Wait for the destruction of sessions before tearing down main thread
[lttng-tools.git] / src / bin / lttng-sessiond / session.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 <limits.h>
20 #include <inttypes.h>
21 #include <stdio.h>
22 #include <stdlib.h>
23 #include <string.h>
24 #include <sys/stat.h>
25 #include <urcu.h>
26 #include <dirent.h>
27 #include <sys/types.h>
28 #include <pthread.h>
29
30 #include <common/common.h>
31 #include <common/sessiond-comm/sessiond-comm.h>
32 #include <lttng/location-internal.h>
33 #include "lttng-sessiond.h"
34 #include "kernel.h"
35
36 #include "session.h"
37 #include "utils.h"
38 #include "trace-ust.h"
39 #include "timer.h"
40
41 /*
42 * NOTES:
43 *
44 * No ltt_session.lock is taken here because those data structure are widely
45 * spread across the lttng-tools code base so before caling functions below
46 * that can read/write a session, the caller MUST acquire the session lock
47 * using session_lock() and session_unlock().
48 */
49
50 /*
51 * Init tracing session list.
52 *
53 * Please see session.h for more explanation and correct usage of the list.
54 */
55 static struct ltt_session_list ltt_session_list = {
56 .head = CDS_LIST_HEAD_INIT(ltt_session_list.head),
57 .lock = PTHREAD_MUTEX_INITIALIZER,
58 .removal_cond = PTHREAD_COND_INITIALIZER,
59 .next_uuid = 0,
60 };
61
62 /* These characters are forbidden in a session name. Used by validate_name. */
63 static const char *forbidden_name_chars = "/";
64
65 /* Global hash table to keep the sessions, indexed by id. */
66 static struct lttng_ht *ltt_sessions_ht_by_id = NULL;
67
68 /*
69 * Validate the session name for forbidden characters.
70 *
71 * Return 0 on success else -1 meaning a forbidden char. has been found.
72 */
73 static int validate_name(const char *name)
74 {
75 int ret;
76 char *tok, *tmp_name;
77
78 assert(name);
79
80 tmp_name = strdup(name);
81 if (!tmp_name) {
82 /* ENOMEM here. */
83 ret = -1;
84 goto error;
85 }
86
87 tok = strpbrk(tmp_name, forbidden_name_chars);
88 if (tok) {
89 DBG("Session name %s contains a forbidden character", name);
90 /* Forbidden character has been found. */
91 ret = -1;
92 goto error;
93 }
94 ret = 0;
95
96 error:
97 free(tmp_name);
98 return ret;
99 }
100
101 /*
102 * Add a ltt_session structure to the global list.
103 *
104 * The caller MUST acquire the session list lock before.
105 * Returns the unique identifier for the session.
106 */
107 static uint64_t add_session_list(struct ltt_session *ls)
108 {
109 assert(ls);
110
111 cds_list_add(&ls->list, &ltt_session_list.head);
112 return ltt_session_list.next_uuid++;
113 }
114
115 /*
116 * Delete a ltt_session structure to the global list.
117 *
118 * The caller MUST acquire the session list lock before.
119 */
120 static void del_session_list(struct ltt_session *ls)
121 {
122 assert(ls);
123
124 cds_list_del(&ls->list);
125 }
126
127 /*
128 * Return a pointer to the session list.
129 */
130 struct ltt_session_list *session_get_list(void)
131 {
132 return &ltt_session_list;
133 }
134
135 /*
136 * Returns once the session list is empty.
137 */
138 void session_list_wait_empty(void)
139 {
140 pthread_mutex_lock(&ltt_session_list.lock);
141 while (!cds_list_empty(&ltt_session_list.head)) {
142 pthread_cond_wait(&ltt_session_list.removal_cond,
143 &ltt_session_list.lock);
144 }
145 pthread_mutex_unlock(&ltt_session_list.lock);
146 }
147
148 /*
149 * Acquire session list lock
150 */
151 void session_lock_list(void)
152 {
153 pthread_mutex_lock(&ltt_session_list.lock);
154 }
155
156 /*
157 * Try to acquire session list lock
158 */
159 int session_trylock_list(void)
160 {
161 return pthread_mutex_trylock(&ltt_session_list.lock);
162 }
163
164 /*
165 * Release session list lock
166 */
167 void session_unlock_list(void)
168 {
169 pthread_mutex_unlock(&ltt_session_list.lock);
170 }
171
172 /*
173 * Get the session's consumer destination type.
174 *
175 * The caller must hold the session lock.
176 */
177 enum consumer_dst_type session_get_consumer_destination_type(
178 const struct ltt_session *session)
179 {
180 /*
181 * The output information is duplicated in both of those session types.
182 * Hence, it doesn't matter from which it is retrieved. However, it is
183 * possible for only one of them to be set.
184 */
185 return session->kernel_session ?
186 session->kernel_session->consumer->type :
187 session->ust_session->consumer->type;
188 }
189
190 /*
191 * Get the session's consumer network hostname.
192 * The caller must ensure that the destination is of type "net".
193 *
194 * The caller must hold the session lock.
195 */
196 const char *session_get_net_consumer_hostname(const struct ltt_session *session)
197 {
198 const char *hostname = NULL;
199 const struct consumer_output *output;
200
201 output = session->kernel_session ?
202 session->kernel_session->consumer :
203 session->ust_session->consumer;
204
205 /*
206 * hostname is assumed to be the same for both control and data
207 * connections.
208 */
209 switch (output->dst.net.control.dtype) {
210 case LTTNG_DST_IPV4:
211 hostname = output->dst.net.control.dst.ipv4;
212 break;
213 case LTTNG_DST_IPV6:
214 hostname = output->dst.net.control.dst.ipv6;
215 break;
216 default:
217 abort();
218 }
219 return hostname;
220 }
221
222 /*
223 * Get the session's consumer network control and data ports.
224 * The caller must ensure that the destination is of type "net".
225 *
226 * The caller must hold the session lock.
227 */
228 void session_get_net_consumer_ports(const struct ltt_session *session,
229 uint16_t *control_port, uint16_t *data_port)
230 {
231 const struct consumer_output *output;
232
233 output = session->kernel_session ?
234 session->kernel_session->consumer :
235 session->ust_session->consumer;
236 *control_port = output->dst.net.control.port;
237 *data_port = output->dst.net.data.port;
238 }
239
240 /*
241 * Get the location of the latest trace archive produced by a rotation.
242 *
243 * The caller must hold the session lock.
244 */
245 struct lttng_trace_archive_location *session_get_trace_archive_location(
246 struct ltt_session *session)
247 {
248 struct lttng_trace_archive_location *location = NULL;
249
250 if (session->rotation_state != LTTNG_ROTATION_STATE_COMPLETED) {
251 goto end;
252 }
253
254 switch (session_get_consumer_destination_type(session)) {
255 case CONSUMER_DST_LOCAL:
256 location = lttng_trace_archive_location_local_create(
257 session->rotation_chunk.current_rotate_path);
258 break;
259 case CONSUMER_DST_NET:
260 {
261 const char *hostname;
262 uint16_t control_port, data_port;
263
264 hostname = session_get_net_consumer_hostname(session);
265 session_get_net_consumer_ports(session,
266 &control_port,
267 &data_port);
268 location = lttng_trace_archive_location_relay_create(
269 hostname,
270 LTTNG_TRACE_ARCHIVE_LOCATION_RELAY_PROTOCOL_TYPE_TCP,
271 control_port, data_port,
272 session->rotation_chunk.current_rotate_path);
273 break;
274 }
275 default:
276 abort();
277 }
278 end:
279 return location;
280 }
281
282 /*
283 * Allocate the ltt_sessions_ht_by_id HT.
284 *
285 * The session list lock must be held.
286 */
287 int ltt_sessions_ht_alloc(void)
288 {
289 int ret = 0;
290
291 DBG("Allocating ltt_sessions_ht_by_id");
292 ltt_sessions_ht_by_id = lttng_ht_new(0, LTTNG_HT_TYPE_U64);
293 if (!ltt_sessions_ht_by_id) {
294 ret = -1;
295 ERR("Failed to allocate ltt_sessions_ht_by_id");
296 goto end;
297 }
298 end:
299 return ret;
300 }
301
302 /*
303 * Destroy the ltt_sessions_ht_by_id HT.
304 *
305 * The session list lock must be held.
306 */
307 static void ltt_sessions_ht_destroy(void)
308 {
309 if (!ltt_sessions_ht_by_id) {
310 return;
311 }
312 ht_cleanup_push(ltt_sessions_ht_by_id);
313 ltt_sessions_ht_by_id = NULL;
314 }
315
316 /*
317 * Add a ltt_session to the ltt_sessions_ht_by_id.
318 * If unallocated, the ltt_sessions_ht_by_id HT is allocated.
319 * The session list lock must be held.
320 */
321 static void add_session_ht(struct ltt_session *ls)
322 {
323 int ret;
324
325 assert(ls);
326
327 if (!ltt_sessions_ht_by_id) {
328 ret = ltt_sessions_ht_alloc();
329 if (ret) {
330 ERR("Error allocating the sessions HT");
331 goto end;
332 }
333 }
334 lttng_ht_node_init_u64(&ls->node, ls->id);
335 lttng_ht_add_unique_u64(ltt_sessions_ht_by_id, &ls->node);
336
337 end:
338 return;
339 }
340
341 /*
342 * Test if ltt_sessions_ht_by_id is empty.
343 * Return 1 if empty, 0 if not empty.
344 * The session list lock must be held.
345 */
346 static int ltt_sessions_ht_empty(void)
347 {
348 int ret;
349
350 if (!ltt_sessions_ht_by_id) {
351 ret = 1;
352 goto end;
353 }
354
355 ret = lttng_ht_get_count(ltt_sessions_ht_by_id) ? 0 : 1;
356 end:
357 return ret;
358 }
359
360 /*
361 * Remove a ltt_session from the ltt_sessions_ht_by_id.
362 * If empty, the ltt_sessions_ht_by_id HT is freed.
363 * The session list lock must be held.
364 */
365 static void del_session_ht(struct ltt_session *ls)
366 {
367 struct lttng_ht_iter iter;
368 int ret;
369
370 assert(ls);
371 assert(ltt_sessions_ht_by_id);
372
373 iter.iter.node = &ls->node.node;
374 ret = lttng_ht_del(ltt_sessions_ht_by_id, &iter);
375 assert(!ret);
376
377 if (ltt_sessions_ht_empty()) {
378 DBG("Empty ltt_sessions_ht_by_id, destroying it");
379 ltt_sessions_ht_destroy();
380 }
381 }
382
383 /*
384 * Acquire session lock
385 */
386 void session_lock(struct ltt_session *session)
387 {
388 assert(session);
389
390 pthread_mutex_lock(&session->lock);
391 }
392
393 /*
394 * Release session lock
395 */
396 void session_unlock(struct ltt_session *session)
397 {
398 assert(session);
399
400 pthread_mutex_unlock(&session->lock);
401 }
402
403 static
404 void session_release(struct urcu_ref *ref)
405 {
406 int ret;
407 struct ltt_ust_session *usess;
408 struct ltt_kernel_session *ksess;
409 struct ltt_session *session = container_of(ref, typeof(*session), ref);
410
411 usess = session->ust_session;
412 ksess = session->kernel_session;
413
414 /* Clean kernel session teardown */
415 kernel_destroy_session(ksess);
416
417 /* UST session teardown */
418 if (usess) {
419 /* Close any relayd session */
420 consumer_output_send_destroy_relayd(usess->consumer);
421
422 /* Destroy every UST application related to this session. */
423 ret = ust_app_destroy_trace_all(usess);
424 if (ret) {
425 ERR("Error in ust_app_destroy_trace_all");
426 }
427
428 /* Clean up the rest. */
429 trace_ust_destroy_session(usess);
430 }
431
432 /*
433 * Must notify the kernel thread here to update it's poll set in order to
434 * remove the channel(s)' fd just destroyed.
435 */
436 ret = notify_thread_pipe(kernel_poll_pipe[1]);
437 if (ret < 0) {
438 PERROR("write kernel poll pipe");
439 }
440
441 DBG("Destroying session %s (id %" PRIu64 ")", session->name, session->id);
442 pthread_mutex_destroy(&session->lock);
443
444 consumer_output_put(session->consumer);
445 snapshot_destroy(&session->snapshot);
446
447 ASSERT_LOCKED(ltt_session_list.lock);
448 del_session_list(session);
449 del_session_ht(session);
450 pthread_cond_broadcast(&ltt_session_list.removal_cond);
451 free(session);
452 }
453
454 /*
455 * Acquire a reference to a session.
456 * This function may fail (return false); its return value must be checked.
457 */
458 bool session_get(struct ltt_session *session)
459 {
460 return urcu_ref_get_unless_zero(&session->ref);
461 }
462
463 /*
464 * Release a reference to a session.
465 */
466 void session_put(struct ltt_session *session)
467 {
468 /*
469 * The session list lock must be held as any session_put()
470 * may cause the removal of the session from the session_list.
471 */
472 ASSERT_LOCKED(ltt_session_list.lock);
473 assert(session->ref.refcount);
474 urcu_ref_put(&session->ref, session_release);
475 }
476
477 /*
478 * Destroy a session.
479 *
480 * This method does not immediately release/free the session as other
481 * components may still hold a reference to the session. However,
482 * the session should no longer be presented to the user.
483 *
484 * Releases the session list's reference to the session
485 * and marks it as destroyed. Iterations on the session list should be
486 * mindful of the "destroyed" flag.
487 */
488 void session_destroy(struct ltt_session *session)
489 {
490 assert(!session->destroyed);
491 session->destroyed = true;
492 session_put(session);
493 }
494
495 /*
496 * Return a ltt_session structure ptr that matches name. If no session found,
497 * NULL is returned. This must be called with the session list lock held using
498 * session_lock_list and session_unlock_list.
499 * A reference to the session is implicitly acquired by this function.
500 */
501 struct ltt_session *session_find_by_name(const char *name)
502 {
503 struct ltt_session *iter;
504
505 assert(name);
506 ASSERT_LOCKED(ltt_session_list.lock);
507
508 DBG2("Trying to find session by name %s", name);
509
510 cds_list_for_each_entry(iter, &ltt_session_list.head, list) {
511 if (!strncmp(iter->name, name, NAME_MAX) &&
512 !iter->destroyed) {
513 goto found;
514 }
515 }
516
517 return NULL;
518 found:
519 return session_get(iter) ? iter : NULL;
520 }
521
522 /*
523 * Return an ltt_session that matches the id. If no session is found,
524 * NULL is returned. This must be called with rcu_read_lock and
525 * session list lock held (to guarantee the lifetime of the session).
526 */
527 struct ltt_session *session_find_by_id(uint64_t id)
528 {
529 struct lttng_ht_node_u64 *node;
530 struct lttng_ht_iter iter;
531 struct ltt_session *ls;
532
533 ASSERT_LOCKED(ltt_session_list.lock);
534
535 if (!ltt_sessions_ht_by_id) {
536 goto end;
537 }
538
539 lttng_ht_lookup(ltt_sessions_ht_by_id, &id, &iter);
540 node = lttng_ht_iter_get_node_u64(&iter);
541 if (node == NULL) {
542 goto end;
543 }
544 ls = caa_container_of(node, struct ltt_session, node);
545
546 DBG3("Session %" PRIu64 " found by id.", id);
547 return session_get(ls) ? ls : NULL;
548
549 end:
550 DBG3("Session %" PRIu64 " NOT found by id", id);
551 return NULL;
552 }
553
554 /*
555 * Create a brand new session and add it to the session list.
556 */
557 int session_create(char *name, uid_t uid, gid_t gid)
558 {
559 int ret;
560 struct ltt_session *new_session;
561
562 /* Allocate session data structure */
563 new_session = zmalloc(sizeof(struct ltt_session));
564 if (new_session == NULL) {
565 PERROR("zmalloc");
566 ret = LTTNG_ERR_FATAL;
567 goto error_malloc;
568 }
569
570 urcu_ref_init(&new_session->ref);
571
572 /* Define session name */
573 if (name != NULL) {
574 if (snprintf(new_session->name, NAME_MAX, "%s", name) < 0) {
575 ret = LTTNG_ERR_FATAL;
576 goto error_asprintf;
577 }
578 } else {
579 ERR("No session name given");
580 ret = LTTNG_ERR_FATAL;
581 goto error;
582 }
583
584 ret = validate_name(name);
585 if (ret < 0) {
586 ret = LTTNG_ERR_SESSION_INVALID_CHAR;
587 goto error;
588 }
589
590 ret = gethostname(new_session->hostname, sizeof(new_session->hostname));
591 if (ret < 0) {
592 if (errno == ENAMETOOLONG) {
593 new_session->hostname[sizeof(new_session->hostname) - 1] = '\0';
594 } else {
595 ret = LTTNG_ERR_FATAL;
596 goto error;
597 }
598 }
599
600 /* Init kernel session */
601 new_session->kernel_session = NULL;
602 new_session->ust_session = NULL;
603
604 /* Init lock */
605 pthread_mutex_init(&new_session->lock, NULL);
606
607 new_session->uid = uid;
608 new_session->gid = gid;
609
610 ret = snapshot_init(&new_session->snapshot);
611 if (ret < 0) {
612 ret = LTTNG_ERR_NOMEM;
613 goto error;
614 }
615
616 new_session->rotation_pending_local = false;
617 new_session->rotation_pending_relay = false;
618 new_session->rotation_state = LTTNG_ROTATION_STATE_NO_ROTATION;
619
620 new_session->rotation_pending_check_timer_enabled = false;
621 new_session->rotation_schedule_timer_enabled = false;
622
623 /* Add new session to the session list */
624 session_lock_list();
625 new_session->id = add_session_list(new_session);
626 /*
627 * Add the new session to the ltt_sessions_ht_by_id.
628 * No ownership is taken by the hash table; it is merely
629 * a wrapper around the session list used for faster access
630 * by session id.
631 */
632 add_session_ht(new_session);
633 session_unlock_list();
634
635 /*
636 * Consumer is let to NULL since the create_session_uri command will set it
637 * up and, if valid, assign it to the session.
638 */
639 DBG("Tracing session %s created with ID %" PRIu64 " by UID %d GID %d",
640 name, new_session->id, new_session->uid, new_session->gid);
641
642 return LTTNG_OK;
643
644 error:
645 error_asprintf:
646 free(new_session);
647
648 error_malloc:
649 return ret;
650 }
651
652 /*
653 * Check if the UID or GID match the session. Root user has access to all
654 * sessions.
655 */
656 int session_access_ok(struct ltt_session *session, uid_t uid, gid_t gid)
657 {
658 assert(session);
659
660 if (uid != session->uid && gid != session->gid && uid != 0) {
661 return 0;
662 } else {
663 return 1;
664 }
665 }
666
667 /*
668 * Set a session's rotation state and reset all associated state.
669 *
670 * This function resets the rotation state (check timers, pending
671 * flags, etc.) and sets the result of the last rotation. The result
672 * can be queries by a liblttng-ctl client.
673 *
674 * Be careful of the result passed to this function. For instance,
675 * on failure to launch a rotation, a client will expect the rotation
676 * state to be set to "NO_ROTATION". If an error occured while the
677 * rotation was "ONGOING", result should be set to "ERROR", which will
678 * allow a client to report it.
679 *
680 * Must be called with the session and session_list locks held.
681 */
682 int session_reset_rotation_state(struct ltt_session *session,
683 enum lttng_rotation_state result)
684 {
685 int ret = 0;
686
687 ASSERT_LOCKED(ltt_session_list.lock);
688 ASSERT_LOCKED(session->lock);
689
690 session->rotation_pending_local = false;
691 session->rotation_pending_relay = false;
692 session->rotated_after_last_stop = false;
693 session->rotation_state = result;
694 if (session->rotation_pending_check_timer_enabled) {
695 ret = timer_session_rotation_pending_check_stop(session);
696 }
697 return ret;
698 }
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