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
13 #include <common/futex.hpp>
14 #include <common/macros.hpp>
16 #include "dispatch.hpp"
17 #include "ust-app.hpp"
18 #include "testpoint.hpp"
19 #include "fd-limit.hpp"
20 #include "health-sessiond.hpp"
21 #include "lttng-sessiond.hpp"
25 struct thread_notifiers
{
26 struct ust_cmd_queue
*ust_cmd_queue
;
27 int apps_cmd_pipe_write_fd
;
28 int apps_cmd_notify_pipe_write_fd
;
29 int dispatch_thread_exit
;
34 * For each tracing session, update newly registered apps. The session list
35 * lock MUST be acquired before calling this.
37 static void update_ust_app(int app_sock
)
39 struct ltt_session
*sess
, *stmp
;
40 const struct ltt_session_list
*session_list
= session_get_list();
43 /* Consumer is in an ERROR state. Stop any application update. */
44 if (uatomic_read(&the_ust_consumerd_state
) == CONSUMER_ERROR
) {
45 /* Stop the update process since the consumer is dead. */
50 LTTNG_ASSERT(app_sock
>= 0);
51 app
= ust_app_find_by_sock(app_sock
);
54 * Application can be unregistered before so
55 * this is possible hence simply stopping the
58 DBG3("UST app update failed to find app sock %d",
63 /* Update all event notifiers for the app. */
64 ust_app_global_update_event_notifier_rules(app
);
66 /* For all tracing session(s) */
67 cds_list_for_each_entry_safe(sess
, stmp
, &session_list
->head
, list
) {
68 if (!session_get(sess
)) {
72 if (!sess
->active
|| !sess
->ust_session
||
73 !sess
->ust_session
->active
) {
77 ust_app_global_update(sess
->ust_session
, app
);
88 * Sanitize the wait queue of the dispatch registration thread meaning removing
89 * invalid nodes from it. This is to avoid memory leaks for the case the UST
90 * notify socket is never received.
92 static void sanitize_wait_queue(struct ust_reg_wait_queue
*wait_queue
)
94 int ret
, nb_fd
= 0, i
;
95 unsigned int fd_added
= 0;
96 struct lttng_poll_event events
;
97 struct ust_reg_wait_node
*wait_node
= NULL
, *tmp_wait_node
;
99 LTTNG_ASSERT(wait_queue
);
101 lttng_poll_init(&events
);
103 /* Just skip everything for an empty queue. */
104 if (!wait_queue
->count
) {
108 ret
= lttng_poll_create(&events
, wait_queue
->count
, LTTNG_CLOEXEC
);
113 cds_list_for_each_entry_safe(wait_node
, tmp_wait_node
,
114 &wait_queue
->head
, head
) {
115 LTTNG_ASSERT(wait_node
->app
);
116 ret
= lttng_poll_add(&events
, wait_node
->app
->sock
,
117 LPOLLHUP
| LPOLLERR
);
130 * Poll but don't block so we can quickly identify the faulty events and
131 * clean them afterwards from the wait queue.
133 ret
= lttng_poll_wait(&events
, 0);
139 for (i
= 0; i
< nb_fd
; i
++) {
141 uint32_t revents
= LTTNG_POLL_GETEV(&events
, i
);
142 int pollfd
= LTTNG_POLL_GETFD(&events
, i
);
144 cds_list_for_each_entry_safe(wait_node
, tmp_wait_node
,
145 &wait_queue
->head
, head
) {
146 if (pollfd
== wait_node
->app
->sock
&&
147 (revents
& (LPOLLHUP
| LPOLLERR
))) {
148 cds_list_del(&wait_node
->head
);
150 ust_app_destroy(wait_node
->app
);
153 * Silence warning of use-after-free in
154 * cds_list_for_each_entry_safe which uses
155 * __typeof__(*wait_node).
160 ERR("Unexpected poll events %u for sock %d", revents
, pollfd
);
167 DBG("Wait queue sanitized, %d node were cleaned up", nb_fd
);
171 lttng_poll_clean(&events
);
175 lttng_poll_clean(&events
);
177 ERR("Unable to sanitize wait queue");
182 * Send a socket to a thread This is called from the dispatch UST registration
183 * thread once all sockets are set for the application.
185 * The sock value can be invalid, we don't really care, the thread will handle
186 * it and make the necessary cleanup if so.
188 * On success, return 0 else a negative value being the errno message of the
191 static int send_socket_to_thread(int fd
, int sock
)
196 * It's possible that the FD is set as invalid with -1 concurrently just
197 * before calling this function being a shutdown state of the thread.
204 ret
= lttng_write(fd
, &sock
, sizeof(sock
));
205 if (ret
< sizeof(sock
)) {
206 PERROR("write apps pipe %d", fd
);
213 /* All good. Don't send back the write positive ret value. */
219 static void cleanup_ust_dispatch_thread(void *data
)
225 * Dispatch request from the registration threads to the application
226 * communication thread.
228 static void *thread_dispatch_ust_registration(void *data
)
231 struct cds_wfcq_node
*node
;
232 struct ust_command
*ust_cmd
= NULL
;
233 struct ust_reg_wait_node
*wait_node
= NULL
, *tmp_wait_node
;
234 struct ust_reg_wait_queue wait_queue
= {
238 struct thread_notifiers
*notifiers
= (thread_notifiers
*) data
;
240 rcu_register_thread();
242 health_register(the_health_sessiond
,
243 HEALTH_SESSIOND_TYPE_APP_REG_DISPATCH
);
245 if (testpoint(sessiond_thread_app_reg_dispatch
)) {
246 goto error_testpoint
;
249 health_code_update();
251 CDS_INIT_LIST_HEAD(&wait_queue
.head
);
253 DBG("[thread] Dispatch UST command started");
256 health_code_update();
258 /* Atomically prepare the queue futex */
259 futex_nto1_prepare(¬ifiers
->ust_cmd_queue
->futex
);
261 if (CMM_LOAD_SHARED(notifiers
->dispatch_thread_exit
)) {
266 struct ust_app
*app
= NULL
;
270 * Make sure we don't have node(s) that have hung up before receiving
271 * the notify socket. This is to clean the list in order to avoid
272 * memory leaks from notify socket that are never seen.
274 sanitize_wait_queue(&wait_queue
);
276 health_code_update();
277 /* Dequeue command for registration */
278 node
= cds_wfcq_dequeue_blocking(
279 ¬ifiers
->ust_cmd_queue
->head
,
280 ¬ifiers
->ust_cmd_queue
->tail
);
282 DBG("Woken up but nothing in the UST command queue");
283 /* Continue thread execution */
287 ust_cmd
= caa_container_of(node
, struct ust_command
, node
);
289 DBG("Dispatching UST registration pid:%d ppid:%d uid:%d"
290 " gid:%d sock:%d name:%s (version %d.%d)",
291 ust_cmd
->reg_msg
.pid
, ust_cmd
->reg_msg
.ppid
,
292 ust_cmd
->reg_msg
.uid
, ust_cmd
->reg_msg
.gid
,
293 ust_cmd
->sock
, ust_cmd
->reg_msg
.name
,
294 ust_cmd
->reg_msg
.major
, ust_cmd
->reg_msg
.minor
);
296 if (ust_cmd
->reg_msg
.type
== LTTNG_UST_CTL_SOCKET_CMD
) {
297 wait_node
= zmalloc
<ust_reg_wait_node
>();
299 PERROR("zmalloc wait_node dispatch");
300 ret
= close(ust_cmd
->sock
);
302 PERROR("close ust sock dispatch %d", ust_cmd
->sock
);
304 lttng_fd_put(LTTNG_FD_APPS
, 1);
309 CDS_INIT_LIST_HEAD(&wait_node
->head
);
311 /* Create application object if socket is CMD. */
312 wait_node
->app
= ust_app_create(&ust_cmd
->reg_msg
,
314 if (!wait_node
->app
) {
315 ret
= close(ust_cmd
->sock
);
317 PERROR("close ust sock dispatch %d", ust_cmd
->sock
);
319 lttng_fd_put(LTTNG_FD_APPS
, 1);
327 * Add application to the wait queue so we can set the notify
328 * socket before putting this object in the global ht.
330 cds_list_add(&wait_node
->head
, &wait_queue
.head
);
336 * We have to continue here since we don't have the notify
337 * socket and the application MUST be added to the hash table
338 * only at that moment.
343 * Look for the application in the local wait queue and set the
344 * notify socket if found.
346 cds_list_for_each_entry_safe(wait_node
, tmp_wait_node
,
347 &wait_queue
.head
, head
) {
348 health_code_update();
349 if (wait_node
->app
->pid
== ust_cmd
->reg_msg
.pid
) {
350 wait_node
->app
->notify_sock
= ust_cmd
->sock
;
351 cds_list_del(&wait_node
->head
);
353 app
= wait_node
->app
;
356 DBG3("UST app notify socket %d is set", ust_cmd
->sock
);
362 * With no application at this stage the received socket is
363 * basically useless so close it before we free the cmd data
364 * structure for good.
367 ret
= close(ust_cmd
->sock
);
369 PERROR("close ust sock dispatch %d", ust_cmd
->sock
);
371 lttng_fd_put(LTTNG_FD_APPS
, 1);
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.
389 * Add application to the global hash table. This needs to be
390 * done before the update to the UST registry can locate the
395 /* Set app version. This call will print an error if needed. */
396 (void) ust_app_version(app
);
398 (void) ust_app_setup_event_notifier_group(app
);
400 /* Send notify socket through the notify pipe. */
401 ret
= send_socket_to_thread(
402 notifiers
->apps_cmd_notify_pipe_write_fd
,
406 session_unlock_list();
408 * No notify thread, stop the UST tracing. However, this is
409 * not an internal error of the this thread thus setting
410 * the health error code to a normal exit.
417 * Update newly registered application with the tracing
418 * registry info already enabled information.
420 update_ust_app(app
->sock
);
423 * Don't care about return value. Let the manage apps threads
424 * handle app unregistration upon socket close.
426 (void) ust_app_register_done(app
);
429 * Even if the application socket has been closed, send the app
430 * to the thread and unregistration will take place at that
433 ret
= send_socket_to_thread(
434 notifiers
->apps_cmd_pipe_write_fd
,
438 session_unlock_list();
440 * No apps. thread, stop the UST tracing. However, this is
441 * not an internal error of the this thread thus setting
442 * the health error code to a normal exit.
449 session_unlock_list();
451 } while (node
!= NULL
);
454 /* Futex wait on queue. Blocking call on futex() */
455 futex_nto1_wait(¬ifiers
->ust_cmd_queue
->futex
);
458 /* Normal exit, no error */
462 /* Clean up wait queue. */
463 cds_list_for_each_entry_safe(wait_node
, tmp_wait_node
,
464 &wait_queue
.head
, head
) {
465 cds_list_del(&wait_node
->head
);
470 /* Empty command queue. */
472 /* Dequeue command for registration */
473 node
= cds_wfcq_dequeue_blocking(
474 ¬ifiers
->ust_cmd_queue
->head
,
475 ¬ifiers
->ust_cmd_queue
->tail
);
479 ust_cmd
= caa_container_of(node
, struct ust_command
, node
);
480 ret
= close(ust_cmd
->sock
);
482 PERROR("close ust sock exit dispatch %d", ust_cmd
->sock
);
484 lttng_fd_put(LTTNG_FD_APPS
, 1);
489 DBG("Dispatch thread dying");
492 ERR("Health error occurred in %s", __func__
);
494 health_unregister(the_health_sessiond
);
495 rcu_unregister_thread();
499 static bool shutdown_ust_dispatch_thread(void *data
)
501 struct thread_notifiers
*notifiers
= (thread_notifiers
*) data
;
503 CMM_STORE_SHARED(notifiers
->dispatch_thread_exit
, 1);
504 futex_nto1_wake(¬ifiers
->ust_cmd_queue
->futex
);
508 bool launch_ust_dispatch_thread(struct ust_cmd_queue
*cmd_queue
,
509 int apps_cmd_pipe_write_fd
,
510 int apps_cmd_notify_pipe_write_fd
)
512 struct lttng_thread
*thread
;
513 struct thread_notifiers
*notifiers
;
515 notifiers
= zmalloc
<thread_notifiers
>();
519 notifiers
->ust_cmd_queue
= cmd_queue
;
520 notifiers
->apps_cmd_pipe_write_fd
= apps_cmd_pipe_write_fd
;
521 notifiers
->apps_cmd_notify_pipe_write_fd
= apps_cmd_notify_pipe_write_fd
;
523 thread
= lttng_thread_create("UST registration dispatch",
524 thread_dispatch_ust_registration
,
525 shutdown_ust_dispatch_thread
,
526 cleanup_ust_dispatch_thread
,
531 lttng_thread_put(thread
);