2 * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
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.h>
14 #include <common/macros.h>
18 #include "testpoint.h"
20 #include "health-sessiond.h"
21 #include "lttng-sessiond.h"
24 struct thread_notifiers
{
25 struct ust_cmd_queue
*ust_cmd_queue
;
26 int apps_cmd_pipe_write_fd
;
27 int apps_cmd_notify_pipe_write_fd
;
28 int dispatch_thread_exit
;
32 * For each tracing session, update newly registered apps. The session list
33 * lock MUST be acquired before calling this.
35 static void update_ust_app(int app_sock
)
37 struct ltt_session
*sess
, *stmp
;
38 const struct ltt_session_list
*session_list
= session_get_list();
41 /* Consumer is in an ERROR state. Stop any application update. */
42 if (uatomic_read(&the_ust_consumerd_state
) == CONSUMER_ERROR
) {
43 /* Stop the update process since the consumer is dead. */
48 assert(app_sock
>= 0);
49 app
= ust_app_find_by_sock(app_sock
);
52 * Application can be unregistered before so
53 * this is possible hence simply stopping the
56 DBG3("UST app update failed to find app sock %d",
61 /* Update all event notifiers for the app. */
62 ust_app_global_update_event_notifier_rules(app
);
64 /* For all tracing session(s) */
65 cds_list_for_each_entry_safe(sess
, stmp
, &session_list
->head
, list
) {
66 if (!session_get(sess
)) {
70 if (!sess
->active
|| !sess
->ust_session
) {
74 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
= NULL
, *tmp_wait_node
;
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
,
111 &wait_queue
->head
, head
) {
112 assert(wait_node
->app
);
113 ret
= lttng_poll_add(&events
, wait_node
->app
->sock
,
114 LPOLLHUP
| LPOLLERR
);
127 * Poll but don't block so we can quickly identify the faulty events and
128 * clean them afterwards from the wait queue.
130 ret
= lttng_poll_wait(&events
, 0);
136 for (i
= 0; i
< nb_fd
; i
++) {
138 uint32_t revents
= LTTNG_POLL_GETEV(&events
, i
);
139 int pollfd
= LTTNG_POLL_GETFD(&events
, i
);
141 cds_list_for_each_entry_safe(wait_node
, tmp_wait_node
,
142 &wait_queue
->head
, head
) {
143 if (pollfd
== wait_node
->app
->sock
&&
144 (revents
& (LPOLLHUP
| LPOLLERR
))) {
145 cds_list_del(&wait_node
->head
);
147 ust_app_destroy(wait_node
->app
);
150 * Silence warning of use-after-free in
151 * cds_list_for_each_entry_safe which uses
152 * __typeof__(*wait_node).
157 ERR("Unexpected poll events %u for sock %d", revents
, pollfd
);
164 DBG("Wait queue sanitized, %d node were cleaned up", nb_fd
);
168 lttng_poll_clean(&events
);
172 lttng_poll_clean(&events
);
174 ERR("Unable to sanitize wait queue");
179 * Send a socket to a thread This is called from the dispatch UST registration
180 * thread once all sockets are set for the application.
182 * The sock value can be invalid, we don't really care, the thread will handle
183 * it and make the necessary cleanup if so.
185 * On success, return 0 else a negative value being the errno message of the
188 static int send_socket_to_thread(int fd
, int sock
)
193 * It's possible that the FD is set as invalid with -1 concurrently just
194 * before calling this function being a shutdown state of the thread.
201 ret
= lttng_write(fd
, &sock
, sizeof(sock
));
202 if (ret
< sizeof(sock
)) {
203 PERROR("write apps pipe %d", fd
);
210 /* All good. Don't send back the write positive ret value. */
216 static void cleanup_ust_dispatch_thread(void *data
)
222 * Dispatch request from the registration threads to the application
223 * communication thread.
225 static void *thread_dispatch_ust_registration(void *data
)
228 struct cds_wfcq_node
*node
;
229 struct ust_command
*ust_cmd
= NULL
;
230 struct ust_reg_wait_node
*wait_node
= NULL
, *tmp_wait_node
;
231 struct ust_reg_wait_queue wait_queue
= {
234 struct thread_notifiers
*notifiers
= data
;
236 rcu_register_thread();
238 health_register(the_health_sessiond
,
239 HEALTH_SESSIOND_TYPE_APP_REG_DISPATCH
);
241 if (testpoint(sessiond_thread_app_reg_dispatch
)) {
242 goto error_testpoint
;
245 health_code_update();
247 CDS_INIT_LIST_HEAD(&wait_queue
.head
);
249 DBG("[thread] Dispatch UST command started");
252 health_code_update();
254 /* Atomically prepare the queue futex */
255 futex_nto1_prepare(¬ifiers
->ust_cmd_queue
->futex
);
257 if (CMM_LOAD_SHARED(notifiers
->dispatch_thread_exit
)) {
262 struct ust_app
*app
= NULL
;
266 * Make sure we don't have node(s) that have hung up before receiving
267 * the notify socket. This is to clean the list in order to avoid
268 * memory leaks from notify socket that are never seen.
270 sanitize_wait_queue(&wait_queue
);
272 health_code_update();
273 /* Dequeue command for registration */
274 node
= cds_wfcq_dequeue_blocking(
275 ¬ifiers
->ust_cmd_queue
->head
,
276 ¬ifiers
->ust_cmd_queue
->tail
);
278 DBG("Woken up but nothing in the UST command queue");
279 /* Continue thread execution */
283 ust_cmd
= caa_container_of(node
, struct ust_command
, node
);
285 DBG("Dispatching UST registration pid:%d ppid:%d uid:%d"
286 " gid:%d sock:%d name:%s (version %d.%d)",
287 ust_cmd
->reg_msg
.pid
, ust_cmd
->reg_msg
.ppid
,
288 ust_cmd
->reg_msg
.uid
, ust_cmd
->reg_msg
.gid
,
289 ust_cmd
->sock
, ust_cmd
->reg_msg
.name
,
290 ust_cmd
->reg_msg
.major
, ust_cmd
->reg_msg
.minor
);
292 if (ust_cmd
->reg_msg
.type
== LTTNG_UST_CTL_SOCKET_CMD
) {
293 wait_node
= zmalloc(sizeof(*wait_node
));
295 PERROR("zmalloc wait_node dispatch");
296 ret
= close(ust_cmd
->sock
);
298 PERROR("close ust sock dispatch %d", ust_cmd
->sock
);
300 lttng_fd_put(LTTNG_FD_APPS
, 1);
305 CDS_INIT_LIST_HEAD(&wait_node
->head
);
307 /* Create application object if socket is CMD. */
308 wait_node
->app
= ust_app_create(&ust_cmd
->reg_msg
,
310 if (!wait_node
->app
) {
311 ret
= close(ust_cmd
->sock
);
313 PERROR("close ust sock dispatch %d", ust_cmd
->sock
);
315 lttng_fd_put(LTTNG_FD_APPS
, 1);
323 * Add application to the wait queue so we can set the notify
324 * socket before putting this object in the global ht.
326 cds_list_add(&wait_node
->head
, &wait_queue
.head
);
332 * We have to continue here since we don't have the notify
333 * socket and the application MUST be added to the hash table
334 * only at that moment.
339 * Look for the application in the local wait queue and set the
340 * notify socket if found.
342 cds_list_for_each_entry_safe(wait_node
, tmp_wait_node
,
343 &wait_queue
.head
, head
) {
344 health_code_update();
345 if (wait_node
->app
->pid
== ust_cmd
->reg_msg
.pid
) {
346 wait_node
->app
->notify_sock
= ust_cmd
->sock
;
347 cds_list_del(&wait_node
->head
);
349 app
= wait_node
->app
;
352 DBG3("UST app notify socket %d is set", ust_cmd
->sock
);
358 * With no application at this stage the received socket is
359 * basically useless so close it before we free the cmd data
360 * structure for good.
363 ret
= close(ust_cmd
->sock
);
365 PERROR("close ust sock dispatch %d", ust_cmd
->sock
);
367 lttng_fd_put(LTTNG_FD_APPS
, 1);
377 * Lock the global session list so from the register up to the
378 * registration done message, no thread can see the application
379 * and change its state.
385 * Add application to the global hash table. This needs to be
386 * done before the update to the UST registry can locate the
391 /* Set app version. This call will print an error if needed. */
392 (void) ust_app_version(app
);
394 (void) ust_app_setup_event_notifier_group(app
);
396 /* Send notify socket through the notify pipe. */
397 ret
= send_socket_to_thread(
398 notifiers
->apps_cmd_notify_pipe_write_fd
,
402 session_unlock_list();
404 * No notify thread, stop the UST tracing. However, this is
405 * not an internal error of the this thread thus setting
406 * the health error code to a normal exit.
413 * Update newly registered application with the tracing
414 * registry info already enabled information.
416 update_ust_app(app
->sock
);
419 * Don't care about return value. Let the manage apps threads
420 * handle app unregistration upon socket close.
422 (void) ust_app_register_done(app
);
425 * Even if the application socket has been closed, send the app
426 * to the thread and unregistration will take place at that
429 ret
= send_socket_to_thread(
430 notifiers
->apps_cmd_pipe_write_fd
,
434 session_unlock_list();
436 * No apps. thread, stop the UST tracing. However, this is
437 * not an internal error of the this thread thus setting
438 * the health error code to a normal exit.
445 session_unlock_list();
447 } while (node
!= NULL
);
450 /* Futex wait on queue. Blocking call on futex() */
451 futex_nto1_wait(¬ifiers
->ust_cmd_queue
->futex
);
454 /* Normal exit, no error */
458 /* Clean up wait queue. */
459 cds_list_for_each_entry_safe(wait_node
, tmp_wait_node
,
460 &wait_queue
.head
, head
) {
461 cds_list_del(&wait_node
->head
);
466 /* Empty command queue. */
468 /* Dequeue command for registration */
469 node
= cds_wfcq_dequeue_blocking(
470 ¬ifiers
->ust_cmd_queue
->head
,
471 ¬ifiers
->ust_cmd_queue
->tail
);
475 ust_cmd
= caa_container_of(node
, struct ust_command
, node
);
476 ret
= close(ust_cmd
->sock
);
478 PERROR("close ust sock exit dispatch %d", ust_cmd
->sock
);
480 lttng_fd_put(LTTNG_FD_APPS
, 1);
485 DBG("Dispatch thread dying");
488 ERR("Health error occurred in %s", __func__
);
490 health_unregister(the_health_sessiond
);
491 rcu_unregister_thread();
495 static bool shutdown_ust_dispatch_thread(void *data
)
497 struct thread_notifiers
*notifiers
= data
;
499 CMM_STORE_SHARED(notifiers
->dispatch_thread_exit
, 1);
500 futex_nto1_wake(¬ifiers
->ust_cmd_queue
->futex
);
504 bool launch_ust_dispatch_thread(struct ust_cmd_queue
*cmd_queue
,
505 int apps_cmd_pipe_write_fd
,
506 int apps_cmd_notify_pipe_write_fd
)
508 struct lttng_thread
*thread
;
509 struct thread_notifiers
*notifiers
;
511 notifiers
= zmalloc(sizeof(*notifiers
));
515 notifiers
->ust_cmd_queue
= cmd_queue
;
516 notifiers
->apps_cmd_pipe_write_fd
= apps_cmd_pipe_write_fd
;
517 notifiers
->apps_cmd_notify_pipe_write_fd
= apps_cmd_notify_pipe_write_fd
;
519 thread
= lttng_thread_create("UST registration dispatch",
520 thread_dispatch_ust_registration
,
521 shutdown_ust_dispatch_thread
,
522 cleanup_ust_dispatch_thread
,
527 lttng_thread_put(thread
);