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
||
55 !sess
->ust_session
->active
) {
60 assert(app_sock
>= 0);
61 app
= ust_app_find_by_sock(app_sock
);
64 * Application can be unregistered before so
65 * this is possible hence simply stopping the
68 DBG3("UST app update failed to find app sock %d",
72 ust_app_global_update(sess
->ust_session
, app
);
82 * Sanitize the wait queue of the dispatch registration thread meaning removing
83 * invalid nodes from it. This is to avoid memory leaks for the case the UST
84 * notify socket is never received.
86 static void sanitize_wait_queue(struct ust_reg_wait_queue
*wait_queue
)
88 int ret
, nb_fd
= 0, i
;
89 unsigned int fd_added
= 0;
90 struct lttng_poll_event events
;
91 struct ust_reg_wait_node
*wait_node
= NULL
, *tmp_wait_node
;
95 lttng_poll_init(&events
);
97 /* Just skip everything for an empty queue. */
98 if (!wait_queue
->count
) {
102 ret
= lttng_poll_create(&events
, wait_queue
->count
, LTTNG_CLOEXEC
);
107 cds_list_for_each_entry_safe(wait_node
, tmp_wait_node
,
108 &wait_queue
->head
, head
) {
109 assert(wait_node
->app
);
110 ret
= lttng_poll_add(&events
, wait_node
->app
->sock
,
111 LPOLLHUP
| LPOLLERR
);
124 * Poll but don't block so we can quickly identify the faulty events and
125 * clean them afterwards from the wait queue.
127 ret
= lttng_poll_wait(&events
, 0);
133 for (i
= 0; i
< nb_fd
; i
++) {
135 uint32_t revents
= LTTNG_POLL_GETEV(&events
, i
);
136 int pollfd
= LTTNG_POLL_GETFD(&events
, i
);
138 cds_list_for_each_entry_safe(wait_node
, tmp_wait_node
,
139 &wait_queue
->head
, head
) {
140 if (pollfd
== wait_node
->app
->sock
&&
141 (revents
& (LPOLLHUP
| LPOLLERR
))) {
142 cds_list_del(&wait_node
->head
);
144 ust_app_destroy(wait_node
->app
);
147 * Silence warning of use-after-free in
148 * cds_list_for_each_entry_safe which uses
149 * __typeof__(*wait_node).
154 ERR("Unexpected poll events %u for sock %d", revents
, pollfd
);
161 DBG("Wait queue sanitized, %d node were cleaned up", nb_fd
);
165 lttng_poll_clean(&events
);
169 lttng_poll_clean(&events
);
171 ERR("Unable to sanitize wait queue");
176 * Send a socket to a thread This is called from the dispatch UST registration
177 * thread once all sockets are set for the application.
179 * The sock value can be invalid, we don't really care, the thread will handle
180 * it and make the necessary cleanup if so.
182 * On success, return 0 else a negative value being the errno message of the
185 static int send_socket_to_thread(int fd
, int sock
)
190 * It's possible that the FD is set as invalid with -1 concurrently just
191 * before calling this function being a shutdown state of the thread.
198 ret
= lttng_write(fd
, &sock
, sizeof(sock
));
199 if (ret
< sizeof(sock
)) {
200 PERROR("write apps pipe %d", fd
);
207 /* All good. Don't send back the write positive ret value. */
213 static void cleanup_ust_dispatch_thread(void *data
)
219 * Dispatch request from the registration threads to the application
220 * communication thread.
222 static void *thread_dispatch_ust_registration(void *data
)
225 struct cds_wfcq_node
*node
;
226 struct ust_command
*ust_cmd
= NULL
;
227 struct ust_reg_wait_node
*wait_node
= NULL
, *tmp_wait_node
;
228 struct ust_reg_wait_queue wait_queue
= {
231 struct thread_notifiers
*notifiers
= data
;
233 rcu_register_thread();
235 health_register(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
= NULL
;
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(
271 ¬ifiers
->ust_cmd_queue
->head
,
272 ¬ifiers
->ust_cmd_queue
->tail
);
274 DBG("Woken up but nothing in the UST command queue");
275 /* Continue thread execution */
279 ust_cmd
= caa_container_of(node
, struct ust_command
, node
);
281 DBG("Dispatching UST registration pid:%d ppid:%d uid:%d"
282 " gid:%d sock:%d name:%s (version %d.%d)",
283 ust_cmd
->reg_msg
.pid
, ust_cmd
->reg_msg
.ppid
,
284 ust_cmd
->reg_msg
.uid
, ust_cmd
->reg_msg
.gid
,
285 ust_cmd
->sock
, ust_cmd
->reg_msg
.name
,
286 ust_cmd
->reg_msg
.major
, ust_cmd
->reg_msg
.minor
);
288 if (ust_cmd
->reg_msg
.type
== USTCTL_SOCKET_CMD
) {
289 wait_node
= zmalloc(sizeof(*wait_node
));
291 PERROR("zmalloc wait_node dispatch");
292 ret
= close(ust_cmd
->sock
);
294 PERROR("close ust sock dispatch %d", ust_cmd
->sock
);
296 lttng_fd_put(LTTNG_FD_APPS
, 1);
301 CDS_INIT_LIST_HEAD(&wait_node
->head
);
303 /* Create application object if socket is CMD. */
304 wait_node
->app
= ust_app_create(&ust_cmd
->reg_msg
,
306 if (!wait_node
->app
) {
307 ret
= close(ust_cmd
->sock
);
309 PERROR("close ust sock dispatch %d", ust_cmd
->sock
);
311 lttng_fd_put(LTTNG_FD_APPS
, 1);
319 * Add application to the wait queue so we can set the notify
320 * socket before putting this object in the global ht.
322 cds_list_add(&wait_node
->head
, &wait_queue
.head
);
328 * We have to continue here since we don't have the notify
329 * socket and the application MUST be added to the hash table
330 * only at that moment.
335 * Look for the application in the local wait queue and set the
336 * notify socket if found.
338 cds_list_for_each_entry_safe(wait_node
, tmp_wait_node
,
339 &wait_queue
.head
, head
) {
340 health_code_update();
341 if (wait_node
->app
->pid
== ust_cmd
->reg_msg
.pid
) {
342 wait_node
->app
->notify_sock
= ust_cmd
->sock
;
343 cds_list_del(&wait_node
->head
);
345 app
= wait_node
->app
;
348 DBG3("UST app notify socket %d is set", ust_cmd
->sock
);
354 * With no application at this stage the received socket is
355 * basically useless so close it before we free the cmd data
356 * structure for good.
359 ret
= close(ust_cmd
->sock
);
361 PERROR("close ust sock dispatch %d", ust_cmd
->sock
);
363 lttng_fd_put(LTTNG_FD_APPS
, 1);
373 * Lock the global session list so from the register up to the
374 * registration done message, no thread can see the application
375 * and change its state.
381 * Add application to the global hash table. This needs to be
382 * done before the update to the UST registry can locate the
387 /* Set app version. This call will print an error if needed. */
388 (void) ust_app_version(app
);
390 /* Send notify socket through the notify pipe. */
391 ret
= send_socket_to_thread(
392 notifiers
->apps_cmd_notify_pipe_write_fd
,
396 session_unlock_list();
398 * No notify thread, stop the UST tracing. However, this is
399 * not an internal error of the this thread thus setting
400 * the health error code to a normal exit.
407 * Update newly registered application with the tracing
408 * registry info already enabled information.
410 update_ust_app(app
->sock
);
413 * Don't care about return value. Let the manage apps threads
414 * handle app unregistration upon socket close.
416 (void) ust_app_register_done(app
);
419 * Even if the application socket has been closed, send the app
420 * to the thread and unregistration will take place at that
423 ret
= send_socket_to_thread(
424 notifiers
->apps_cmd_pipe_write_fd
,
428 session_unlock_list();
430 * No apps. thread, stop the UST tracing. However, this is
431 * not an internal error of the this thread thus setting
432 * the health error code to a normal exit.
439 session_unlock_list();
441 } while (node
!= NULL
);
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
,
454 &wait_queue
.head
, head
) {
455 cds_list_del(&wait_node
->head
);
460 /* Empty command queue. */
462 /* Dequeue command for registration */
463 node
= cds_wfcq_dequeue_blocking(
464 ¬ifiers
->ust_cmd_queue
->head
,
465 ¬ifiers
->ust_cmd_queue
->tail
);
469 ust_cmd
= caa_container_of(node
, struct ust_command
, node
);
470 ret
= close(ust_cmd
->sock
);
472 PERROR("close ust sock exit dispatch %d", ust_cmd
->sock
);
474 lttng_fd_put(LTTNG_FD_APPS
, 1);
479 DBG("Dispatch thread dying");
482 ERR("Health error occurred in %s", __func__
);
484 health_unregister(health_sessiond
);
485 rcu_unregister_thread();
489 static bool shutdown_ust_dispatch_thread(void *data
)
491 struct thread_notifiers
*notifiers
= data
;
493 CMM_STORE_SHARED(notifiers
->dispatch_thread_exit
, 1);
494 futex_nto1_wake(¬ifiers
->ust_cmd_queue
->futex
);
498 bool launch_ust_dispatch_thread(struct ust_cmd_queue
*cmd_queue
,
499 int apps_cmd_pipe_write_fd
,
500 int apps_cmd_notify_pipe_write_fd
)
502 struct lttng_thread
*thread
;
503 struct thread_notifiers
*notifiers
;
505 notifiers
= zmalloc(sizeof(*notifiers
));
509 notifiers
->ust_cmd_queue
= cmd_queue
;
510 notifiers
->apps_cmd_pipe_write_fd
= apps_cmd_pipe_write_fd
;
511 notifiers
->apps_cmd_notify_pipe_write_fd
= apps_cmd_notify_pipe_write_fd
;
513 thread
= lttng_thread_create("UST registration dispatch",
514 thread_dispatch_ust_registration
,
515 shutdown_ust_dispatch_thread
,
516 cleanup_ust_dispatch_thread
,
521 lttng_thread_put(thread
);