == NULL) {
751 PERROR("alloc list pids");
752 count = -ENOMEM;
753 goto end;
754 }
755
756 while (fscanf(fp, "process { pid = %u; };\n", &pid) == 1) {
757 if (count >= nbmem) {
758 int *new_pids;
759 size_t new_nbmem;
760
761 new_nbmem = nbmem << 1;
762 DBG("Reallocating pids list from %zu to %zu entries",
763 nbmem, new_nbmem);
764 new_pids = realloc(pids, new_nbmem * sizeof(*new_pids));
765 if (new_pids == NULL) {
766 PERROR("realloc list events");
767 free(pids);
768 count = -ENOMEM;
769 goto end;
770 }
771 /* Zero the new memory */
772 memset(new_pids + nbmem, 0,
773 (new_nbmem - nbmem) * sizeof(*new_pids));
774 nbmem = new_nbmem;
775 pids = new_pids;
776 }
777 pids[count++] = pid;
778 }
779
780 *_pids = pids;
781 DBG("Kernel list tracker pids done (%zd pids)", count);
782 end:
783 ret = fclose(fp); /* closes both fp and fd */
784 if (ret) {
785 PERROR("fclose");
786 }
787 return count;
788
789 error_fp:
790 ret = close(fd);
791 if (ret) {
792 PERROR("close");
793 }
794 error:
795 return -1;
796 }
797
798 /*
799 * Create kernel metadata, open from the kernel tracer and add it to the
800 * kernel session.
801 */
802 int kernel_open_metadata(struct ltt_kernel_session *session)
803 {
804 int ret;
805 struct ltt_kernel_metadata *lkm = NULL;
806
807 assert(session);
808
809 /* Allocate kernel metadata */
810 lkm = trace_kernel_create_metadata();
811 if (lkm == NULL) {
812 goto error;
813 }
814
815 /* Kernel tracer metadata creation */
816 ret = kernctl_open_metadata(session->fd, &lkm->conf->attr);
817 if (ret < 0) {
818 goto error_open;
819 }
820
821 lkm->fd = ret;
822 lkm->key = ++next_kernel_channel_key;
823 /* Prevent fd duplication after execlp() */
824 ret = fcntl(lkm->fd, F_SETFD, FD_CLOEXEC);
825 if (ret < 0) {
826 PERROR("fcntl session fd");
827 }
828
829 session->metadata = lkm;
830
831 DBG("Kernel metadata opened (fd: %d)", lkm->fd);
832
833 return 0;
834
835 error_open:
836 trace_kernel_destroy_metadata(lkm);
837 error:
838 return -1;
839 }
840
841 /*
842 * Start tracing session.
843 */
844 int kernel_start_session(struct ltt_kernel_session *session)
845 {
846 int ret;
847
848 assert(session);
849
850 ret = kernctl_start_session(session->fd);
851 if (ret < 0) {
852 PERROR("ioctl start session");
853 goto error;
854 }
855
856 DBG("Kernel session started");
857
858 return 0;
859
860 error:
861 return ret;
862 }
863
864 /*
865 * Make a kernel wait to make sure in-flight probe have completed.
866 */
867 void kernel_wait_quiescent(void)
868 {
869 int ret;
870 int fd = kernel_tracer_fd;
871
872 DBG("Kernel quiescent wait on %d", fd);
873
874 ret = kernctl_wait_quiescent(fd);
875 if (ret < 0) {
876 PERROR("wait quiescent ioctl");
877 ERR("Kernel quiescent wait failed");
878 }
879 }
880
881 /*
882 * Force flush buffer of metadata.
883 */
884 int kernel_metadata_flush_buffer(int fd)
885 {
886 int ret;
887
888 DBG("Kernel flushing metadata buffer on fd %d", fd);
889
890 ret = kernctl_buffer_flush(fd);
891 if (ret < 0) {
892 ERR("Fail to flush metadata buffers %d (ret: %d)", fd, ret);
893 }
894
895 return 0;
896 }
897
898 /*
899 * Force flush buffer for channel.
900 */
901 int kernel_flush_buffer(struct ltt_kernel_channel *channel)
902 {
903 int ret;
904 struct ltt_kernel_stream *stream;
905
906 assert(channel);
907
908 DBG("Flush buffer for channel %s", channel->channel->name);
909
910 cds_list_for_each_entry(stream, &channel->stream_list.head, list) {
911 DBG("Flushing channel stream %d", stream->fd);
912 ret = kernctl_buffer_flush(stream->fd);
913 if (ret < 0) {
914 PERROR("ioctl");
915 ERR("Fail to flush buffer for stream %d (ret: %d)",
916 stream->fd, ret);
917 }
918 }
919
920 return 0;
921 }
922
923 /*
924 * Stop tracing session.
925 */
926 int kernel_stop_session(struct ltt_kernel_session *session)
927 {
928 int ret;
929
930 assert(session);
931
932 ret = kernctl_stop_session(session->fd);
933 if (ret < 0) {
934 goto error;
935 }
936
937 DBG("Kernel session stopped");
938
939 return 0;
940
941 error:
942 return ret;
943 }
944
945 /*
946 * Open stream of channel, register it to the kernel tracer and add it
947 * to the stream list of the channel.
948 *
949 * Note: given that the streams may appear in random order wrt CPU
950 * number (e.g. cpu hotplug), the index value of the stream number in
951 * the stream name is not necessarily linked to the CPU number.
952 *
953 * Return the number of created stream. Else, a negative value.
954 */
955 int kernel_open_channel_stream(struct ltt_kernel_channel *channel)
956 {
957 int ret;
958 struct ltt_kernel_stream *lks;
959
960 assert(channel);
961
962 while ((ret = kernctl_create_stream(channel->fd)) >= 0) {
963 lks = trace_kernel_create_stream(channel->channel->name,
964 channel->stream_count);
965 if (lks == NULL) {
966 ret = close(ret);
967 if (ret) {
968 PERROR("close");
969 }
970 goto error;
971 }
972
973 lks->fd = ret;
974 /* Prevent fd duplication after execlp() */
975 ret = fcntl(lks->fd, F_SETFD, FD_CLOEXEC);
976 if (ret < 0) {
977 PERROR("fcntl session fd");
978 }
979
980 lks->tracefile_size = channel->channel->attr.tracefile_size;
981 lks->tracefile_count = channel->channel->attr.tracefile_count;
982
983 /* Add stream to channel stream list */
984 cds_list_add(&lks->list, &channel->stream_list.head);
985 channel->stream_count++;
986
987 DBG("Kernel stream %s created (fd: %d, state: %d)", lks->name, lks->fd,
988 lks->state);
989 }
990
991 return channel->stream_count;
992
993 error:
994 return -1;
995 }
996
997 /*
998 * Open the metadata stream and set it to the kernel session.
999 */
1000 int kernel_open_metadata_stream(struct ltt_kernel_session *session)
1001 {
1002 int ret;
1003
1004 assert(session);
1005
1006 ret = kernctl_create_stream(session->metadata->fd);
1007 if (ret < 0) {
1008 PERROR("kernel create metadata stream");
1009 goto error;
1010 }
1011
1012 DBG("Kernel metadata stream created (fd: %d)", ret);
1013 session->metadata_stream_fd = ret;
1014 /* Prevent fd duplication after execlp() */
1015 ret = fcntl(session->metadata_stream_fd, F_SETFD, FD_CLOEXEC);
1016 if (ret < 0) {
1017 PERROR("fcntl session fd");
1018 }
1019
1020 return 0;
1021
1022 error:
1023 return -1;
1024 }
1025
1026 /*
1027 * Get the event list from the kernel tracer and return the number of elements.
1028 */
1029 ssize_t kernel_list_events(struct lttng_event **events)
1030 {
1031 int fd, ret;
1032 char *event;
1033 size_t nbmem, count = 0;
1034 FILE *fp;
1035 struct lttng_event *elist;
1036
1037 assert(events);
1038
1039 fd = kernctl_tracepoint_list(kernel_tracer_fd);
1040 if (fd < 0) {
1041 PERROR("kernel tracepoint list");
1042 goto error;
1043 }
1044
1045 fp = fdopen(fd, "r");
1046 if (fp == NULL) {
1047 PERROR("kernel tracepoint list fdopen");
1048 goto error_fp;
1049 }
1050
1051 /*
1052 * Init memory size counter
1053 * See kernel-ctl.h for explanation of this value
1054 */
1055 nbmem = KERNEL_EVENT_INIT_LIST_SIZE;
1056 elist = zmalloc(sizeof(struct lttng_event) * nbmem);
1057 if (elist == NULL) {
1058 PERROR("alloc list events");
1059 count = -ENOMEM;
1060 goto end;
1061 }
1062
1063 while (fscanf(fp, "event { name = %m[^;]; };\n", &event) == 1) {
1064 if (count >= nbmem) {
1065 struct lttng_event *new_elist;
1066 size_t new_nbmem;
1067
1068 new_nbmem = nbmem << 1;
1069 DBG("Reallocating event list from %zu to %zu bytes",
1070 nbmem, new_nbmem);
1071 new_elist = realloc(elist, new_nbmem * sizeof(struct lttng_event));
1072 if (new_elist == NULL) {
1073 PERROR("realloc list events");
1074 free(event);
1075 free(elist);
1076 count = -ENOMEM;
1077 goto end;
1078 }
1079 /* Zero the new memory */
1080 memset(new_elist + nbmem, 0,
1081 (new_nbmem - nbmem) * sizeof(struct lttng_event));
1082 nbmem = new_nbmem;
1083 elist = new_elist;
1084 }
1085 strncpy(elist[count].name, event, LTTNG_SYMBOL_NAME_LEN);
1086 elist[count].name[LTTNG_SYMBOL_NAME_LEN - 1] = '\0';
1087 elist[count].enabled = -1;
1088 count++;
1089 free(event);
1090 }
1091
1092 *events = elist;
1093 DBG("Kernel list events done (%zu events)", count);
1094 end:
1095 ret = fclose(fp); /* closes both fp and fd */
1096 if (ret) {
1097 PERROR("fclose");
1098 }
1099 return count;
1100
1101 error_fp:
1102 ret = close(fd);
1103 if (ret) {
1104 PERROR("close");
1105 }
1106 error:
1107 return -1;
1108 }
1109
1110 /*
1111 * Get kernel version and validate it.
1112 */
1113 int kernel_validate_version(struct lttng_kernel_tracer_version *version,
1114 struct lttng_kernel_tracer_abi_version *abi_version)
1115 {
1116 int ret;
1117
1118 ret = kernctl_tracer_version(kernel_tracer_fd, version);
1119 if (ret < 0) {
1120 ERR("Failed to retrieve the lttng-modules version");
1121 goto error;
1122 }
1123
1124 /* Validate version */
1125 if (version->major != VERSION_MAJOR) {
1126 ERR("Kernel tracer major version (%d) is not compatible with lttng-tools major version (%d)",
1127 version->major, VERSION_MAJOR);
1128 goto error_version;
1129 }
1130 ret = kernctl_tracer_abi_version(kernel_tracer_fd, abi_version);
1131 if (ret < 0) {
1132 ERR("Failed to retrieve lttng-modules ABI version");
1133 goto error;
1134 }
1135 if (abi_version->major != LTTNG_MODULES_ABI_MAJOR_VERSION) {
1136 ERR("Kernel tracer ABI version (%d.%d) does not match the expected ABI major version (%d.*)",
1137 abi_version->major, abi_version->minor,
1138 LTTNG_MODULES_ABI_MAJOR_VERSION);
1139 goto error;
1140 }
1141 DBG2("Kernel tracer version validated (%d.%d, ABI %d.%d)",
1142 version->major, version->minor,
1143 abi_version->major, abi_version->minor);
1144 return 0;
1145
1146 error_version:
1147 ret = -1;
1148
1149 error:
1150 ERR("Kernel tracer version check failed; kernel tracing will not be available");
1151 return ret;
1152 }
1153
1154 /*
1155 * Kernel work-arounds called at the start of sessiond main().
1156 */
1157 int init_kernel_workarounds(void)
1158 {
1159 int ret;
1160 FILE *fp;
1161
1162 /*
1163 * boot_id needs to be read once before being used concurrently
1164 * to deal with a Linux kernel race. A fix is proposed for
1165 * upstream, but the work-around is needed for older kernels.
1166 */
1167 fp = fopen("/proc/sys/kernel/random/boot_id", "r");
1168 if (!fp) {
1169 goto end_boot_id;
1170 }
1171 while (!feof(fp)) {
1172 char buf[37] = "";
1173
1174 ret = fread(buf, 1, sizeof(buf), fp);
1175 if (ret < 0) {
1176 /* Ignore error, we don't really care */
1177 }
1178 }
1179 ret = fclose(fp);
1180 if (ret) {
1181 PERROR("fclose");
1182 }
1183 end_boot_id:
1184 return 0;
1185 }
1186
1187 /*
1188 * Teardown of a kernel session, keeping data required by destroy notifiers.
1189 */
1190 void kernel_destroy_session(struct ltt_kernel_session *ksess)
1191 {
1192 struct lttng_trace_chunk *trace_chunk;
1193
1194 if (ksess == NULL) {
1195 DBG3("No kernel session when tearing down session");
1196 return;
1197 }
1198
1199 DBG("Tearing down kernel session");
1200 trace_chunk = ksess->current_trace_chunk;
1201
1202 /*
1203 * Destroy channels on the consumer if at least one FD has been sent and we
1204 * are in no output mode because the streams are in *no* monitor mode so we
1205 * have to send a command to clean them up or else they leaked.
1206 */
1207 if (!ksess->output_traces && ksess->consumer_fds_sent) {
1208 int ret;
1209 struct consumer_socket *socket;
1210 struct lttng_ht_iter iter;
1211
1212 /* For each consumer socket. */
1213 rcu_read_lock();
1214 cds_lfht_for_each_entry(ksess->consumer->socks->ht, &iter.iter,
1215 socket, node.node) {
1216 struct ltt_kernel_channel *chan;
1217
1218 /* For each channel, ask the consumer to destroy it. */
1219 cds_list_for_each_entry(chan, &ksess->channel_list.head, list) {
1220 ret = kernel_consumer_destroy_channel(socket, chan);
1221 if (ret < 0) {
1222 /* Consumer is probably dead. Use next socket. */
1223 continue;
1224 }
1225 }
1226 }
1227 rcu_read_unlock();
1228 }
1229
1230 /* Close any relayd session */
1231 consumer_output_send_destroy_relayd(ksess->consumer);
1232
1233 trace_kernel_destroy_session(ksess);
1234 lttng_trace_chunk_put(trace_chunk);
1235 }
1236
1237 /* Teardown of data required by destroy notifiers. */
1238 void kernel_free_session(struct ltt_kernel_session *ksess)
1239 {
1240 if (ksess == NULL) {
1241 return;
1242 }
1243 trace_kernel_free_session(ksess);
1244 }
1245
1246 /*
1247 * Destroy a kernel channel object. It does not do anything on the tracer side.
1248 */
1249 void kernel_destroy_channel(struct ltt_kernel_channel *kchan)
1250 {
1251 struct ltt_kernel_session *ksess = NULL;
1252
1253 assert(kchan);
1254 assert(kchan->channel);
1255
1256 DBG3("Kernel destroy channel %s", kchan->channel->name);
1257
1258 /* Update channel count of associated session. */
1259 if (kchan->session) {
1260 /* Keep pointer reference so we can update it after the destroy. */
1261 ksess = kchan->session;
1262 }
1263
1264 trace_kernel_destroy_channel(kchan);
1265
1266 /*
1267 * At this point the kernel channel is not visible anymore. This is safe
1268 * since in order to work on a visible kernel session, the tracing session
1269 * lock (ltt_session.lock) MUST be acquired.
1270 */
1271 if (ksess) {
1272 ksess->channel_count--;
1273 }
1274 }
1275
1276 /*
1277 * Take a snapshot for a given kernel session.
1278 *
1279 * Return LTTNG_OK on success or else return a LTTNG_ERR code.
1280 */
1281 enum lttng_error_code kernel_snapshot_record(
1282 struct ltt_kernel_session *ksess,
1283 const struct consumer_output *output, int wait,
1284 uint64_t nb_packets_per_stream)
1285 {
1286 int err, ret, saved_metadata_fd;
1287 enum lttng_error_code status = LTTNG_OK;
1288 struct consumer_socket *socket;
1289 struct lttng_ht_iter iter;
1290 struct ltt_kernel_metadata *saved_metadata;
1291 char *trace_path = NULL;
1292 size_t consumer_path_offset = 0;
1293
1294 assert(ksess);
1295 assert(ksess->consumer);
1296 assert(output);
1297
1298 DBG("Kernel snapshot record started");
1299
1300 /* Save current metadata since the following calls will change it. */
1301 saved_metadata = ksess->metadata;
1302 saved_metadata_fd = ksess->metadata_stream_fd;
1303
1304 rcu_read_lock();
1305
1306 ret = kernel_open_metadata(ksess);
1307 if (ret < 0) {
1308 status = LTTNG_ERR_KERN_META_FAIL;
1309 goto error;
1310 }
1311
1312 ret = kernel_open_metadata_stream(ksess);
1313 if (ret < 0) {
1314 status = LTTNG_ERR_KERN_META_FAIL;
1315 goto error_open_stream;
1316 }
1317
1318 trace_path = setup_channel_trace_path(ksess->consumer,
1319 DEFAULT_KERNEL_TRACE_DIR, &consumer_path_offset);
1320 if (!trace_path) {
1321 status = LTTNG_ERR_INVALID;
1322 goto error;
1323 }
1324 /* Send metadata to consumer and snapshot everything. */
1325 cds_lfht_for_each_entry(output->socks->ht, &iter.iter,
1326 socket, node.node) {
1327 struct ltt_kernel_channel *chan;
1328
1329 pthread_mutex_lock(socket->lock);
1330 /* This stream must not be monitored by the consumer. */
1331 ret = kernel_consumer_add_metadata(socket, ksess, 0);
1332 pthread_mutex_unlock(socket->lock);
1333 if (ret < 0) {
1334 status = LTTNG_ERR_KERN_META_FAIL;
1335 goto error_consumer;
1336 }
1337
1338 /* For each channel, ask the consumer to snapshot it. */
1339 cds_list_for_each_entry(chan, &ksess->channel_list.head, list) {
1340 status = consumer_snapshot_channel(socket, chan->key, output, 0,
1341 ksess->uid, ksess->gid,
1342 &trace_path[consumer_path_offset], wait,
1343 nb_packets_per_stream);
1344 if (status != LTTNG_OK) {
1345 (void) kernel_consumer_destroy_metadata(socket,
1346 ksess->metadata);
1347 goto error_consumer;
1348 }
1349 }
1350
1351 /* Snapshot metadata, */
1352 status = consumer_snapshot_channel(socket, ksess->metadata->key, output,
1353 1, ksess->uid, ksess->gid, &trace_path[consumer_path_offset],
1354 wait, 0);
1355 if (status != LTTNG_OK) {
1356 goto error_consumer;
1357 }
1358
1359 /*
1360 * The metadata snapshot is done, ask the consumer to destroy it since
1361 * it's not monitored on the consumer side.
1362 */
1363 (void) kernel_consumer_destroy_metadata(socket, ksess->metadata);
1364 }
1365
1366 error_consumer:
1367 /* Close newly opened metadata stream. It's now on the consumer side. */
1368 err = close(ksess->metadata_stream_fd);
1369 if (err < 0) {
1370 PERROR("close snapshot kernel");
1371 }
1372
1373 error_open_stream:
1374 trace_kernel_destroy_metadata(ksess->metadata);
1375 error:
1376 /* Restore metadata state.*/
1377 ksess->metadata = saved_metadata;
1378 ksess->metadata_stream_fd = saved_metadata_fd;
1379 rcu_read_unlock();
1380 free(trace_path);
1381 return status;
1382 }
1383
1384 /*
1385 * Get the syscall mask array from the kernel tracer.
1386 *
1387 * Return 0 on success else a negative value. In both case, syscall_mask should
1388 * be freed.
1389 */
1390 int kernel_syscall_mask(int chan_fd, char **syscall_mask, uint32_t *nr_bits)
1391 {
1392 assert(syscall_mask);
1393 assert(nr_bits);
1394
1395 return kernctl_syscall_mask(chan_fd, syscall_mask, nr_bits);
1396 }
1397
1398 /*
1399 * Check for the support of the RING_BUFFER_SNAPSHOT_SAMPLE_POSITIONS via abi
1400 * version number.
1401 *
1402 * Return 1 on success, 0 when feature is not supported, negative value in case
1403 * of errors.
1404 */
1405 int kernel_supports_ring_buffer_snapshot_sample_positions(void)
1406 {
1407 int ret = 0; // Not supported by default
1408 struct lttng_kernel_tracer_abi_version abi;
1409
1410 ret = kernctl_tracer_abi_version(kernel_tracer_fd, &abi);
1411 if (ret < 0) {
1412 ERR("Failed to retrieve lttng-modules ABI version");
1413 goto error;
1414 }
1415
1416 /*
1417 * RING_BUFFER_SNAPSHOT_SAMPLE_POSITIONS was introduced in 2.3
1418 */
1419 if (abi.major >= 2 && abi.minor >= 3) {
1420 /* Supported */
1421 ret = 1;
1422 } else {
1423 /* Not supported */
1424 ret = 0;
1425 }
1426 error:
1427 return ret;
1428 }
1429
1430 /*
1431 * Check for the support of the packet sequence number via abi version number.
1432 *
1433 * Return 1 on success, 0 when feature is not supported, negative value in case
1434 * of errors.
1435 */
1436 int kernel_supports_ring_buffer_packet_sequence_number(void)
1437 {
1438 int ret = 0; // Not supported by default
1439 struct lttng_kernel_tracer_abi_version abi;
1440
1441 ret = kernctl_tracer_abi_version(kernel_tracer_fd, &abi);
1442 if (ret < 0) {
1443 ERR("Failed to retrieve lttng-modules ABI version");
1444 goto error;
1445 }
1446
1447 /*
1448 * Packet sequence number was introduced in LTTng 2.8,
1449 * lttng-modules ABI 2.1.
1450 */
1451 if (abi.major >= 2 && abi.minor >= 1) {
1452 /* Supported */
1453 ret = 1;
1454 } else {
1455 /* Not supported */
1456 ret = 0;
1457 }
1458 error:
1459 return ret;
1460 }
1461
1462 /*
1463 * Rotate a kernel session.
1464 *
1465 * Return LTTNG_OK on success or else an LTTng error code.
1466 */
1467 enum lttng_error_code kernel_rotate_session(struct ltt_session *session)
1468 {
1469 int ret;
1470 enum lttng_error_code status = LTTNG_OK;
1471 struct consumer_socket *socket;
1472 struct lttng_ht_iter iter;
1473 struct ltt_kernel_session *ksess = session->kernel_session;
1474
1475 assert(ksess);
1476 assert(ksess->consumer);
1477
1478 DBG("Rotate kernel session %s started (session %" PRIu64 ")",
1479 session->name, session->id);
1480
1481 rcu_read_lock();
1482
1483 /*
1484 * Note that this loop will end after one iteration given that there is
1485 * only one kernel consumer.
1486 */
1487 cds_lfht_for_each_entry(ksess->consumer->socks->ht, &iter.iter,
1488 socket, node.node) {
1489 struct ltt_kernel_channel *chan;
1490
1491 /* For each channel, ask the consumer to rotate it. */
1492 cds_list_for_each_entry(chan, &ksess->channel_list.head, list) {
1493 DBG("Rotate kernel channel %" PRIu64 ", session %s",
1494 chan->key, session->name);
1495 ret = consumer_rotate_channel(socket, chan->key,
1496 ksess->uid, ksess->gid, ksess->consumer,
1497 /* is_metadata_channel */ false);
1498 if (ret < 0) {
1499 status = LTTNG_ERR_KERN_CONSUMER_FAIL;
1500 goto error;
1501 }
1502 }
1503
1504 /*
1505 * Rotate the metadata channel.
1506 */
1507 ret = consumer_rotate_channel(socket, ksess->metadata->key,
1508 ksess->uid, ksess->gid, ksess->consumer,
1509 /* is_metadata_channel */ true);
1510 if (ret < 0) {
1511 status = LTTNG_ERR_KERN_CONSUMER_FAIL;
1512 goto error;
1513 }
1514 }
1515
1516 error:
1517 rcu_read_unlock();
1518 return status;
1519 }
1520
1521 enum lttng_error_code kernel_create_channel_subdirectories(
1522 const struct ltt_kernel_session *ksess)
1523 {
1524 enum lttng_error_code ret = LTTNG_OK;
1525 enum lttng_trace_chunk_status chunk_status;
1526
1527 rcu_read_lock();
1528 assert(ksess->current_trace_chunk);
1529
1530 /*
1531 * Create the index subdirectory which will take care
1532 * of implicitly creating the channel's path.
1533 */
1534 chunk_status = lttng_trace_chunk_create_subdirectory(
1535 ksess->current_trace_chunk,
1536 DEFAULT_KERNEL_TRACE_DIR "/" DEFAULT_INDEX_DIR);
1537 if (chunk_status != LTTNG_TRACE_CHUNK_STATUS_OK) {
1538 ret = LTTNG_ERR_CREATE_DIR_FAIL;
1539 goto error;
1540 }
1541 error:
1542 rcu_read_unlock();
1543 return ret;
1544 }
1545
1546 /*
1547 * Setup necessary data for kernel tracer action.
1548 */
1549 LTTNG_HIDDEN
1550 int init_kernel_tracer(void)
1551 {
1552 int ret;
1553 bool is_root = !getuid();
1554
1555 /* Modprobe lttng kernel modules */
1556 ret = modprobe_lttng_control();
1557 if (ret < 0) {
1558 goto error;
1559 }
1560
1561 /* Open debugfs lttng */
1562 kernel_tracer_fd = open(module_proc_lttng, O_RDWR);
1563 if (kernel_tracer_fd < 0) {
1564 DBG("Failed to open %s", module_proc_lttng);
1565 goto error_open;
1566 }
1567
1568 /* Validate kernel version */
1569 ret = kernel_validate_version(&kernel_tracer_version,
1570 &kernel_tracer_abi_version);
1571 if (ret < 0) {
1572 goto error_version;
1573 }
1574
1575 ret = modprobe_lttng_data();
1576 if (ret < 0) {
1577 goto error_modules;
1578 }
1579
1580 ret = kernel_supports_ring_buffer_snapshot_sample_positions();
1581 if (ret < 0) {
1582 goto error_modules;
1583 }
1584
1585 if (ret < 1) {
1586 WARN("Kernel tracer does not support buffer monitoring. "
1587 "The monitoring timer of channels in the kernel domain "
1588 "will be set to 0 (disabled).");
1589 }
1590
1591 DBG("Kernel tracer fd %d", kernel_tracer_fd);
1592
1593 ret = syscall_init_table(kernel_tracer_fd);
1594 if (ret < 0) {
1595 ERR("Unable to populate syscall table. Syscall tracing won't "
1596 "work for this session daemon.");
1597 }
1598 return 0;
1599
1600 error_version:
1601 modprobe_remove_lttng_control();
1602 ret = close(kernel_tracer_fd);
1603 if (ret) {
1604 PERROR("close");
1605 }
1606 kernel_tracer_fd = -1;
1607 return LTTNG_ERR_KERN_VERSION;
1608
1609 error_modules:
1610 ret = close(kernel_tracer_fd);
1611 if (ret) {
1612 PERROR("close");
1613 }
1614
1615 error_open:
1616 modprobe_remove_lttng_control();
1617
1618 error:
1619 WARN("No kernel tracer available");
1620 kernel_tracer_fd = -1;
1621 if (!is_root) {
1622 return LTTNG_ERR_NEED_ROOT_SESSIOND;
1623 } else {
1624 return LTTNG_ERR_KERN_NA;
1625 }
1626 }
1627
1628 LTTNG_HIDDEN
1629 void cleanup_kernel_tracer(void)
1630 {
1631 int ret;
1632
1633 DBG2("Closing kernel fd");
1634 if (kernel_tracer_fd >= 0) {
1635 ret = close(kernel_tracer_fd);
1636 if (ret) {
1637 PERROR("close");
1638 }
1639 kernel_tracer_fd = -1;
1640 }
1641 DBG("Unloading kernel modules");
1642 modprobe_remove_lttng_all();
1643 free(syscall_table);
1644 }
1645
1646 LTTNG_HIDDEN
1647 bool kernel_tracer_is_initialized(void)
1648 {
1649 return kernel_tracer_fd >= 0;
1650 }
1651
1652 /*
1653 * Clear a kernel session.
1654 *
1655 * Return LTTNG_OK on success or else an LTTng error code.
1656 */
1657 enum lttng_error_code kernel_clear_session(struct ltt_session *session)
1658 {
1659 int ret;
1660 enum lttng_error_code status = LTTNG_OK;
1661 struct consumer_socket *socket;
1662 struct lttng_ht_iter iter;
1663 struct ltt_kernel_session *ksess = session->kernel_session;
1664
1665 assert(ksess);
1666 assert(ksess->consumer);
1667
1668 DBG("Clear kernel session %s (session %" PRIu64 ")",
1669 session->name, session->id);
1670
1671 rcu_read_lock();
1672
1673 if (ksess->active) {
1674 ERR("Expecting inactive session %s (%" PRIu64 ")", session->name, session->id);
1675 status = LTTNG_ERR_FATAL;
1676 goto end;
1677 }
1678
1679 /*
1680 * Note that this loop will end after one iteration given that there is
1681 * only one kernel consumer.
1682 */
1683 cds_lfht_for_each_entry(ksess->consumer->socks->ht, &iter.iter,
1684 socket, node.node) {
1685 struct ltt_kernel_channel *chan;
1686
1687 /* For each channel, ask the consumer to clear it. */
1688 cds_list_for_each_entry(chan, &ksess->channel_list.head, list) {
1689 DBG("Clear kernel channel %" PRIu64 ", session %s",
1690 chan->key, session->name);
1691 ret = consumer_clear_channel(socket, chan->key);
1692 if (ret < 0) {
1693 goto error;
1694 }
1695 }
1696
1697 if (!ksess->metadata) {
1698 /*
1699 * Nothing to do for the metadata.
1700 * This is a snapshot session.
1701 * The metadata is genererated on the fly.
1702 */
1703 continue;
1704 }
1705
1706 /*
1707 * Clear the metadata channel.
1708 * Metadata channel is not cleared per se but we still need to
1709 * perform a rotation operation on it behind the scene.
1710 */
1711 ret = consumer_clear_channel(socket, ksess->metadata->key);
1712 if (ret < 0) {
1713 goto error;
1714 }
1715 }
1716
1717 goto end;
1718 error:
1719 switch (-ret) {
1720 case LTTCOMM_CONSUMERD_RELAYD_CLEAR_DISALLOWED:
1721 status = LTTNG_ERR_CLEAR_RELAY_DISALLOWED;
1722 break;
1723 default:
1724 status = LTTNG_ERR_CLEAR_FAIL_CONSUMER;
1725 break;
1726 }
1727 end:
1728 rcu_read_unlock();
1729 return status;
1730 }
This page took 0.110421 seconds and 4 git commands to generate.