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();
40 /* Consumer is in an ERROR state. Stop any application update. */
41 if (uatomic_read(&ust_consumerd_state
) == CONSUMER_ERROR
) {
42 /* Stop the update process since the consumer is dead. */
46 /* For all tracing session(s) */
47 cds_list_for_each_entry_safe(sess
, stmp
, &session_list
->head
, list
) {
50 if (!session_get(sess
)) {
54 if (!sess
->active
|| !sess
->ust_session
) {
59 assert(app_sock
>= 0);
60 app
= ust_app_find_by_sock(app_sock
);
63 * Application can be unregistered before so
64 * this is possible hence simply stopping the
67 DBG3("UST app update failed to find app sock %d",
71 ust_app_global_update(sess
->ust_session
, app
);
81 * Sanitize the wait queue of the dispatch registration thread meaning removing
82 * invalid nodes from it. This is to avoid memory leaks for the case the UST
83 * notify socket is never received.
85 static void sanitize_wait_queue(struct ust_reg_wait_queue
*wait_queue
)
87 int ret
, nb_fd
= 0, i
;
88 unsigned int fd_added
= 0;
89 struct lttng_poll_event events
;
90 struct ust_reg_wait_node
*wait_node
= NULL
, *tmp_wait_node
;
94 lttng_poll_init(&events
);
96 /* Just skip everything for an empty queue. */
97 if (!wait_queue
->count
) {
101 ret
= lttng_poll_create(&events
, wait_queue
->count
, LTTNG_CLOEXEC
);
106 cds_list_for_each_entry_safe(wait_node
, tmp_wait_node
,
107 &wait_queue
->head
, head
) {
108 assert(wait_node
->app
);
109 ret
= lttng_poll_add(&events
, wait_node
->app
->sock
,
110 LPOLLHUP
| LPOLLERR
);
123 * Poll but don't block so we can quickly identify the faulty events and
124 * clean them afterwards from the wait queue.
126 ret
= lttng_poll_wait(&events
, 0);
132 for (i
= 0; i
< nb_fd
; i
++) {
134 uint32_t revents
= LTTNG_POLL_GETEV(&events
, i
);
135 int pollfd
= LTTNG_POLL_GETFD(&events
, i
);
137 cds_list_for_each_entry_safe(wait_node
, tmp_wait_node
,
138 &wait_queue
->head
, head
) {
139 if (pollfd
== wait_node
->app
->sock
&&
140 (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
= NULL
;
226 struct ust_reg_wait_node
*wait_node
= NULL
, *tmp_wait_node
;
227 struct ust_reg_wait_queue wait_queue
= {
230 struct thread_notifiers
*notifiers
= data
;
232 rcu_register_thread();
234 health_register(health_sessiond
, HEALTH_SESSIOND_TYPE_APP_REG_DISPATCH
);
236 if (testpoint(sessiond_thread_app_reg_dispatch
)) {
237 goto error_testpoint
;
240 health_code_update();
242 CDS_INIT_LIST_HEAD(&wait_queue
.head
);
244 DBG("[thread] Dispatch UST command started");
247 health_code_update();
249 /* Atomically prepare the queue futex */
250 futex_nto1_prepare(¬ifiers
->ust_cmd_queue
->futex
);
252 if (CMM_LOAD_SHARED(notifiers
->dispatch_thread_exit
)) {
257 struct ust_app
*app
= NULL
;
261 * Make sure we don't have node(s) that have hung up before receiving
262 * the notify socket. This is to clean the list in order to avoid
263 * memory leaks from notify socket that are never seen.
265 sanitize_wait_queue(&wait_queue
);
267 health_code_update();
268 /* Dequeue command for registration */
269 node
= cds_wfcq_dequeue_blocking(
270 ¬ifiers
->ust_cmd_queue
->head
,
271 ¬ifiers
->ust_cmd_queue
->tail
);
273 DBG("Woken up but nothing in the UST command queue");
274 /* Continue thread execution */
278 ust_cmd
= caa_container_of(node
, struct 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
, ust_cmd
->reg_msg
.ppid
,
283 ust_cmd
->reg_msg
.uid
, ust_cmd
->reg_msg
.gid
,
284 ust_cmd
->sock
, ust_cmd
->reg_msg
.name
,
285 ust_cmd
->reg_msg
.major
, ust_cmd
->reg_msg
.minor
);
287 if (ust_cmd
->reg_msg
.type
== USTCTL_SOCKET_CMD
) {
288 wait_node
= zmalloc(sizeof(*wait_node
));
290 PERROR("zmalloc wait_node dispatch");
291 ret
= close(ust_cmd
->sock
);
293 PERROR("close ust sock dispatch %d", ust_cmd
->sock
);
295 lttng_fd_put(LTTNG_FD_APPS
, 1);
300 CDS_INIT_LIST_HEAD(&wait_node
->head
);
302 /* Create application object if socket is CMD. */
303 wait_node
->app
= ust_app_create(&ust_cmd
->reg_msg
,
305 if (!wait_node
->app
) {
306 ret
= close(ust_cmd
->sock
);
308 PERROR("close ust sock dispatch %d", ust_cmd
->sock
);
310 lttng_fd_put(LTTNG_FD_APPS
, 1);
318 * Add application to the wait queue so we can set the notify
319 * socket before putting this object in the global ht.
321 cds_list_add(&wait_node
->head
, &wait_queue
.head
);
327 * We have to continue here since we don't have the notify
328 * socket and the application MUST be added to the hash table
329 * only at that moment.
334 * Look for the application in the local wait queue and set the
335 * notify socket if found.
337 cds_list_for_each_entry_safe(wait_node
, tmp_wait_node
,
338 &wait_queue
.head
, head
) {
339 health_code_update();
340 if (wait_node
->app
->pid
== ust_cmd
->reg_msg
.pid
) {
341 wait_node
->app
->notify_sock
= ust_cmd
->sock
;
342 cds_list_del(&wait_node
->head
);
344 app
= wait_node
->app
;
347 DBG3("UST app notify socket %d is set", ust_cmd
->sock
);
353 * With no application at this stage the received socket is
354 * basically useless so close it before we free the cmd data
355 * structure for good.
358 ret
= close(ust_cmd
->sock
);
360 PERROR("close ust sock dispatch %d", ust_cmd
->sock
);
362 lttng_fd_put(LTTNG_FD_APPS
, 1);
372 * Lock the global session list so from the register up to the
373 * registration done message, no thread can see the application
374 * and change its state.
380 * Add application to the global hash table. This needs to be
381 * done before the update to the UST registry can locate the
386 /* Set app version. This call will print an error if needed. */
387 (void) ust_app_version(app
);
389 /* Send notify socket through the notify pipe. */
390 ret
= send_socket_to_thread(
391 notifiers
->apps_cmd_notify_pipe_write_fd
,
395 session_unlock_list();
397 * No notify thread, stop the UST tracing. However, this is
398 * not an internal error of the this thread thus setting
399 * the health error code to a normal exit.
406 * Update newly registered application with the tracing
407 * registry info already enabled information.
409 update_ust_app(app
->sock
);
412 * Don't care about return value. Let the manage apps threads
413 * handle app unregistration upon socket close.
415 (void) ust_app_register_done(app
);
418 * Even if the application socket has been closed, send the app
419 * to the thread and unregistration will take place at that
422 ret
= send_socket_to_thread(
423 notifiers
->apps_cmd_pipe_write_fd
,
427 session_unlock_list();
429 * No apps. thread, stop the UST tracing. However, this is
430 * not an internal error of the this thread thus setting
431 * the health error code to a normal exit.
438 session_unlock_list();
440 } while (node
!= NULL
);
443 /* Futex wait on queue. Blocking call on futex() */
444 futex_nto1_wait(¬ifiers
->ust_cmd_queue
->futex
);
447 /* Normal exit, no error */
451 /* Clean up wait queue. */
452 cds_list_for_each_entry_safe(wait_node
, tmp_wait_node
,
453 &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(
463 ¬ifiers
->ust_cmd_queue
->head
,
464 ¬ifiers
->ust_cmd_queue
->tail
);
468 ust_cmd
= caa_container_of(node
, struct ust_command
, node
);
469 ret
= close(ust_cmd
->sock
);
471 PERROR("close ust sock exit dispatch %d", ust_cmd
->sock
);
473 lttng_fd_put(LTTNG_FD_APPS
, 1);
478 DBG("Dispatch thread dying");
481 ERR("Health error occurred in %s", __func__
);
483 health_unregister(health_sessiond
);
484 rcu_unregister_thread();
488 static bool shutdown_ust_dispatch_thread(void *data
)
490 struct thread_notifiers
*notifiers
= data
;
492 CMM_STORE_SHARED(notifiers
->dispatch_thread_exit
, 1);
493 futex_nto1_wake(¬ifiers
->ust_cmd_queue
->futex
);
497 bool launch_ust_dispatch_thread(struct ust_cmd_queue
*cmd_queue
,
498 int apps_cmd_pipe_write_fd
,
499 int apps_cmd_notify_pipe_write_fd
)
501 struct lttng_thread
*thread
;
502 struct thread_notifiers
*notifiers
;
504 notifiers
= zmalloc(sizeof(*notifiers
));
508 notifiers
->ust_cmd_queue
= cmd_queue
;
509 notifiers
->apps_cmd_pipe_write_fd
= apps_cmd_pipe_write_fd
;
510 notifiers
->apps_cmd_notify_pipe_write_fd
= apps_cmd_notify_pipe_write_fd
;
512 thread
= lttng_thread_create("UST registration dispatch",
513 thread_dispatch_ust_registration
,
514 shutdown_ust_dispatch_thread
,
515 cleanup_ust_dispatch_thread
,
520 lttng_thread_put(thread
);