4 * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
5 * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; only
10 * version 2.1 of the License.
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with this library; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 #include <sys/types.h>
25 #include <sys/socket.h>
28 #include <sys/types.h>
35 #include <semaphore.h>
40 #include <urcu/uatomic.h>
41 #include <urcu/futex.h>
42 #include <urcu/compiler.h>
44 #include <lttng/ust-events.h>
45 #include <lttng/ust-abi.h>
46 #include <lttng/ust.h>
47 #include <lttng/ust-error.h>
48 #include <lttng/ust-ctl.h>
49 #include <urcu/tls-compat.h>
52 #include <usterr-signal-safe.h>
54 #include "tracepoint-internal.h"
55 #include "lttng-tracer-core.h"
57 #include "../libringbuffer/rb-init.h"
58 #include "lttng-ust-statedump.h"
60 #include "../libringbuffer/getcpu.h"
63 /* Concatenate lttng ust shared library name with its major version number. */
64 #define LTTNG_UST_LIB_SO_NAME "liblttng-ust.so." LTTNG_UST_LIBRARY_VERSION_MAJOR
67 * Has lttng ust comm constructor been called ?
69 static int initialized
;
72 * The ust_lock/ust_unlock lock is used as a communication thread mutex.
73 * Held when handling a command, also held by fork() to deal with
74 * removal of threads, and by exit path.
76 * The UST lock is the centralized mutex across UST tracing control and
79 * ust_exit_mutex must never nest in ust_mutex.
81 * ust_fork_mutex must never nest in ust_mutex.
83 * ust_mutex_nest is a per-thread nesting counter, allowing the perf
84 * counter lazy initialization called by events within the statedump,
85 * which traces while the ust_mutex is held.
87 * ust_lock nests within the dynamic loader lock (within glibc) because
88 * it is taken within the library constructor.
90 static pthread_mutex_t ust_mutex
= PTHREAD_MUTEX_INITIALIZER
;
92 /* Allow nesting the ust_mutex within the same thread. */
93 static DEFINE_URCU_TLS(int, ust_mutex_nest
);
96 * ust_exit_mutex protects thread_active variable wrt thread exit. It
97 * cannot be done by ust_mutex because pthread_cancel(), which takes an
98 * internal libc lock, cannot nest within ust_mutex.
100 * It never nests within a ust_mutex.
102 static pthread_mutex_t ust_exit_mutex
= PTHREAD_MUTEX_INITIALIZER
;
105 * ust_fork_mutex protects base address statedump tracing against forks. It
106 * prevents the dynamic loader lock to be taken (by base address statedump
107 * tracing) while a fork is happening, thus preventing deadlock issues with
108 * the dynamic loader lock.
110 static pthread_mutex_t ust_fork_mutex
= PTHREAD_MUTEX_INITIALIZER
;
112 /* Should the ust comm thread quit ? */
113 static int lttng_ust_comm_should_quit
;
116 * This variable can be tested by applications to check whether
117 * lttng-ust is loaded. They simply have to define their own
118 * "lttng_ust_loaded" weak symbol, and test it. It is set to 1 by the
119 * library constructor.
121 int lttng_ust_loaded
__attribute__((weak
));
124 * Return 0 on success, -1 if should quit.
125 * The lock is taken in both cases.
130 sigset_t sig_all_blocked
, orig_mask
;
133 ret
= pthread_setcancelstate(PTHREAD_CANCEL_DISABLE
, &oldstate
);
135 ERR("pthread_setcancelstate: %s", strerror(ret
));
137 if (oldstate
!= PTHREAD_CANCEL_ENABLE
) {
138 ERR("pthread_setcancelstate: unexpected oldstate");
140 sigfillset(&sig_all_blocked
);
141 ret
= pthread_sigmask(SIG_SETMASK
, &sig_all_blocked
, &orig_mask
);
143 ERR("pthread_sigmask: %s", strerror(ret
));
145 if (!URCU_TLS(ust_mutex_nest
)++)
146 pthread_mutex_lock(&ust_mutex
);
147 ret
= pthread_sigmask(SIG_SETMASK
, &orig_mask
, NULL
);
149 ERR("pthread_sigmask: %s", strerror(ret
));
151 if (lttng_ust_comm_should_quit
) {
159 * ust_lock_nocheck() can be used in constructors/destructors, because
160 * they are already nested within the dynamic loader lock, and therefore
161 * have exclusive access against execution of liblttng-ust destructor.
164 void ust_lock_nocheck(void)
166 sigset_t sig_all_blocked
, orig_mask
;
169 ret
= pthread_setcancelstate(PTHREAD_CANCEL_DISABLE
, &oldstate
);
171 ERR("pthread_setcancelstate: %s", strerror(ret
));
173 if (oldstate
!= PTHREAD_CANCEL_ENABLE
) {
174 ERR("pthread_setcancelstate: unexpected oldstate");
176 sigfillset(&sig_all_blocked
);
177 ret
= pthread_sigmask(SIG_SETMASK
, &sig_all_blocked
, &orig_mask
);
179 ERR("pthread_sigmask: %s", strerror(ret
));
181 if (!URCU_TLS(ust_mutex_nest
)++)
182 pthread_mutex_lock(&ust_mutex
);
183 ret
= pthread_sigmask(SIG_SETMASK
, &orig_mask
, NULL
);
185 ERR("pthread_sigmask: %s", strerror(ret
));
192 void ust_unlock(void)
194 sigset_t sig_all_blocked
, orig_mask
;
197 sigfillset(&sig_all_blocked
);
198 ret
= pthread_sigmask(SIG_SETMASK
, &sig_all_blocked
, &orig_mask
);
200 ERR("pthread_sigmask: %s", strerror(ret
));
202 if (!--URCU_TLS(ust_mutex_nest
))
203 pthread_mutex_unlock(&ust_mutex
);
204 ret
= pthread_sigmask(SIG_SETMASK
, &orig_mask
, NULL
);
206 ERR("pthread_sigmask: %s", strerror(ret
));
208 ret
= pthread_setcancelstate(PTHREAD_CANCEL_ENABLE
, &oldstate
);
210 ERR("pthread_setcancelstate: %s", strerror(ret
));
212 if (oldstate
!= PTHREAD_CANCEL_DISABLE
) {
213 ERR("pthread_setcancelstate: unexpected oldstate");
218 * Wait for either of these before continuing to the main
220 * - the register_done message from sessiond daemon
221 * (will let the sessiond daemon enable sessions before main
223 * - sessiond daemon is not reachable.
224 * - timeout (ensuring applications are resilient to session
227 static sem_t constructor_wait
;
229 * Doing this for both the global and local sessiond.
232 sem_count_initial_value
= 4,
235 static int sem_count
= sem_count_initial_value
;
238 * Counting nesting within lttng-ust. Used to ensure that calling fork()
239 * from liblttng-ust does not execute the pre/post fork handlers.
241 static DEFINE_URCU_TLS(int, lttng_ust_nest_count
);
244 * Info about socket and associated listener thread.
248 pthread_t ust_listener
; /* listener thread */
250 int registration_done
;
255 char sock_path
[PATH_MAX
];
259 char wait_shm_path
[PATH_MAX
];
261 /* Keep track of lazy state dump not performed yet. */
262 int statedump_pending
;
263 int initial_statedump_done
;
266 /* Socket from app (connect) to session daemon (listen) for communication */
267 struct sock_info global_apps
= {
272 .registration_done
= 0,
276 .sock_path
= LTTNG_DEFAULT_RUNDIR
"/" LTTNG_UST_SOCK_FILENAME
,
280 .wait_shm_path
= "/" LTTNG_UST_WAIT_FILENAME
,
282 .statedump_pending
= 0,
283 .initial_statedump_done
= 0,
286 /* TODO: allow global_apps_sock_path override */
288 struct sock_info local_apps
= {
292 .registration_done
= 0,
293 .allowed
= 0, /* Check setuid bit first */
299 .statedump_pending
= 0,
300 .initial_statedump_done
= 0,
303 static int wait_poll_fallback
;
305 static const char *cmd_name_mapping
[] = {
306 [ LTTNG_UST_RELEASE
] = "Release",
307 [ LTTNG_UST_SESSION
] = "Create Session",
308 [ LTTNG_UST_TRACER_VERSION
] = "Get Tracer Version",
310 [ LTTNG_UST_TRACEPOINT_LIST
] = "Create Tracepoint List",
311 [ LTTNG_UST_WAIT_QUIESCENT
] = "Wait for Quiescent State",
312 [ LTTNG_UST_REGISTER_DONE
] = "Registration Done",
313 [ LTTNG_UST_TRACEPOINT_FIELD_LIST
] = "Create Tracepoint Field List",
315 /* Session FD commands */
316 [ LTTNG_UST_CHANNEL
] = "Create Channel",
317 [ LTTNG_UST_SESSION_START
] = "Start Session",
318 [ LTTNG_UST_SESSION_STOP
] = "Stop Session",
320 /* Channel FD commands */
321 [ LTTNG_UST_STREAM
] = "Create Stream",
322 [ LTTNG_UST_EVENT
] = "Create Event",
324 /* Event and Channel FD commands */
325 [ LTTNG_UST_CONTEXT
] = "Create Context",
326 [ LTTNG_UST_FLUSH_BUFFER
] = "Flush Buffer",
328 /* Event, Channel and Session commands */
329 [ LTTNG_UST_ENABLE
] = "Enable",
330 [ LTTNG_UST_DISABLE
] = "Disable",
332 /* Tracepoint list commands */
333 [ LTTNG_UST_TRACEPOINT_LIST_GET
] = "List Next Tracepoint",
334 [ LTTNG_UST_TRACEPOINT_FIELD_LIST_GET
] = "List Next Tracepoint Field",
336 /* Event FD commands */
337 [ LTTNG_UST_FILTER
] = "Create Filter",
338 [ LTTNG_UST_EXCLUSION
] = "Add exclusions to event",
341 static const char *str_timeout
;
342 static int got_timeout_env
;
344 extern void lttng_ring_buffer_client_overwrite_init(void);
345 extern void lttng_ring_buffer_client_overwrite_rt_init(void);
346 extern void lttng_ring_buffer_client_discard_init(void);
347 extern void lttng_ring_buffer_client_discard_rt_init(void);
348 extern void lttng_ring_buffer_metadata_client_init(void);
349 extern void lttng_ring_buffer_client_overwrite_exit(void);
350 extern void lttng_ring_buffer_client_overwrite_rt_exit(void);
351 extern void lttng_ring_buffer_client_discard_exit(void);
352 extern void lttng_ring_buffer_client_discard_rt_exit(void);
353 extern void lttng_ring_buffer_metadata_client_exit(void);
355 static char *get_map_shm(struct sock_info
*sock_info
);
357 ssize_t
lttng_ust_read(int fd
, void *buf
, size_t len
)
360 size_t copied
= 0, to_copy
= len
;
363 ret
= read(fd
, buf
+ copied
, to_copy
);
368 } while ((ret
> 0 && to_copy
> 0)
369 || (ret
< 0 && errno
== EINTR
));
376 * Returns the HOME directory path. Caller MUST NOT free(3) the returned
380 const char *get_lttng_home_dir(void)
384 val
= (const char *) lttng_getenv("LTTNG_HOME");
388 return (const char *) lttng_getenv("HOME");
392 * Force a read (imply TLS fixup for dlopen) of TLS variables.
395 void lttng_fixup_nest_count_tls(void)
397 asm volatile ("" : : "m" (URCU_TLS(lttng_ust_nest_count
)));
401 void lttng_fixup_ust_mutex_nest_tls(void)
403 asm volatile ("" : : "m" (URCU_TLS(ust_mutex_nest
)));
410 void lttng_fixup_urcu_bp_tls(void)
416 void lttng_ust_fixup_tls(void)
418 lttng_fixup_urcu_bp_tls();
419 lttng_fixup_ringbuffer_tls();
420 lttng_fixup_vtid_tls();
421 lttng_fixup_nest_count_tls();
422 lttng_fixup_procname_tls();
423 lttng_fixup_ust_mutex_nest_tls();
424 lttng_ust_fixup_fd_tracker_tls();
427 int lttng_get_notify_socket(void *owner
)
429 struct sock_info
*info
= owner
;
431 return info
->notify_socket
;
435 void print_cmd(int cmd
, int handle
)
437 const char *cmd_name
= "Unknown";
439 if (cmd
>= 0 && cmd
< LTTNG_ARRAY_SIZE(cmd_name_mapping
)
440 && cmd_name_mapping
[cmd
]) {
441 cmd_name
= cmd_name_mapping
[cmd
];
443 DBG("Message Received \"%s\" (%d), Handle \"%s\" (%d)",
445 lttng_ust_obj_get_name(handle
), handle
);
449 int setup_global_apps(void)
452 assert(!global_apps
.wait_shm_mmap
);
454 global_apps
.wait_shm_mmap
= get_map_shm(&global_apps
);
455 if (!global_apps
.wait_shm_mmap
) {
456 WARN("Unable to get map shm for global apps. Disabling LTTng-UST global tracing.");
457 global_apps
.allowed
= 0;
462 global_apps
.allowed
= 1;
467 int setup_local_apps(void)
470 const char *home_dir
;
473 assert(!local_apps
.wait_shm_mmap
);
477 * Disallow per-user tracing for setuid binaries.
479 if (uid
!= geteuid()) {
480 assert(local_apps
.allowed
== 0);
484 home_dir
= get_lttng_home_dir();
486 WARN("HOME environment variable not set. Disabling LTTng-UST per-user tracing.");
487 assert(local_apps
.allowed
== 0);
491 local_apps
.allowed
= 1;
492 snprintf(local_apps
.sock_path
, PATH_MAX
, "%s/%s/%s",
494 LTTNG_DEFAULT_HOME_RUNDIR
,
495 LTTNG_UST_SOCK_FILENAME
);
496 snprintf(local_apps
.wait_shm_path
, PATH_MAX
, "/%s-%u",
497 LTTNG_UST_WAIT_FILENAME
,
500 local_apps
.wait_shm_mmap
= get_map_shm(&local_apps
);
501 if (!local_apps
.wait_shm_mmap
) {
502 WARN("Unable to get map shm for local apps. Disabling LTTng-UST per-user tracing.");
503 local_apps
.allowed
= 0;
512 * Get socket timeout, in ms.
513 * -1: wait forever. 0: don't wait. >0: timeout, in ms.
516 long get_timeout(void)
518 long constructor_delay_ms
= LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS
;
520 if (!got_timeout_env
) {
521 str_timeout
= lttng_getenv("LTTNG_UST_REGISTER_TIMEOUT");
525 constructor_delay_ms
= strtol(str_timeout
, NULL
, 10);
526 /* All negative values are considered as "-1". */
527 if (constructor_delay_ms
< -1)
528 constructor_delay_ms
= -1;
529 return constructor_delay_ms
;
532 /* Timeout for notify socket send and recv. */
534 long get_notify_sock_timeout(void)
536 return get_timeout();
539 /* Timeout for connecting to cmd and notify sockets. */
541 long get_connect_sock_timeout(void)
543 return get_timeout();
547 * Return values: -1: wait forever. 0: don't wait. 1: timeout wait.
550 int get_constructor_timeout(struct timespec
*constructor_timeout
)
552 long constructor_delay_ms
;
555 constructor_delay_ms
= get_timeout();
557 switch (constructor_delay_ms
) {
558 case -1:/* fall-through */
560 return constructor_delay_ms
;
566 * If we are unable to find the current time, don't wait.
568 ret
= clock_gettime(CLOCK_REALTIME
, constructor_timeout
);
573 constructor_timeout
->tv_sec
+= constructor_delay_ms
/ 1000UL;
574 constructor_timeout
->tv_nsec
+=
575 (constructor_delay_ms
% 1000UL) * 1000000UL;
576 if (constructor_timeout
->tv_nsec
>= 1000000000UL) {
577 constructor_timeout
->tv_sec
++;
578 constructor_timeout
->tv_nsec
-= 1000000000UL;
580 /* Timeout wait (constructor_delay_ms). */
585 void get_allow_blocking(void)
587 const char *str_allow_blocking
=
588 lttng_getenv("LTTNG_UST_ALLOW_BLOCKING");
590 if (str_allow_blocking
) {
591 DBG("%s environment variable is set",
592 "LTTNG_UST_ALLOW_BLOCKING");
593 lttng_ust_ringbuffer_set_allow_blocking();
598 int register_to_sessiond(int socket
, enum ustctl_socket_type type
)
600 return ustcomm_send_reg_msg(socket
,
603 lttng_alignof(uint8_t) * CHAR_BIT
,
604 lttng_alignof(uint16_t) * CHAR_BIT
,
605 lttng_alignof(uint32_t) * CHAR_BIT
,
606 lttng_alignof(uint64_t) * CHAR_BIT
,
607 lttng_alignof(unsigned long) * CHAR_BIT
);
611 int send_reply(int sock
, struct ustcomm_ust_reply
*lur
)
615 len
= ustcomm_send_unix_sock(sock
, lur
, sizeof(*lur
));
618 DBG("message successfully sent");
621 if (len
== -ECONNRESET
) {
622 DBG("remote end closed connection");
627 DBG("incorrect message size: %zd", len
);
633 void decrement_sem_count(unsigned int count
)
637 assert(uatomic_read(&sem_count
) >= count
);
639 if (uatomic_read(&sem_count
) <= 0) {
643 ret
= uatomic_add_return(&sem_count
, -count
);
645 ret
= sem_post(&constructor_wait
);
651 int handle_register_done(struct sock_info
*sock_info
)
653 if (sock_info
->registration_done
)
655 sock_info
->registration_done
= 1;
657 decrement_sem_count(1);
663 int handle_register_failed(struct sock_info
*sock_info
)
665 if (sock_info
->registration_done
)
667 sock_info
->registration_done
= 1;
668 sock_info
->initial_statedump_done
= 1;
670 decrement_sem_count(2);
676 * Only execute pending statedump after the constructor semaphore has
677 * been posted by the current listener thread. This means statedump will
678 * only be performed after the "registration done" command is received
679 * from this thread's session daemon.
681 * This ensures we don't run into deadlock issues with the dynamic
682 * loader mutex, which is held while the constructor is called and
683 * waiting on the constructor semaphore. All operations requiring this
684 * dynamic loader lock need to be postponed using this mechanism.
686 * In a scenario with two session daemons connected to the application,
687 * it is possible that the first listener thread which receives the
688 * registration done command issues its statedump while the dynamic
689 * loader lock is still held by the application constructor waiting on
690 * the semaphore. It will however be allowed to proceed when the
691 * second session daemon sends the registration done command to the
692 * second listener thread. This situation therefore does not produce
696 void handle_pending_statedump(struct sock_info
*sock_info
)
698 if (sock_info
->registration_done
&& sock_info
->statedump_pending
) {
699 sock_info
->statedump_pending
= 0;
700 pthread_mutex_lock(&ust_fork_mutex
);
701 lttng_handle_pending_statedump(sock_info
);
702 pthread_mutex_unlock(&ust_fork_mutex
);
704 if (!sock_info
->initial_statedump_done
) {
705 sock_info
->initial_statedump_done
= 1;
706 decrement_sem_count(1);
712 int handle_message(struct sock_info
*sock_info
,
713 int sock
, struct ustcomm_ust_msg
*lum
)
716 const struct lttng_ust_objd_ops
*ops
;
717 struct ustcomm_ust_reply lur
;
719 char ctxstr
[LTTNG_UST_SYM_NAME_LEN
]; /* App context string. */
722 memset(&lur
, 0, sizeof(lur
));
725 ret
= -LTTNG_UST_ERR_EXITING
;
729 ops
= objd_ops(lum
->handle
);
736 case LTTNG_UST_REGISTER_DONE
:
737 if (lum
->handle
== LTTNG_UST_ROOT_HANDLE
)
738 ret
= handle_register_done(sock_info
);
742 case LTTNG_UST_RELEASE
:
743 if (lum
->handle
== LTTNG_UST_ROOT_HANDLE
)
746 ret
= lttng_ust_objd_unref(lum
->handle
, 1);
748 case LTTNG_UST_FILTER
:
750 /* Receive filter data */
751 struct lttng_ust_filter_bytecode_node
*bytecode
;
753 if (lum
->u
.filter
.data_size
> FILTER_BYTECODE_MAX_LEN
) {
754 ERR("Filter data size is too large: %u bytes",
755 lum
->u
.filter
.data_size
);
760 if (lum
->u
.filter
.reloc_offset
> lum
->u
.filter
.data_size
) {
761 ERR("Filter reloc offset %u is not within data",
762 lum
->u
.filter
.reloc_offset
);
767 bytecode
= zmalloc(sizeof(*bytecode
) + lum
->u
.filter
.data_size
);
772 len
= ustcomm_recv_unix_sock(sock
, bytecode
->bc
.data
,
773 lum
->u
.filter
.data_size
);
775 case 0: /* orderly shutdown */
780 if (len
== lum
->u
.filter
.data_size
) {
781 DBG("filter data received");
783 } else if (len
< 0) {
784 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len
);
785 if (len
== -ECONNRESET
) {
786 ERR("%s remote end closed connection", sock_info
->name
);
795 DBG("incorrect filter data message size: %zd", len
);
801 bytecode
->bc
.len
= lum
->u
.filter
.data_size
;
802 bytecode
->bc
.reloc_offset
= lum
->u
.filter
.reloc_offset
;
803 bytecode
->bc
.seqnum
= lum
->u
.filter
.seqnum
;
805 ret
= ops
->cmd(lum
->handle
, lum
->cmd
,
806 (unsigned long) bytecode
,
811 /* don't free bytecode if everything went fine. */
818 case LTTNG_UST_EXCLUSION
:
820 /* Receive exclusion names */
821 struct lttng_ust_excluder_node
*node
;
824 count
= lum
->u
.exclusion
.count
;
826 /* There are no names to read */
830 node
= zmalloc(sizeof(*node
) +
831 count
* LTTNG_UST_SYM_NAME_LEN
);
836 node
->excluder
.count
= count
;
837 len
= ustcomm_recv_unix_sock(sock
, node
->excluder
.names
,
838 count
* LTTNG_UST_SYM_NAME_LEN
);
840 case 0: /* orderly shutdown */
845 if (len
== count
* LTTNG_UST_SYM_NAME_LEN
) {
846 DBG("Exclusion data received");
848 } else if (len
< 0) {
849 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len
);
850 if (len
== -ECONNRESET
) {
851 ERR("%s remote end closed connection", sock_info
->name
);
860 DBG("Incorrect exclusion data message size: %zd", len
);
867 ret
= ops
->cmd(lum
->handle
, lum
->cmd
,
868 (unsigned long) node
,
873 /* Don't free exclusion data if everything went fine. */
880 case LTTNG_UST_CHANNEL
:
885 len
= ustcomm_recv_channel_from_sessiond(sock
,
886 &chan_data
, lum
->u
.channel
.len
,
889 case 0: /* orderly shutdown */
893 if (len
== lum
->u
.channel
.len
) {
894 DBG("channel data received");
896 } else if (len
< 0) {
897 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len
);
898 if (len
== -ECONNRESET
) {
899 ERR("%s remote end closed connection", sock_info
->name
);
906 DBG("incorrect channel data message size: %zd", len
);
911 args
.channel
.chan_data
= chan_data
;
912 args
.channel
.wakeup_fd
= wakeup_fd
;
914 ret
= ops
->cmd(lum
->handle
, lum
->cmd
,
915 (unsigned long) &lum
->u
,
921 case LTTNG_UST_STREAM
:
923 /* Receive shm_fd, wakeup_fd */
924 ret
= ustcomm_recv_stream_from_sessiond(sock
,
927 &args
.stream
.wakeup_fd
);
933 ret
= ops
->cmd(lum
->handle
, lum
->cmd
,
934 (unsigned long) &lum
->u
,
940 case LTTNG_UST_CONTEXT
:
941 switch (lum
->u
.context
.ctx
) {
942 case LTTNG_UST_CONTEXT_APP_CONTEXT
:
945 size_t ctxlen
, recvlen
;
947 ctxlen
= strlen("$app.") + lum
->u
.context
.u
.app_ctx
.provider_name_len
- 1
948 + strlen(":") + lum
->u
.context
.u
.app_ctx
.ctx_name_len
;
949 if (ctxlen
>= LTTNG_UST_SYM_NAME_LEN
) {
950 ERR("Application context string length size is too large: %zu bytes",
955 strcpy(ctxstr
, "$app.");
956 p
= &ctxstr
[strlen("$app.")];
957 recvlen
= ctxlen
- strlen("$app.");
958 len
= ustcomm_recv_unix_sock(sock
, p
, recvlen
);
960 case 0: /* orderly shutdown */
964 if (len
== recvlen
) {
965 DBG("app context data received");
967 } else if (len
< 0) {
968 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len
);
969 if (len
== -ECONNRESET
) {
970 ERR("%s remote end closed connection", sock_info
->name
);
977 DBG("incorrect app context data message size: %zd", len
);
982 /* Put : between provider and ctxname. */
983 p
[lum
->u
.context
.u
.app_ctx
.provider_name_len
- 1] = ':';
984 args
.app_context
.ctxname
= ctxstr
;
991 ret
= ops
->cmd(lum
->handle
, lum
->cmd
,
992 (unsigned long) &lum
->u
,
1000 ret
= ops
->cmd(lum
->handle
, lum
->cmd
,
1001 (unsigned long) &lum
->u
,
1008 lur
.handle
= lum
->handle
;
1012 lur
.ret_code
= LTTNG_UST_OK
;
1015 * Use -LTTNG_UST_ERR as wildcard for UST internal
1016 * error that are not caused by the transport, except if
1017 * we already have a more precise error message to
1020 if (ret
> -LTTNG_UST_ERR
) {
1021 /* Translate code to UST error. */
1024 lur
.ret_code
= -LTTNG_UST_ERR_EXIST
;
1027 lur
.ret_code
= -LTTNG_UST_ERR_INVAL
;
1030 lur
.ret_code
= -LTTNG_UST_ERR_NOENT
;
1033 lur
.ret_code
= -LTTNG_UST_ERR_PERM
;
1036 lur
.ret_code
= -LTTNG_UST_ERR_NOSYS
;
1039 lur
.ret_code
= -LTTNG_UST_ERR
;
1048 case LTTNG_UST_TRACER_VERSION
:
1049 lur
.u
.version
= lum
->u
.version
;
1051 case LTTNG_UST_TRACEPOINT_LIST_GET
:
1052 memcpy(&lur
.u
.tracepoint
, &lum
->u
.tracepoint
, sizeof(lur
.u
.tracepoint
));
1056 DBG("Return value: %d", lur
.ret_val
);
1061 * Performed delayed statedump operations outside of the UST
1062 * lock. We need to take the dynamic loader lock before we take
1063 * the UST lock internally within handle_pending_statedump().
1065 handle_pending_statedump(sock_info
);
1068 ret
= -LTTNG_UST_ERR_EXITING
;
1072 ret
= send_reply(sock
, &lur
);
1074 DBG("error sending reply");
1079 * LTTNG_UST_TRACEPOINT_FIELD_LIST_GET needs to send the field
1082 if (lur
.ret_code
== LTTNG_UST_OK
) {
1084 case LTTNG_UST_TRACEPOINT_FIELD_LIST_GET
:
1085 len
= ustcomm_send_unix_sock(sock
,
1086 &args
.field_list
.entry
,
1087 sizeof(args
.field_list
.entry
));
1092 if (len
!= sizeof(args
.field_list
.entry
)) {
1106 void cleanup_sock_info(struct sock_info
*sock_info
, int exiting
)
1110 if (sock_info
->root_handle
!= -1) {
1111 ret
= lttng_ust_objd_unref(sock_info
->root_handle
, 1);
1113 ERR("Error unref root handle");
1115 sock_info
->root_handle
= -1;
1117 sock_info
->registration_done
= 0;
1118 sock_info
->initial_statedump_done
= 0;
1121 * wait_shm_mmap, socket and notify socket are used by listener
1122 * threads outside of the ust lock, so we cannot tear them down
1123 * ourselves, because we cannot join on these threads. Leave
1124 * responsibility of cleaning up these resources to the OS
1130 if (sock_info
->socket
!= -1) {
1131 ret
= ustcomm_close_unix_sock(sock_info
->socket
);
1133 ERR("Error closing ust cmd socket");
1135 sock_info
->socket
= -1;
1137 if (sock_info
->notify_socket
!= -1) {
1138 ret
= ustcomm_close_unix_sock(sock_info
->notify_socket
);
1140 ERR("Error closing ust notify socket");
1142 sock_info
->notify_socket
= -1;
1144 if (sock_info
->wait_shm_mmap
) {
1147 page_size
= sysconf(_SC_PAGE_SIZE
);
1148 if (page_size
<= 0) {
1152 PERROR("Error in sysconf(_SC_PAGE_SIZE)");
1154 ret
= munmap(sock_info
->wait_shm_mmap
, page_size
);
1156 ERR("Error unmapping wait shm");
1159 sock_info
->wait_shm_mmap
= NULL
;
1164 * Using fork to set umask in the child process (not multi-thread safe).
1165 * We deal with the shm_open vs ftruncate race (happening when the
1166 * sessiond owns the shm and does not let everybody modify it, to ensure
1167 * safety against shm_unlink) by simply letting the mmap fail and
1168 * retrying after a few seconds.
1169 * For global shm, everybody has rw access to it until the sessiond
1173 int get_wait_shm(struct sock_info
*sock_info
, size_t mmap_size
)
1175 int wait_shm_fd
, ret
;
1179 * Try to open read-only.
1181 wait_shm_fd
= shm_open(sock_info
->wait_shm_path
, O_RDONLY
, 0);
1182 if (wait_shm_fd
>= 0) {
1185 size_t bytes_read
= 0;
1188 * Try to read the fd. If unable to do so, try opening
1192 len
= read(wait_shm_fd
,
1193 &((char *) &tmp_read
)[bytes_read
],
1194 sizeof(tmp_read
) - bytes_read
);
1198 } while ((len
< 0 && errno
== EINTR
)
1199 || (len
> 0 && bytes_read
< sizeof(tmp_read
)));
1200 if (bytes_read
!= sizeof(tmp_read
)) {
1201 ret
= close(wait_shm_fd
);
1203 ERR("close wait_shm_fd");
1208 } else if (wait_shm_fd
< 0 && errno
!= ENOENT
) {
1210 * Real-only open did not work, and it's not because the
1211 * entry was not present. It's a failure that prohibits
1214 ERR("Error opening shm %s", sock_info
->wait_shm_path
);
1220 * If the open failed because the file did not exist, or because
1221 * the file was not truncated yet, try creating it ourself.
1223 URCU_TLS(lttng_ust_nest_count
)++;
1225 URCU_TLS(lttng_ust_nest_count
)--;
1230 * Parent: wait for child to return, in which case the
1231 * shared memory map will have been created.
1233 pid
= wait(&status
);
1234 if (pid
< 0 || !WIFEXITED(status
) || WEXITSTATUS(status
) != 0) {
1239 * Try to open read-only again after creation.
1241 wait_shm_fd
= shm_open(sock_info
->wait_shm_path
, O_RDONLY
, 0);
1242 if (wait_shm_fd
< 0) {
1244 * Real-only open did not work. It's a failure
1245 * that prohibits using shm.
1247 ERR("Error opening shm %s", sock_info
->wait_shm_path
);
1251 } else if (pid
== 0) {
1255 create_mode
= S_IRUSR
| S_IWUSR
| S_IRGRP
;
1256 if (sock_info
->global
)
1257 create_mode
|= S_IROTH
| S_IWGRP
| S_IWOTH
;
1259 * We're alone in a child process, so we can modify the
1260 * process-wide umask.
1262 umask(~create_mode
);
1264 * Try creating shm (or get rw access).
1265 * We don't do an exclusive open, because we allow other
1266 * processes to create+ftruncate it concurrently.
1268 wait_shm_fd
= shm_open(sock_info
->wait_shm_path
,
1269 O_RDWR
| O_CREAT
, create_mode
);
1270 if (wait_shm_fd
>= 0) {
1271 ret
= ftruncate(wait_shm_fd
, mmap_size
);
1273 PERROR("ftruncate");
1274 _exit(EXIT_FAILURE
);
1276 _exit(EXIT_SUCCESS
);
1279 * For local shm, we need to have rw access to accept
1280 * opening it: this means the local sessiond will be
1281 * able to wake us up. For global shm, we open it even
1282 * if rw access is not granted, because the root.root
1283 * sessiond will be able to override all rights and wake
1286 if (!sock_info
->global
&& errno
!= EACCES
) {
1287 ERR("Error opening shm %s", sock_info
->wait_shm_path
);
1288 _exit(EXIT_FAILURE
);
1291 * The shm exists, but we cannot open it RW. Report
1294 _exit(EXIT_SUCCESS
);
1299 if (wait_shm_fd
>= 0 && !sock_info
->global
) {
1300 struct stat statbuf
;
1303 * Ensure that our user is the owner of the shm file for
1304 * local shm. If we do not own the file, it means our
1305 * sessiond will not have access to wake us up (there is
1306 * probably a rogue process trying to fake our
1307 * sessiond). Fallback to polling method in this case.
1309 ret
= fstat(wait_shm_fd
, &statbuf
);
1314 if (statbuf
.st_uid
!= getuid())
1320 ret
= close(wait_shm_fd
);
1322 PERROR("Error closing fd");
1328 char *get_map_shm(struct sock_info
*sock_info
)
1331 int wait_shm_fd
, ret
;
1332 char *wait_shm_mmap
;
1334 page_size
= sysconf(_SC_PAGE_SIZE
);
1335 if (page_size
<= 0) {
1339 PERROR("Error in sysconf(_SC_PAGE_SIZE)");
1343 lttng_ust_lock_fd_tracker();
1344 wait_shm_fd
= get_wait_shm(sock_info
, page_size
);
1345 if (wait_shm_fd
< 0) {
1346 lttng_ust_unlock_fd_tracker();
1350 ret
= lttng_ust_add_fd_to_tracker(wait_shm_fd
);
1352 ret
= close(wait_shm_fd
);
1354 PERROR("Error closing fd");
1356 lttng_ust_unlock_fd_tracker();
1361 lttng_ust_unlock_fd_tracker();
1363 wait_shm_mmap
= mmap(NULL
, page_size
, PROT_READ
,
1364 MAP_SHARED
, wait_shm_fd
, 0);
1366 /* close shm fd immediately after taking the mmap reference */
1367 lttng_ust_lock_fd_tracker();
1368 ret
= close(wait_shm_fd
);
1370 lttng_ust_delete_fd_from_tracker(wait_shm_fd
);
1372 PERROR("Error closing fd");
1374 lttng_ust_unlock_fd_tracker();
1376 if (wait_shm_mmap
== MAP_FAILED
) {
1377 DBG("mmap error (can be caused by race with sessiond). Fallback to poll mode.");
1380 return wait_shm_mmap
;
1387 void wait_for_sessiond(struct sock_info
*sock_info
)
1389 /* Use ust_lock to check if we should quit. */
1393 if (wait_poll_fallback
) {
1398 assert(sock_info
->wait_shm_mmap
);
1400 DBG("Waiting for %s apps sessiond", sock_info
->name
);
1401 /* Wait for futex wakeup */
1402 if (uatomic_read((int32_t *) sock_info
->wait_shm_mmap
))
1405 while (futex_async((int32_t *) sock_info
->wait_shm_mmap
,
1406 FUTEX_WAIT
, 0, NULL
, NULL
, 0)) {
1409 /* Value already changed. */
1412 /* Retry if interrupted by signal. */
1413 break; /* Get out of switch. */
1415 wait_poll_fallback
= 1;
1417 "Linux kernels 2.6.33 to 3.0 (with the exception of stable versions) "
1418 "do not support FUTEX_WAKE on read-only memory mappings correctly. "
1419 "Please upgrade your kernel "
1420 "(fix is commit 9ea71503a8ed9184d2d0b8ccc4d269d05f7940ae in Linux kernel "
1421 "mainline). LTTng-UST will use polling mode fallback.");
1440 * This thread does not allocate any resource, except within
1441 * handle_message, within mutex protection. This mutex protects against
1443 * The other moment it allocates resources is at socket connection, which
1444 * is also protected by the mutex.
1447 void *ust_listener_thread(void *arg
)
1449 struct sock_info
*sock_info
= arg
;
1450 int sock
, ret
, prev_connect_failed
= 0, has_waited
= 0, fd
;
1453 lttng_ust_fixup_tls();
1455 * If available, add '-ust' to the end of this thread's
1458 ret
= lttng_ust_setustprocname();
1460 ERR("Unable to set UST process name");
1463 /* Restart trying to connect to the session daemon */
1465 if (prev_connect_failed
) {
1466 /* Wait for sessiond availability with pipe */
1467 wait_for_sessiond(sock_info
);
1471 * Sleep for 5 seconds before retrying after a
1472 * sequence of failure / wait / failure. This
1473 * deals with a killed or broken session daemon.
1479 prev_connect_failed
= 0;
1486 if (sock_info
->socket
!= -1) {
1487 /* FD tracker is updated by ustcomm_close_unix_sock() */
1488 ret
= ustcomm_close_unix_sock(sock_info
->socket
);
1490 ERR("Error closing %s ust cmd socket",
1493 sock_info
->socket
= -1;
1495 if (sock_info
->notify_socket
!= -1) {
1496 /* FD tracker is updated by ustcomm_close_unix_sock() */
1497 ret
= ustcomm_close_unix_sock(sock_info
->notify_socket
);
1499 ERR("Error closing %s ust notify socket",
1502 sock_info
->notify_socket
= -1;
1507 * Register. We need to perform both connect and sending
1508 * registration message before doing the next connect otherwise
1509 * we may reach unix socket connect queue max limits and block
1510 * on the 2nd connect while the session daemon is awaiting the
1511 * first connect registration message.
1513 /* Connect cmd socket */
1514 lttng_ust_lock_fd_tracker();
1515 ret
= ustcomm_connect_unix_sock(sock_info
->sock_path
,
1516 get_connect_sock_timeout());
1518 lttng_ust_unlock_fd_tracker();
1519 DBG("Info: sessiond not accepting connections to %s apps socket", sock_info
->name
);
1520 prev_connect_failed
= 1;
1523 * If we cannot find the sessiond daemon, don't delay
1524 * constructor execution.
1526 ret
= handle_register_failed(sock_info
);
1532 ret
= lttng_ust_add_fd_to_tracker(fd
);
1536 PERROR("close on sock_info->socket");
1539 lttng_ust_unlock_fd_tracker();
1544 sock_info
->socket
= ret
;
1545 lttng_ust_unlock_fd_tracker();
1549 * Unlock/relock ust lock because connect is blocking (with
1550 * timeout). Don't delay constructors on the ust lock for too
1558 * Create only one root handle per listener thread for the whole
1559 * process lifetime, so we ensure we get ID which is statically
1560 * assigned to the root handle.
1562 if (sock_info
->root_handle
== -1) {
1563 ret
= lttng_abi_create_root_handle();
1565 ERR("Error creating root handle");
1568 sock_info
->root_handle
= ret
;
1571 ret
= register_to_sessiond(sock_info
->socket
, USTCTL_SOCKET_CMD
);
1573 ERR("Error registering to %s ust cmd socket",
1575 prev_connect_failed
= 1;
1577 * If we cannot register to the sessiond daemon, don't
1578 * delay constructor execution.
1580 ret
= handle_register_failed(sock_info
);
1588 * Unlock/relock ust lock because connect is blocking (with
1589 * timeout). Don't delay constructors on the ust lock for too
1596 /* Connect notify socket */
1597 lttng_ust_lock_fd_tracker();
1598 ret
= ustcomm_connect_unix_sock(sock_info
->sock_path
,
1599 get_connect_sock_timeout());
1601 lttng_ust_unlock_fd_tracker();
1602 DBG("Info: sessiond not accepting connections to %s apps socket", sock_info
->name
);
1603 prev_connect_failed
= 1;
1606 * If we cannot find the sessiond daemon, don't delay
1607 * constructor execution.
1609 ret
= handle_register_failed(sock_info
);
1616 ret
= lttng_ust_add_fd_to_tracker(fd
);
1620 PERROR("close on sock_info->notify_socket");
1623 lttng_ust_unlock_fd_tracker();
1628 sock_info
->notify_socket
= ret
;
1629 lttng_ust_unlock_fd_tracker();
1633 * Unlock/relock ust lock because connect is blocking (with
1634 * timeout). Don't delay constructors on the ust lock for too
1641 timeout
= get_notify_sock_timeout();
1644 * Give at least 10ms to sessiond to reply to
1649 ret
= ustcomm_setsockopt_rcv_timeout(sock_info
->notify_socket
,
1652 WARN("Error setting socket receive timeout");
1654 ret
= ustcomm_setsockopt_snd_timeout(sock_info
->notify_socket
,
1657 WARN("Error setting socket send timeout");
1659 } else if (timeout
< -1) {
1660 WARN("Unsupported timeout value %ld", timeout
);
1663 ret
= register_to_sessiond(sock_info
->notify_socket
,
1664 USTCTL_SOCKET_NOTIFY
);
1666 ERR("Error registering to %s ust notify socket",
1668 prev_connect_failed
= 1;
1670 * If we cannot register to the sessiond daemon, don't
1671 * delay constructor execution.
1673 ret
= handle_register_failed(sock_info
);
1678 sock
= sock_info
->socket
;
1684 struct ustcomm_ust_msg lum
;
1686 len
= ustcomm_recv_unix_sock(sock
, &lum
, sizeof(lum
));
1688 case 0: /* orderly shutdown */
1689 DBG("%s lttng-sessiond has performed an orderly shutdown", sock_info
->name
);
1694 * Either sessiond has shutdown or refused us by closing the socket.
1695 * In either case, we don't want to delay construction execution,
1696 * and we need to wait before retry.
1698 prev_connect_failed
= 1;
1700 * If we cannot register to the sessiond daemon, don't
1701 * delay constructor execution.
1703 ret
= handle_register_failed(sock_info
);
1708 print_cmd(lum
.cmd
, lum
.handle
);
1709 ret
= handle_message(sock_info
, sock
, &lum
);
1711 ERR("Error handling message for %s socket",
1714 * Close socket if protocol error is
1722 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len
);
1724 DBG("incorrect message size (%s socket): %zd", sock_info
->name
, len
);
1726 if (len
== -ECONNRESET
) {
1727 DBG("%s remote end closed connection", sock_info
->name
);
1738 /* Cleanup socket handles before trying to reconnect */
1739 lttng_ust_objd_table_owner_cleanup(sock_info
);
1741 goto restart
; /* try to reconnect */
1746 pthread_mutex_lock(&ust_exit_mutex
);
1747 sock_info
->thread_active
= 0;
1748 pthread_mutex_unlock(&ust_exit_mutex
);
1753 * Weak symbol to call when the ust malloc wrapper is not loaded.
1755 __attribute__((weak
))
1756 void lttng_ust_malloc_wrapper_init(void)
1761 * sessiond monitoring thread: monitor presence of global and per-user
1762 * sessiond by polling the application common named pipe.
1764 void __attribute__((constructor
)) lttng_ust_init(void)
1766 struct timespec constructor_timeout
;
1767 sigset_t sig_all_blocked
, orig_parent_mask
;
1768 pthread_attr_t thread_attr
;
1773 if (uatomic_xchg(&initialized
, 1) == 1)
1777 * Fixup interdependency between TLS fixup mutex (which happens
1778 * to be the dynamic linker mutex) and ust_lock, taken within
1781 lttng_ust_fixup_tls();
1783 lttng_ust_loaded
= 1;
1786 * We need to ensure that the liblttng-ust library is not unloaded to avoid
1787 * the unloading of code used by the ust_listener_threads as we can not
1788 * reliably know when they exited. To do that, manually load
1789 * liblttng-ust.so to increment the dynamic loader's internal refcount for
1790 * this library so it never becomes zero, thus never gets unloaded from the
1791 * address space of the process. Since we are already running in the
1792 * constructor of the LTTNG_UST_LIB_SO_NAME library, calling dlopen will
1793 * simply increment the refcount and no additionnal work is needed by the
1794 * dynamic loader as the shared library is already loaded in the address
1795 * space. As a safe guard, we use the RTLD_NODELETE flag to prevent
1796 * unloading of the UST library if its refcount becomes zero (which should
1797 * never happen). Do the return value check but discard the handle at the
1798 * end of the function as it's not needed.
1800 handle
= dlopen(LTTNG_UST_LIB_SO_NAME
, RTLD_LAZY
| RTLD_NODELETE
);
1802 ERR("dlopen of liblttng-ust shared library (%s).", LTTNG_UST_LIB_SO_NAME
);
1806 * We want precise control over the order in which we construct
1807 * our sub-libraries vs starting to receive commands from
1808 * sessiond (otherwise leading to errors when trying to create
1809 * sessiond before the init functions are completed).
1812 lttng_ust_getenv_init(); /* Needs init_usterr() to be completed. */
1814 lttng_ust_init_fd_tracker();
1815 lttng_ust_clock_init();
1816 lttng_ust_getcpu_init();
1817 lttng_ust_statedump_init();
1818 lttng_ring_buffer_metadata_client_init();
1819 lttng_ring_buffer_client_overwrite_init();
1820 lttng_ring_buffer_client_overwrite_rt_init();
1821 lttng_ring_buffer_client_discard_init();
1822 lttng_ring_buffer_client_discard_rt_init();
1823 lttng_perf_counter_init();
1825 * Invoke ust malloc wrapper init before starting other threads.
1827 lttng_ust_malloc_wrapper_init();
1829 timeout_mode
= get_constructor_timeout(&constructor_timeout
);
1831 get_allow_blocking();
1833 ret
= sem_init(&constructor_wait
, 0, 0);
1838 ret
= setup_global_apps();
1840 assert(global_apps
.allowed
== 0);
1841 DBG("global apps setup returned %d", ret
);
1844 ret
= setup_local_apps();
1846 assert(local_apps
.allowed
== 0);
1847 DBG("local apps setup returned %d", ret
);
1850 /* A new thread created by pthread_create inherits the signal mask
1851 * from the parent. To avoid any signal being received by the
1852 * listener thread, we block all signals temporarily in the parent,
1853 * while we create the listener thread.
1855 sigfillset(&sig_all_blocked
);
1856 ret
= pthread_sigmask(SIG_SETMASK
, &sig_all_blocked
, &orig_parent_mask
);
1858 ERR("pthread_sigmask: %s", strerror(ret
));
1861 ret
= pthread_attr_init(&thread_attr
);
1863 ERR("pthread_attr_init: %s", strerror(ret
));
1865 ret
= pthread_attr_setdetachstate(&thread_attr
, PTHREAD_CREATE_DETACHED
);
1867 ERR("pthread_attr_setdetachstate: %s", strerror(ret
));
1870 if (global_apps
.allowed
) {
1871 pthread_mutex_lock(&ust_exit_mutex
);
1872 ret
= pthread_create(&global_apps
.ust_listener
, &thread_attr
,
1873 ust_listener_thread
, &global_apps
);
1875 ERR("pthread_create global: %s", strerror(ret
));
1877 global_apps
.thread_active
= 1;
1878 pthread_mutex_unlock(&ust_exit_mutex
);
1880 handle_register_done(&global_apps
);
1883 if (local_apps
.allowed
) {
1884 pthread_mutex_lock(&ust_exit_mutex
);
1885 ret
= pthread_create(&local_apps
.ust_listener
, &thread_attr
,
1886 ust_listener_thread
, &local_apps
);
1888 ERR("pthread_create local: %s", strerror(ret
));
1890 local_apps
.thread_active
= 1;
1891 pthread_mutex_unlock(&ust_exit_mutex
);
1893 handle_register_done(&local_apps
);
1895 ret
= pthread_attr_destroy(&thread_attr
);
1897 ERR("pthread_attr_destroy: %s", strerror(ret
));
1900 /* Restore original signal mask in parent */
1901 ret
= pthread_sigmask(SIG_SETMASK
, &orig_parent_mask
, NULL
);
1903 ERR("pthread_sigmask: %s", strerror(ret
));
1906 switch (timeout_mode
) {
1907 case 1: /* timeout wait */
1909 ret
= sem_timedwait(&constructor_wait
,
1910 &constructor_timeout
);
1911 } while (ret
< 0 && errno
== EINTR
);
1915 ERR("Timed out waiting for lttng-sessiond");
1918 PERROR("sem_timedwait");
1921 ERR("Unexpected error \"%s\" returned by sem_timedwait",
1926 case -1:/* wait forever */
1928 ret
= sem_wait(&constructor_wait
);
1929 } while (ret
< 0 && errno
== EINTR
);
1936 ERR("Unexpected error \"%s\" returned by sem_wait",
1941 case 0: /* no timeout */
1947 void lttng_ust_cleanup(int exiting
)
1949 cleanup_sock_info(&global_apps
, exiting
);
1950 cleanup_sock_info(&local_apps
, exiting
);
1951 local_apps
.allowed
= 0;
1952 global_apps
.allowed
= 0;
1954 * The teardown in this function all affect data structures
1955 * accessed under the UST lock by the listener thread. This
1956 * lock, along with the lttng_ust_comm_should_quit flag, ensure
1957 * that none of these threads are accessing this data at this
1960 lttng_ust_abi_exit();
1961 lttng_ust_events_exit();
1962 lttng_perf_counter_exit();
1963 lttng_ring_buffer_client_discard_rt_exit();
1964 lttng_ring_buffer_client_discard_exit();
1965 lttng_ring_buffer_client_overwrite_rt_exit();
1966 lttng_ring_buffer_client_overwrite_exit();
1967 lttng_ring_buffer_metadata_client_exit();
1968 lttng_ust_statedump_destroy();
1971 /* Reinitialize values for fork */
1972 sem_count
= sem_count_initial_value
;
1973 lttng_ust_comm_should_quit
= 0;
1978 void __attribute__((destructor
)) lttng_ust_exit(void)
1983 * Using pthread_cancel here because:
1984 * A) we don't want to hang application teardown.
1985 * B) the thread is not allocating any resource.
1989 * Require the communication thread to quit. Synchronize with
1990 * mutexes to ensure it is not in a mutex critical section when
1991 * pthread_cancel is later called.
1994 lttng_ust_comm_should_quit
= 1;
1997 pthread_mutex_lock(&ust_exit_mutex
);
1998 /* cancel threads */
1999 if (global_apps
.thread_active
) {
2000 ret
= pthread_cancel(global_apps
.ust_listener
);
2002 ERR("Error cancelling global ust listener thread: %s",
2005 global_apps
.thread_active
= 0;
2008 if (local_apps
.thread_active
) {
2009 ret
= pthread_cancel(local_apps
.ust_listener
);
2011 ERR("Error cancelling local ust listener thread: %s",
2014 local_apps
.thread_active
= 0;
2017 pthread_mutex_unlock(&ust_exit_mutex
);
2020 * Do NOT join threads: use of sys_futex makes it impossible to
2021 * join the threads without using async-cancel, but async-cancel
2022 * is delivered by a signal, which could hit the target thread
2023 * anywhere in its code path, including while the ust_lock() is
2024 * held, causing a deadlock for the other thread. Let the OS
2025 * cleanup the threads if there are stalled in a syscall.
2027 lttng_ust_cleanup(1);
2031 * We exclude the worker threads across fork and clone (except
2032 * CLONE_VM), because these system calls only keep the forking thread
2033 * running in the child. Therefore, we don't want to call fork or clone
2034 * in the middle of an tracepoint or ust tracing state modification.
2035 * Holding this mutex protects these structures across fork and clone.
2037 void ust_before_fork(sigset_t
*save_sigset
)
2040 * Disable signals. This is to avoid that the child intervenes
2041 * before it is properly setup for tracing. It is safer to
2042 * disable all signals, because then we know we are not breaking
2043 * anything by restoring the original mask.
2048 /* Fixup lttng-ust TLS. */
2049 lttng_ust_fixup_tls();
2051 if (URCU_TLS(lttng_ust_nest_count
))
2053 /* Disable signals */
2054 sigfillset(&all_sigs
);
2055 ret
= sigprocmask(SIG_BLOCK
, &all_sigs
, save_sigset
);
2057 PERROR("sigprocmask");
2060 pthread_mutex_lock(&ust_fork_mutex
);
2063 rcu_bp_before_fork();
2066 static void ust_after_fork_common(sigset_t
*restore_sigset
)
2070 DBG("process %d", getpid());
2073 pthread_mutex_unlock(&ust_fork_mutex
);
2075 /* Restore signals */
2076 ret
= sigprocmask(SIG_SETMASK
, restore_sigset
, NULL
);
2078 PERROR("sigprocmask");
2082 void ust_after_fork_parent(sigset_t
*restore_sigset
)
2084 if (URCU_TLS(lttng_ust_nest_count
))
2086 DBG("process %d", getpid());
2087 rcu_bp_after_fork_parent();
2088 /* Release mutexes and reenable signals */
2089 ust_after_fork_common(restore_sigset
);
2093 * After fork, in the child, we need to cleanup all the leftover state,
2094 * except the worker thread which already magically disappeared thanks
2095 * to the weird Linux fork semantics. After tyding up, we call
2096 * lttng_ust_init() again to start over as a new PID.
2098 * This is meant for forks() that have tracing in the child between the
2099 * fork and following exec call (if there is any).
2101 void ust_after_fork_child(sigset_t
*restore_sigset
)
2103 if (URCU_TLS(lttng_ust_nest_count
))
2105 lttng_context_vpid_reset();
2106 lttng_context_vtid_reset();
2107 lttng_context_procname_reset();
2108 DBG("process %d", getpid());
2109 /* Release urcu mutexes */
2110 rcu_bp_after_fork_child();
2111 lttng_ust_cleanup(0);
2112 /* Release mutexes and reenable signals */
2113 ust_after_fork_common(restore_sigset
);
2117 void lttng_ust_sockinfo_session_enabled(void *owner
)
2119 struct sock_info
*sock_info
= owner
;
2120 sock_info
->statedump_pending
= 1;