2 * Copyright (C) 2011 EfficiOS Inc.
3 * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
4 * Copyright (C) 2013 Jérémie Galarneau <jeremie.galarneau@efficios.com>
6 * SPDX-License-Identifier: GPL-2.0-only
10 #include "dispatch.hpp"
11 #include "fd-limit.hpp"
12 #include "health-sessiond.hpp"
13 #include "lttng-sessiond.hpp"
14 #include "testpoint.hpp"
16 #include "ust-app.hpp"
18 #include <common/futex.hpp>
19 #include <common/macros.hpp>
20 #include <common/urcu.hpp>
27 struct thread_notifiers
{
28 struct ust_cmd_queue
*ust_cmd_queue
;
29 int apps_cmd_pipe_write_fd
;
30 int apps_cmd_notify_pipe_write_fd
;
31 int dispatch_thread_exit
;
36 * For each tracing session, update newly registered apps. The session list
37 * lock MUST be acquired before calling this.
39 static void update_ust_app(int app_sock
)
41 struct ltt_session
*sess
, *stmp
;
42 const struct ltt_session_list
*session_list
= session_get_list();
45 /* Consumer is in an ERROR state. Stop any application update. */
46 if (uatomic_read(&the_ust_consumerd_state
) == CONSUMER_ERROR
) {
47 /* Stop the update process since the consumer is dead. */
51 lttng::urcu::read_lock_guard read_lock
;
52 LTTNG_ASSERT(app_sock
>= 0);
53 app
= ust_app_find_by_sock(app_sock
);
56 * Application can be unregistered before so
57 * this is possible hence simply stopping the
60 DBG3("UST app update failed to find app sock %d", app_sock
);
64 /* Update all event notifiers for the app. */
65 ust_app_global_update_event_notifier_rules(app
);
67 /* For all tracing session(s) */
68 cds_list_for_each_entry_safe (sess
, stmp
, &session_list
->head
, list
) {
69 if (!session_get(sess
)) {
73 if (!sess
->active
|| !sess
->ust_session
|| !sess
->ust_session
->active
) {
77 ust_app_global_update(sess
->ust_session
, app
);
85 * Sanitize the wait queue of the dispatch registration thread meaning removing
86 * invalid nodes from it. This is to avoid memory leaks for the case the UST
87 * notify socket is never received.
89 static void sanitize_wait_queue(struct ust_reg_wait_queue
*wait_queue
)
91 int ret
, nb_fd
= 0, i
;
92 unsigned int fd_added
= 0;
93 struct lttng_poll_event events
;
94 struct ust_reg_wait_node
*wait_node
= nullptr, *tmp_wait_node
;
96 LTTNG_ASSERT(wait_queue
);
98 lttng_poll_init(&events
);
100 /* Just skip everything for an empty queue. */
101 if (!wait_queue
->count
) {
105 ret
= lttng_poll_create(&events
, wait_queue
->count
, LTTNG_CLOEXEC
);
110 cds_list_for_each_entry_safe (wait_node
, tmp_wait_node
, &wait_queue
->head
, head
) {
111 LTTNG_ASSERT(wait_node
->app
);
112 ret
= lttng_poll_add(&events
, wait_node
->app
->sock
, LPOLLIN
);
125 * Poll but don't block so we can quickly identify the faulty events and
126 * clean them afterwards from the wait queue.
128 ret
= lttng_poll_wait(&events
, 0);
134 for (i
= 0; i
< nb_fd
; i
++) {
136 uint32_t revents
= LTTNG_POLL_GETEV(&events
, i
);
137 int pollfd
= LTTNG_POLL_GETFD(&events
, i
);
139 cds_list_for_each_entry_safe (wait_node
, tmp_wait_node
, &wait_queue
->head
, head
) {
140 if (pollfd
== wait_node
->app
->sock
&& (revents
& (LPOLLHUP
| LPOLLERR
))) {
141 cds_list_del(&wait_node
->head
);
143 ust_app_destroy(wait_node
->app
);
146 * Silence warning of use-after-free in
147 * cds_list_for_each_entry_safe which uses
148 * __typeof__(*wait_node).
153 ERR("Unexpected poll events %u for sock %d", revents
, pollfd
);
160 DBG("Wait queue sanitized, %d node were cleaned up", nb_fd
);
164 lttng_poll_clean(&events
);
168 lttng_poll_clean(&events
);
170 ERR("Unable to sanitize wait queue");
175 * Send a socket to a thread This is called from the dispatch UST registration
176 * thread once all sockets are set for the application.
178 * The sock value can be invalid, we don't really care, the thread will handle
179 * it and make the necessary cleanup if so.
181 * On success, return 0 else a negative value being the errno message of the
184 static int send_socket_to_thread(int fd
, int sock
)
189 * It's possible that the FD is set as invalid with -1 concurrently just
190 * before calling this function being a shutdown state of the thread.
197 ret
= lttng_write(fd
, &sock
, sizeof(sock
));
198 if (ret
< sizeof(sock
)) {
199 PERROR("write apps pipe %d", fd
);
206 /* All good. Don't send back the write positive ret value. */
212 static void cleanup_ust_dispatch_thread(void *data
)
218 * Dispatch request from the registration threads to the application
219 * communication thread.
221 static void *thread_dispatch_ust_registration(void *data
)
224 struct cds_wfcq_node
*node
;
225 struct ust_command
*ust_cmd
= nullptr;
226 struct ust_reg_wait_node
*wait_node
= nullptr, *tmp_wait_node
;
227 struct ust_reg_wait_queue wait_queue
= {
231 struct thread_notifiers
*notifiers
= (thread_notifiers
*) data
;
233 rcu_register_thread();
235 health_register(the_health_sessiond
, HEALTH_SESSIOND_TYPE_APP_REG_DISPATCH
);
237 if (testpoint(sessiond_thread_app_reg_dispatch
)) {
238 goto error_testpoint
;
241 health_code_update();
243 CDS_INIT_LIST_HEAD(&wait_queue
.head
);
245 DBG("[thread] Dispatch UST command started");
248 health_code_update();
250 /* Atomically prepare the queue futex */
251 futex_nto1_prepare(¬ifiers
->ust_cmd_queue
->futex
);
253 if (CMM_LOAD_SHARED(notifiers
->dispatch_thread_exit
)) {
258 struct ust_app
*app
= nullptr;
262 * Make sure we don't have node(s) that have hung up before receiving
263 * the notify socket. This is to clean the list in order to avoid
264 * memory leaks from notify socket that are never seen.
266 sanitize_wait_queue(&wait_queue
);
268 health_code_update();
269 /* Dequeue command for registration */
270 node
= cds_wfcq_dequeue_blocking(¬ifiers
->ust_cmd_queue
->head
,
271 ¬ifiers
->ust_cmd_queue
->tail
);
272 if (node
== nullptr) {
273 DBG("Woken up but nothing in the UST command queue");
274 /* Continue thread execution */
278 ust_cmd
= lttng::utils::container_of(node
, &ust_command::node
);
280 DBG("Dispatching UST registration pid:%d ppid:%d uid:%d"
281 " gid:%d sock:%d name:%s (version %d.%d)",
282 ust_cmd
->reg_msg
.pid
,
283 ust_cmd
->reg_msg
.ppid
,
284 ust_cmd
->reg_msg
.uid
,
285 ust_cmd
->reg_msg
.gid
,
287 ust_cmd
->reg_msg
.name
,
288 ust_cmd
->reg_msg
.major
,
289 ust_cmd
->reg_msg
.minor
);
291 if (ust_cmd
->reg_msg
.type
== LTTNG_UST_CTL_SOCKET_CMD
) {
292 wait_node
= zmalloc
<ust_reg_wait_node
>();
294 PERROR("zmalloc wait_node dispatch");
295 ret
= close(ust_cmd
->sock
);
297 PERROR("close ust sock dispatch %d", ust_cmd
->sock
);
299 lttng_fd_put(LTTNG_FD_APPS
, 1);
304 CDS_INIT_LIST_HEAD(&wait_node
->head
);
306 /* Create application object if socket is CMD. */
307 wait_node
->app
= ust_app_create(&ust_cmd
->reg_msg
, ust_cmd
->sock
);
308 if (!wait_node
->app
) {
309 ret
= close(ust_cmd
->sock
);
311 PERROR("close ust sock dispatch %d", ust_cmd
->sock
);
313 lttng_fd_put(LTTNG_FD_APPS
, 1);
321 * Add application to the wait queue so we can set the notify
322 * socket before putting this object in the global ht.
324 cds_list_add(&wait_node
->head
, &wait_queue
.head
);
330 * We have to continue here since we don't have the notify
331 * socket and the application MUST be added to the hash table
332 * only at that moment.
337 * Look for the application in the local wait queue and set the
338 * notify socket if found.
340 cds_list_for_each_entry_safe (
341 wait_node
, tmp_wait_node
, &wait_queue
.head
, head
) {
342 health_code_update();
343 if (wait_node
->app
->pid
== ust_cmd
->reg_msg
.pid
) {
344 wait_node
->app
->notify_sock
= ust_cmd
->sock
;
345 cds_list_del(&wait_node
->head
);
347 app
= wait_node
->app
;
350 DBG3("UST app notify socket %d is set",
357 * With no application at this stage the received socket is
358 * basically useless so close it before we free the cmd data
359 * structure for good.
362 ret
= close(ust_cmd
->sock
);
364 PERROR("close ust sock dispatch %d", ust_cmd
->sock
);
366 lttng_fd_put(LTTNG_FD_APPS
, 1);
376 * Lock the global session list so from the register up to the
377 * registration done message, no thread can see the application
378 * and change its state.
381 lttng::urcu::read_lock_guard read_lock
;
384 * Add application to the global hash table. This needs to be
385 * done before the update to the UST registry can locate the
390 /* Set app version. This call will print an error if needed. */
391 (void) ust_app_version(app
);
393 (void) ust_app_setup_event_notifier_group(app
);
395 /* Send notify socket through the notify pipe. */
396 ret
= send_socket_to_thread(
397 notifiers
->apps_cmd_notify_pipe_write_fd
, app
->notify_sock
);
399 session_unlock_list();
401 * No notify thread, stop the UST tracing. However, this is
402 * not an internal error of the this thread thus setting
403 * the health error code to a normal exit.
410 * Update newly registered application with the tracing
411 * registry info already enabled information.
413 update_ust_app(app
->sock
);
416 * Don't care about return value. Let the manage apps threads
417 * handle app unregistration upon socket close.
419 (void) ust_app_register_done(app
);
422 * Even if the application socket has been closed, send the app
423 * to the thread and unregistration will take place at that
426 ret
= send_socket_to_thread(notifiers
->apps_cmd_pipe_write_fd
,
429 session_unlock_list();
431 * No apps. thread, stop the UST tracing. However, this is
432 * not an internal error of the this thread thus setting
433 * the health error code to a normal exit.
439 session_unlock_list();
441 } while (node
!= nullptr);
444 /* Futex wait on queue. Blocking call on futex() */
445 futex_nto1_wait(¬ifiers
->ust_cmd_queue
->futex
);
448 /* Normal exit, no error */
452 /* Clean up wait queue. */
453 cds_list_for_each_entry_safe (wait_node
, tmp_wait_node
, &wait_queue
.head
, head
) {
454 cds_list_del(&wait_node
->head
);
459 /* Empty command queue. */
461 /* Dequeue command for registration */
462 node
= cds_wfcq_dequeue_blocking(¬ifiers
->ust_cmd_queue
->head
,
463 ¬ifiers
->ust_cmd_queue
->tail
);
464 if (node
== nullptr) {
467 ust_cmd
= lttng::utils::container_of(node
, &ust_command::node
);
468 ret
= close(ust_cmd
->sock
);
470 PERROR("close ust sock exit dispatch %d", ust_cmd
->sock
);
472 lttng_fd_put(LTTNG_FD_APPS
, 1);
477 DBG("Dispatch thread dying");
480 ERR("Health error occurred in %s", __func__
);
482 health_unregister(the_health_sessiond
);
483 rcu_unregister_thread();
487 static bool shutdown_ust_dispatch_thread(void *data
)
489 struct thread_notifiers
*notifiers
= (thread_notifiers
*) data
;
491 CMM_STORE_SHARED(notifiers
->dispatch_thread_exit
, 1);
492 futex_nto1_wake(¬ifiers
->ust_cmd_queue
->futex
);
496 bool launch_ust_dispatch_thread(struct ust_cmd_queue
*cmd_queue
,
497 int apps_cmd_pipe_write_fd
,
498 int apps_cmd_notify_pipe_write_fd
)
500 struct lttng_thread
*thread
;
501 struct thread_notifiers
*notifiers
;
503 notifiers
= zmalloc
<thread_notifiers
>();
507 notifiers
->ust_cmd_queue
= cmd_queue
;
508 notifiers
->apps_cmd_pipe_write_fd
= apps_cmd_pipe_write_fd
;
509 notifiers
->apps_cmd_notify_pipe_write_fd
= apps_cmd_notify_pipe_write_fd
;
511 thread
= lttng_thread_create("UST registration dispatch",
512 thread_dispatch_ust_registration
,
513 shutdown_ust_dispatch_thread
,
514 cleanup_ust_dispatch_thread
,
519 lttng_thread_put(thread
);