Launch the ust registration dispatch thread using lttng_thread
[lttng-tools.git] / src / bin / lttng-sessiond / dispatch.c
1 /*
2 * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
3 * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
4 * 2013 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License, version 2 only,
8 * as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License along
16 * with this program; if not, write to the Free Software Foundation, Inc.,
17 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
18 */
19
20 #include <stddef.h>
21 #include <stdlib.h>
22 #include <urcu.h>
23 #include <common/futex.h>
24 #include <common/macros.h>
25
26 #include "dispatch.h"
27 #include "ust-app.h"
28 #include "testpoint.h"
29 #include "fd-limit.h"
30 #include "health-sessiond.h"
31 #include "lttng-sessiond.h"
32 #include "thread.h"
33
34 struct thread_notifiers {
35 struct ust_cmd_queue *ust_cmd_queue;
36 int apps_cmd_pipe_write_fd;
37 int apps_cmd_notify_pipe_write_fd;
38 int dispatch_thread_exit;
39 };
40
41 /*
42 * For each tracing session, update newly registered apps. The session list
43 * lock MUST be acquired before calling this.
44 */
45 static void update_ust_app(int app_sock)
46 {
47 struct ltt_session *sess, *stmp;
48 const struct ltt_session_list *session_list = session_get_list();
49
50 /* Consumer is in an ERROR state. Stop any application update. */
51 if (uatomic_read(&ust_consumerd_state) == CONSUMER_ERROR) {
52 /* Stop the update process since the consumer is dead. */
53 return;
54 }
55
56 /* For all tracing session(s) */
57 cds_list_for_each_entry_safe(sess, stmp, &session_list->head, list) {
58 struct ust_app *app;
59
60 if (!session_get(sess)) {
61 continue;
62 }
63 session_lock(sess);
64 if (!sess->ust_session) {
65 goto unlock_session;
66 }
67
68 rcu_read_lock();
69 assert(app_sock >= 0);
70 app = ust_app_find_by_sock(app_sock);
71 if (app == NULL) {
72 /*
73 * Application can be unregistered before so
74 * this is possible hence simply stopping the
75 * update.
76 */
77 DBG3("UST app update failed to find app sock %d",
78 app_sock);
79 goto unlock_rcu;
80 }
81 ust_app_global_update(sess->ust_session, app);
82 unlock_rcu:
83 rcu_read_unlock();
84 unlock_session:
85 session_unlock(sess);
86 session_put(sess);
87 }
88 }
89
90 /*
91 * Sanitize the wait queue of the dispatch registration thread meaning removing
92 * invalid nodes from it. This is to avoid memory leaks for the case the UST
93 * notify socket is never received.
94 */
95 static void sanitize_wait_queue(struct ust_reg_wait_queue *wait_queue)
96 {
97 int ret, nb_fd = 0, i;
98 unsigned int fd_added = 0;
99 struct lttng_poll_event events;
100 struct ust_reg_wait_node *wait_node = NULL, *tmp_wait_node;
101
102 assert(wait_queue);
103
104 lttng_poll_init(&events);
105
106 /* Just skip everything for an empty queue. */
107 if (!wait_queue->count) {
108 goto end;
109 }
110
111 ret = lttng_poll_create(&events, wait_queue->count, LTTNG_CLOEXEC);
112 if (ret < 0) {
113 goto error_create;
114 }
115
116 cds_list_for_each_entry_safe(wait_node, tmp_wait_node,
117 &wait_queue->head, head) {
118 assert(wait_node->app);
119 ret = lttng_poll_add(&events, wait_node->app->sock,
120 LPOLLHUP | LPOLLERR);
121 if (ret < 0) {
122 goto error;
123 }
124
125 fd_added = 1;
126 }
127
128 if (!fd_added) {
129 goto end;
130 }
131
132 /*
133 * Poll but don't block so we can quickly identify the faulty events and
134 * clean them afterwards from the wait queue.
135 */
136 ret = lttng_poll_wait(&events, 0);
137 if (ret < 0) {
138 goto error;
139 }
140 nb_fd = ret;
141
142 for (i = 0; i < nb_fd; i++) {
143 /* Get faulty FD. */
144 uint32_t revents = LTTNG_POLL_GETEV(&events, i);
145 int pollfd = LTTNG_POLL_GETFD(&events, i);
146
147 if (!revents) {
148 /* No activity for this FD (poll implementation). */
149 continue;
150 }
151
152 cds_list_for_each_entry_safe(wait_node, tmp_wait_node,
153 &wait_queue->head, head) {
154 if (pollfd == wait_node->app->sock &&
155 (revents & (LPOLLHUP | LPOLLERR))) {
156 cds_list_del(&wait_node->head);
157 wait_queue->count--;
158 ust_app_destroy(wait_node->app);
159 free(wait_node);
160 /*
161 * Silence warning of use-after-free in
162 * cds_list_for_each_entry_safe which uses
163 * __typeof__(*wait_node).
164 */
165 wait_node = NULL;
166 break;
167 } else {
168 ERR("Unexpected poll events %u for sock %d", revents, pollfd);
169 goto error;
170 }
171 }
172 }
173
174 if (nb_fd > 0) {
175 DBG("Wait queue sanitized, %d node were cleaned up", nb_fd);
176 }
177
178 end:
179 lttng_poll_clean(&events);
180 return;
181
182 error:
183 lttng_poll_clean(&events);
184 error_create:
185 ERR("Unable to sanitize wait queue");
186 return;
187 }
188
189 /*
190 * Send a socket to a thread This is called from the dispatch UST registration
191 * thread once all sockets are set for the application.
192 *
193 * The sock value can be invalid, we don't really care, the thread will handle
194 * it and make the necessary cleanup if so.
195 *
196 * On success, return 0 else a negative value being the errno message of the
197 * write().
198 */
199 static int send_socket_to_thread(int fd, int sock)
200 {
201 ssize_t ret;
202
203 /*
204 * It's possible that the FD is set as invalid with -1 concurrently just
205 * before calling this function being a shutdown state of the thread.
206 */
207 if (fd < 0) {
208 ret = -EBADF;
209 goto error;
210 }
211
212 ret = lttng_write(fd, &sock, sizeof(sock));
213 if (ret < sizeof(sock)) {
214 PERROR("write apps pipe %d", fd);
215 if (ret < 0) {
216 ret = -errno;
217 }
218 goto error;
219 }
220
221 /* All good. Don't send back the write positive ret value. */
222 ret = 0;
223 error:
224 return (int) ret;
225 }
226
227 static void cleanup_ust_dispatch_thread(void *data)
228 {
229 free(data);
230 }
231
232 /*
233 * Dispatch request from the registration threads to the application
234 * communication thread.
235 */
236 static void *thread_dispatch_ust_registration(void *data)
237 {
238 int ret, err = -1;
239 struct cds_wfcq_node *node;
240 struct ust_command *ust_cmd = NULL;
241 struct ust_reg_wait_node *wait_node = NULL, *tmp_wait_node;
242 struct ust_reg_wait_queue wait_queue = {
243 .count = 0,
244 };
245 struct thread_notifiers *notifiers = data;
246
247 rcu_register_thread();
248
249 health_register(health_sessiond, HEALTH_SESSIOND_TYPE_APP_REG_DISPATCH);
250
251 if (testpoint(sessiond_thread_app_reg_dispatch)) {
252 goto error_testpoint;
253 }
254
255 health_code_update();
256
257 CDS_INIT_LIST_HEAD(&wait_queue.head);
258
259 DBG("[thread] Dispatch UST command started");
260
261 for (;;) {
262 health_code_update();
263
264 /* Atomically prepare the queue futex */
265 futex_nto1_prepare(&notifiers->ust_cmd_queue->futex);
266
267 if (CMM_LOAD_SHARED(notifiers->dispatch_thread_exit)) {
268 break;
269 }
270
271 do {
272 struct ust_app *app = NULL;
273 ust_cmd = NULL;
274
275 /*
276 * Make sure we don't have node(s) that have hung up before receiving
277 * the notify socket. This is to clean the list in order to avoid
278 * memory leaks from notify socket that are never seen.
279 */
280 sanitize_wait_queue(&wait_queue);
281
282 health_code_update();
283 /* Dequeue command for registration */
284 node = cds_wfcq_dequeue_blocking(
285 &notifiers->ust_cmd_queue->head,
286 &notifiers->ust_cmd_queue->tail);
287 if (node == NULL) {
288 DBG("Woken up but nothing in the UST command queue");
289 /* Continue thread execution */
290 break;
291 }
292
293 ust_cmd = caa_container_of(node, struct ust_command, node);
294
295 DBG("Dispatching UST registration pid:%d ppid:%d uid:%d"
296 " gid:%d sock:%d name:%s (version %d.%d)",
297 ust_cmd->reg_msg.pid, ust_cmd->reg_msg.ppid,
298 ust_cmd->reg_msg.uid, ust_cmd->reg_msg.gid,
299 ust_cmd->sock, ust_cmd->reg_msg.name,
300 ust_cmd->reg_msg.major, ust_cmd->reg_msg.minor);
301
302 if (ust_cmd->reg_msg.type == USTCTL_SOCKET_CMD) {
303 wait_node = zmalloc(sizeof(*wait_node));
304 if (!wait_node) {
305 PERROR("zmalloc wait_node dispatch");
306 ret = close(ust_cmd->sock);
307 if (ret < 0) {
308 PERROR("close ust sock dispatch %d", ust_cmd->sock);
309 }
310 lttng_fd_put(LTTNG_FD_APPS, 1);
311 free(ust_cmd);
312 goto error;
313 }
314 CDS_INIT_LIST_HEAD(&wait_node->head);
315
316 /* Create application object if socket is CMD. */
317 wait_node->app = ust_app_create(&ust_cmd->reg_msg,
318 ust_cmd->sock);
319 if (!wait_node->app) {
320 ret = close(ust_cmd->sock);
321 if (ret < 0) {
322 PERROR("close ust sock dispatch %d", ust_cmd->sock);
323 }
324 lttng_fd_put(LTTNG_FD_APPS, 1);
325 free(wait_node);
326 free(ust_cmd);
327 continue;
328 }
329 /*
330 * Add application to the wait queue so we can set the notify
331 * socket before putting this object in the global ht.
332 */
333 cds_list_add(&wait_node->head, &wait_queue.head);
334 wait_queue.count++;
335
336 free(ust_cmd);
337 /*
338 * We have to continue here since we don't have the notify
339 * socket and the application MUST be added to the hash table
340 * only at that moment.
341 */
342 continue;
343 } else {
344 /*
345 * Look for the application in the local wait queue and set the
346 * notify socket if found.
347 */
348 cds_list_for_each_entry_safe(wait_node, tmp_wait_node,
349 &wait_queue.head, head) {
350 health_code_update();
351 if (wait_node->app->pid == ust_cmd->reg_msg.pid) {
352 wait_node->app->notify_sock = ust_cmd->sock;
353 cds_list_del(&wait_node->head);
354 wait_queue.count--;
355 app = wait_node->app;
356 free(wait_node);
357 DBG3("UST app notify socket %d is set", ust_cmd->sock);
358 break;
359 }
360 }
361
362 /*
363 * With no application at this stage the received socket is
364 * basically useless so close it before we free the cmd data
365 * structure for good.
366 */
367 if (!app) {
368 ret = close(ust_cmd->sock);
369 if (ret < 0) {
370 PERROR("close ust sock dispatch %d", ust_cmd->sock);
371 }
372 lttng_fd_put(LTTNG_FD_APPS, 1);
373 }
374 free(ust_cmd);
375 }
376
377 if (app) {
378 /*
379 * @session_lock_list
380 *
381 * Lock the global session list so from the register up to the
382 * registration done message, no thread can see the application
383 * and change its state.
384 */
385 session_lock_list();
386 rcu_read_lock();
387
388 /*
389 * Add application to the global hash table. This needs to be
390 * done before the update to the UST registry can locate the
391 * application.
392 */
393 ust_app_add(app);
394
395 /* Set app version. This call will print an error if needed. */
396 (void) ust_app_version(app);
397
398 /* Send notify socket through the notify pipe. */
399 ret = send_socket_to_thread(
400 notifiers->apps_cmd_notify_pipe_write_fd,
401 app->notify_sock);
402 if (ret < 0) {
403 rcu_read_unlock();
404 session_unlock_list();
405 /*
406 * No notify thread, stop the UST tracing. However, this is
407 * not an internal error of the this thread thus setting
408 * the health error code to a normal exit.
409 */
410 err = 0;
411 goto error;
412 }
413
414 /*
415 * Update newly registered application with the tracing
416 * registry info already enabled information.
417 */
418 update_ust_app(app->sock);
419
420 /*
421 * Don't care about return value. Let the manage apps threads
422 * handle app unregistration upon socket close.
423 */
424 (void) ust_app_register_done(app);
425
426 /*
427 * Even if the application socket has been closed, send the app
428 * to the thread and unregistration will take place at that
429 * place.
430 */
431 ret = send_socket_to_thread(
432 notifiers->apps_cmd_pipe_write_fd,
433 app->sock);
434 if (ret < 0) {
435 rcu_read_unlock();
436 session_unlock_list();
437 /*
438 * No apps. thread, stop the UST tracing. However, this is
439 * not an internal error of the this thread thus setting
440 * the health error code to a normal exit.
441 */
442 err = 0;
443 goto error;
444 }
445
446 rcu_read_unlock();
447 session_unlock_list();
448 }
449 } while (node != NULL);
450
451 health_poll_entry();
452 /* Futex wait on queue. Blocking call on futex() */
453 futex_nto1_wait(&notifiers->ust_cmd_queue->futex);
454 health_poll_exit();
455 }
456 /* Normal exit, no error */
457 err = 0;
458
459 error:
460 /* Clean up wait queue. */
461 cds_list_for_each_entry_safe(wait_node, tmp_wait_node,
462 &wait_queue.head, head) {
463 cds_list_del(&wait_node->head);
464 wait_queue.count--;
465 free(wait_node);
466 }
467
468 /* Empty command queue. */
469 for (;;) {
470 /* Dequeue command for registration */
471 node = cds_wfcq_dequeue_blocking(
472 &notifiers->ust_cmd_queue->head,
473 &notifiers->ust_cmd_queue->tail);
474 if (node == NULL) {
475 break;
476 }
477 ust_cmd = caa_container_of(node, struct ust_command, node);
478 ret = close(ust_cmd->sock);
479 if (ret < 0) {
480 PERROR("close ust sock exit dispatch %d", ust_cmd->sock);
481 }
482 lttng_fd_put(LTTNG_FD_APPS, 1);
483 free(ust_cmd);
484 }
485
486 error_testpoint:
487 DBG("Dispatch thread dying");
488 if (err) {
489 health_error();
490 ERR("Health error occurred in %s", __func__);
491 }
492 health_unregister(health_sessiond);
493 rcu_unregister_thread();
494 return NULL;
495 }
496
497 static bool shutdown_ust_dispatch_thread(void *data)
498 {
499 struct thread_notifiers *notifiers = data;
500
501 CMM_STORE_SHARED(notifiers->dispatch_thread_exit, 1);
502 futex_nto1_wake(&notifiers->ust_cmd_queue->futex);
503 return true;
504 }
505
506 bool launch_ust_dispatch_thread(struct ust_cmd_queue *cmd_queue,
507 int apps_cmd_pipe_write_fd,
508 int apps_cmd_notify_pipe_write_fd)
509 {
510 struct lttng_thread *thread;
511 struct thread_notifiers *notifiers;
512
513 notifiers = zmalloc(sizeof(*notifiers));
514 if (!notifiers) {
515 goto error;
516 }
517 notifiers->ust_cmd_queue = cmd_queue;
518 notifiers->apps_cmd_pipe_write_fd = apps_cmd_pipe_write_fd;
519 notifiers->apps_cmd_notify_pipe_write_fd = apps_cmd_notify_pipe_write_fd;
520
521 thread = lttng_thread_create("UST registration dispatch",
522 thread_dispatch_ust_registration,
523 shutdown_ust_dispatch_thread,
524 cleanup_ust_dispatch_thread,
525 notifiers);
526 if (!thread) {
527 goto error;
528 }
529 lttng_thread_put(thread);
530 return true;
531 error:
532 free(notifiers);
533 return false;
534 }
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