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
23 #include <sys/types.h>
24 #include <sys/socket.h>
27 #include <sys/types.h>
33 #include <semaphore.h>
37 #include <urcu/uatomic.h>
38 #include <urcu/futex.h>
39 #include <urcu/compiler.h>
41 #include <lttng/ust-events.h>
42 #include <lttng/ust-abi.h>
43 #include <lttng/ust.h>
44 #include <lttng/ust-error.h>
45 #include <lttng/ust-ctl.h>
46 #include <urcu/tls-compat.h>
48 #include <usterr-signal-safe.h>
50 #include "tracepoint-internal.h"
51 #include "lttng-tracer-core.h"
53 #include "../libringbuffer/tlsfixup.h"
56 * Has lttng ust comm constructor been called ?
58 static int initialized
;
61 * The ust_lock/ust_unlock lock is used as a communication thread mutex.
62 * Held when handling a command, also held by fork() to deal with
63 * removal of threads, and by exit path.
66 /* Should the ust comm thread quit ? */
67 static int lttng_ust_comm_should_quit
;
70 * Wait for either of these before continuing to the main
72 * - the register_done message from sessiond daemon
73 * (will let the sessiond daemon enable sessions before main
75 * - sessiond daemon is not reachable.
76 * - timeout (ensuring applications are resilient to session
79 static sem_t constructor_wait
;
81 * Doing this for both the global and local sessiond.
83 static int sem_count
= { 2 };
86 * Counting nesting within lttng-ust. Used to ensure that calling fork()
87 * from liblttng-ust does not execute the pre/post fork handlers.
89 static DEFINE_URCU_TLS(int, lttng_ust_nest_count
);
92 * Info about socket and associated listener thread.
96 pthread_t ust_listener
; /* listener thread */
98 int constructor_sem_posted
;
103 char sock_path
[PATH_MAX
];
107 char wait_shm_path
[PATH_MAX
];
111 /* Socket from app (connect) to session daemon (listen) for communication */
112 struct sock_info global_apps
= {
120 .sock_path
= LTTNG_DEFAULT_RUNDIR
"/" LTTNG_UST_SOCK_FILENAME
,
124 .wait_shm_path
= "/" LTTNG_UST_WAIT_FILENAME
,
127 /* TODO: allow global_apps_sock_path override */
129 struct sock_info local_apps
= {
133 .allowed
= 0, /* Check setuid bit first */
140 static int wait_poll_fallback
;
142 static const char *cmd_name_mapping
[] = {
143 [ LTTNG_UST_RELEASE
] = "Release",
144 [ LTTNG_UST_SESSION
] = "Create Session",
145 [ LTTNG_UST_TRACER_VERSION
] = "Get Tracer Version",
147 [ LTTNG_UST_TRACEPOINT_LIST
] = "Create Tracepoint List",
148 [ LTTNG_UST_WAIT_QUIESCENT
] = "Wait for Quiescent State",
149 [ LTTNG_UST_REGISTER_DONE
] = "Registration Done",
150 [ LTTNG_UST_TRACEPOINT_FIELD_LIST
] = "Create Tracepoint Field List",
152 /* Session FD commands */
153 [ LTTNG_UST_CHANNEL
] = "Create Channel",
154 [ LTTNG_UST_SESSION_START
] = "Start Session",
155 [ LTTNG_UST_SESSION_STOP
] = "Stop Session",
157 /* Channel FD commands */
158 [ LTTNG_UST_STREAM
] = "Create Stream",
159 [ LTTNG_UST_EVENT
] = "Create Event",
161 /* Event and Channel FD commands */
162 [ LTTNG_UST_CONTEXT
] = "Create Context",
163 [ LTTNG_UST_FLUSH_BUFFER
] = "Flush Buffer",
165 /* Event, Channel and Session commands */
166 [ LTTNG_UST_ENABLE
] = "Enable",
167 [ LTTNG_UST_DISABLE
] = "Disable",
169 /* Tracepoint list commands */
170 [ LTTNG_UST_TRACEPOINT_LIST_GET
] = "List Next Tracepoint",
171 [ LTTNG_UST_TRACEPOINT_FIELD_LIST_GET
] = "List Next Tracepoint Field",
173 /* Event FD commands */
174 [ LTTNG_UST_FILTER
] = "Create Filter",
177 extern void lttng_ring_buffer_client_overwrite_init(void);
178 extern void lttng_ring_buffer_client_discard_init(void);
179 extern void lttng_ring_buffer_metadata_client_init(void);
180 extern void lttng_ring_buffer_client_overwrite_exit(void);
181 extern void lttng_ring_buffer_client_discard_exit(void);
182 extern void lttng_ring_buffer_metadata_client_exit(void);
185 * Force a read (imply TLS fixup for dlopen) of TLS variables.
188 void lttng_fixup_nest_count_tls(void)
190 asm volatile ("" : : "m" (URCU_TLS(lttng_ust_nest_count
)));
193 int lttng_get_notify_socket(void *owner
)
195 struct sock_info
*info
= owner
;
197 return info
->notify_socket
;
201 void print_cmd(int cmd
, int handle
)
203 const char *cmd_name
= "Unknown";
205 if (cmd_name_mapping
[cmd
]) {
206 cmd_name
= cmd_name_mapping
[cmd
];
208 DBG("Message Received \"%s\", Handle \"%s\" (%d)", cmd_name
,
209 lttng_ust_obj_get_name(handle
), handle
);
213 int setup_local_apps(void)
215 const char *home_dir
;
220 * Disallow per-user tracing for setuid binaries.
222 if (uid
!= geteuid()) {
223 assert(local_apps
.allowed
== 0);
226 home_dir
= (const char *) getenv("HOME");
228 WARN("HOME environment variable not set. Disabling LTTng-UST per-user tracing.");
229 assert(local_apps
.allowed
== 0);
232 local_apps
.allowed
= 1;
233 snprintf(local_apps
.sock_path
, PATH_MAX
, "%s/%s/%s",
235 LTTNG_DEFAULT_HOME_RUNDIR
,
236 LTTNG_UST_SOCK_FILENAME
);
237 snprintf(local_apps
.wait_shm_path
, PATH_MAX
, "/%s-%u",
238 LTTNG_UST_WAIT_FILENAME
,
244 int register_to_sessiond(int socket
, enum ustctl_socket_type type
)
246 return ustcomm_send_reg_msg(socket
,
249 lttng_alignof(uint8_t) * CHAR_BIT
,
250 lttng_alignof(uint16_t) * CHAR_BIT
,
251 lttng_alignof(uint32_t) * CHAR_BIT
,
252 lttng_alignof(uint64_t) * CHAR_BIT
,
253 lttng_alignof(unsigned long) * CHAR_BIT
);
257 int send_reply(int sock
, struct ustcomm_ust_reply
*lur
)
261 len
= ustcomm_send_unix_sock(sock
, lur
, sizeof(*lur
));
264 DBG("message successfully sent");
267 if (len
== -ECONNRESET
) {
268 DBG("remote end closed connection");
273 DBG("incorrect message size: %zd", len
);
279 int handle_register_done(struct sock_info
*sock_info
)
283 if (sock_info
->constructor_sem_posted
)
285 sock_info
->constructor_sem_posted
= 1;
286 if (uatomic_read(&sem_count
) <= 0) {
289 ret
= uatomic_add_return(&sem_count
, -1);
291 ret
= sem_post(&constructor_wait
);
298 int handle_message(struct sock_info
*sock_info
,
299 int sock
, struct ustcomm_ust_msg
*lum
)
302 const struct lttng_ust_objd_ops
*ops
;
303 struct ustcomm_ust_reply lur
;
309 memset(&lur
, 0, sizeof(lur
));
311 if (lttng_ust_comm_should_quit
) {
312 ret
= -LTTNG_UST_ERR_EXITING
;
316 ops
= objd_ops(lum
->handle
);
323 case LTTNG_UST_REGISTER_DONE
:
324 if (lum
->handle
== LTTNG_UST_ROOT_HANDLE
)
325 ret
= handle_register_done(sock_info
);
329 case LTTNG_UST_RELEASE
:
330 if (lum
->handle
== LTTNG_UST_ROOT_HANDLE
)
333 ret
= lttng_ust_objd_unref(lum
->handle
);
335 case LTTNG_UST_FILTER
:
337 /* Receive filter data */
338 struct lttng_ust_filter_bytecode_node
*bytecode
;
340 if (lum
->u
.filter
.data_size
> FILTER_BYTECODE_MAX_LEN
) {
341 ERR("Filter data size is too large: %u bytes",
342 lum
->u
.filter
.data_size
);
347 if (lum
->u
.filter
.reloc_offset
> lum
->u
.filter
.data_size
) {
348 ERR("Filter reloc offset %u is not within data",
349 lum
->u
.filter
.reloc_offset
);
354 bytecode
= zmalloc(sizeof(*bytecode
) + lum
->u
.filter
.data_size
);
359 len
= ustcomm_recv_unix_sock(sock
, bytecode
->bc
.data
,
360 lum
->u
.filter
.data_size
);
362 case 0: /* orderly shutdown */
367 if (len
== lum
->u
.filter
.data_size
) {
368 DBG("filter data received");
370 } else if (len
< 0) {
371 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len
);
372 if (len
== -ECONNRESET
) {
373 ERR("%s remote end closed connection", sock_info
->name
);
381 DBG("incorrect filter data message size: %zd", len
);
387 bytecode
->bc
.len
= lum
->u
.filter
.data_size
;
388 bytecode
->bc
.reloc_offset
= lum
->u
.filter
.reloc_offset
;
389 bytecode
->bc
.seqnum
= lum
->u
.filter
.seqnum
;
391 ret
= ops
->cmd(lum
->handle
, lum
->cmd
,
392 (unsigned long) bytecode
,
397 /* don't free bytecode if everything went fine. */
404 case LTTNG_UST_CHANNEL
:
408 len
= ustcomm_recv_channel_from_sessiond(sock
,
409 &chan_data
, lum
->u
.channel
.len
);
411 case 0: /* orderly shutdown */
415 if (len
== lum
->u
.channel
.len
) {
416 DBG("channel data received");
418 } else if (len
< 0) {
419 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len
);
420 if (len
== -ECONNRESET
) {
421 ERR("%s remote end closed connection", sock_info
->name
);
428 DBG("incorrect channel data message size: %zd", len
);
433 args
.channel
.chan_data
= chan_data
;
435 ret
= ops
->cmd(lum
->handle
, lum
->cmd
,
436 (unsigned long) &lum
->u
,
442 case LTTNG_UST_STREAM
:
444 /* Receive shm_fd, wakeup_fd */
445 ret
= ustcomm_recv_stream_from_sessiond(sock
,
448 &args
.stream
.wakeup_fd
);
453 ret
= ops
->cmd(lum
->handle
, lum
->cmd
,
454 (unsigned long) &lum
->u
,
462 ret
= ops
->cmd(lum
->handle
, lum
->cmd
,
463 (unsigned long) &lum
->u
,
471 lur
.handle
= lum
->handle
;
475 lur
.ret_code
= LTTNG_UST_OK
;
478 * Use -LTTNG_UST_ERR as wildcard for UST internal
479 * error that are not caused by the transport, except if
480 * we already have a more precise error message to
483 if (ret
> -LTTNG_UST_ERR
) {
484 /* Translate code to UST error. */
487 lur
.ret_code
= -LTTNG_UST_ERR_EXIST
;
490 lur
.ret_code
= -LTTNG_UST_ERR_INVAL
;
493 lur
.ret_code
= -LTTNG_UST_ERR_NOENT
;
496 lur
.ret_code
= -LTTNG_UST_ERR_PERM
;
499 lur
.ret_code
= -LTTNG_UST_ERR_NOSYS
;
502 lur
.ret_code
= -LTTNG_UST_ERR
;
511 case LTTNG_UST_TRACER_VERSION
:
512 lur
.u
.version
= lum
->u
.version
;
514 case LTTNG_UST_TRACEPOINT_LIST_GET
:
515 memcpy(&lur
.u
.tracepoint
, &lum
->u
.tracepoint
, sizeof(lur
.u
.tracepoint
));
519 DBG("Return value: %d", lur
.ret_val
);
520 ret
= send_reply(sock
, &lur
);
522 DBG("error sending reply");
527 * LTTNG_UST_TRACEPOINT_FIELD_LIST_GET needs to send the field
530 if (lur
.ret_code
== LTTNG_UST_OK
) {
532 case LTTNG_UST_TRACEPOINT_FIELD_LIST_GET
:
533 len
= ustcomm_send_unix_sock(sock
,
534 &args
.field_list
.entry
,
535 sizeof(args
.field_list
.entry
));
540 if (len
!= sizeof(args
.field_list
.entry
)) {
553 void cleanup_sock_info(struct sock_info
*sock_info
, int exiting
)
557 if (sock_info
->socket
!= -1) {
558 ret
= ustcomm_close_unix_sock(sock_info
->socket
);
560 ERR("Error closing ust cmd socket");
562 sock_info
->socket
= -1;
564 if (sock_info
->notify_socket
!= -1) {
565 ret
= ustcomm_close_unix_sock(sock_info
->notify_socket
);
567 ERR("Error closing ust notify socket");
569 sock_info
->notify_socket
= -1;
571 if (sock_info
->root_handle
!= -1) {
572 ret
= lttng_ust_objd_unref(sock_info
->root_handle
);
574 ERR("Error unref root handle");
576 sock_info
->root_handle
= -1;
578 sock_info
->constructor_sem_posted
= 0;
580 * wait_shm_mmap is used by listener threads outside of the
581 * ust lock, so we cannot tear it down ourselves, because we
582 * cannot join on these threads. Leave this task to the OS
585 if (!exiting
&& sock_info
->wait_shm_mmap
) {
586 ret
= munmap(sock_info
->wait_shm_mmap
, sysconf(_SC_PAGE_SIZE
));
588 ERR("Error unmapping wait shm");
590 sock_info
->wait_shm_mmap
= NULL
;
595 * Using fork to set umask in the child process (not multi-thread safe).
596 * We deal with the shm_open vs ftruncate race (happening when the
597 * sessiond owns the shm and does not let everybody modify it, to ensure
598 * safety against shm_unlink) by simply letting the mmap fail and
599 * retrying after a few seconds.
600 * For global shm, everybody has rw access to it until the sessiond
604 int get_wait_shm(struct sock_info
*sock_info
, size_t mmap_size
)
606 int wait_shm_fd
, ret
;
610 * Try to open read-only.
612 wait_shm_fd
= shm_open(sock_info
->wait_shm_path
, O_RDONLY
, 0);
613 if (wait_shm_fd
>= 0) {
615 } else if (wait_shm_fd
< 0 && errno
!= ENOENT
) {
617 * Real-only open did not work, and it's not because the
618 * entry was not present. It's a failure that prohibits
621 ERR("Error opening shm %s", sock_info
->wait_shm_path
);
625 * If the open failed because the file did not exist, try
626 * creating it ourself.
628 URCU_TLS(lttng_ust_nest_count
)++;
630 URCU_TLS(lttng_ust_nest_count
)--;
635 * Parent: wait for child to return, in which case the
636 * shared memory map will have been created.
639 if (pid
< 0 || !WIFEXITED(status
) || WEXITSTATUS(status
) != 0) {
644 * Try to open read-only again after creation.
646 wait_shm_fd
= shm_open(sock_info
->wait_shm_path
, O_RDONLY
, 0);
647 if (wait_shm_fd
< 0) {
649 * Real-only open did not work. It's a failure
650 * that prohibits using shm.
652 ERR("Error opening shm %s", sock_info
->wait_shm_path
);
656 } else if (pid
== 0) {
660 create_mode
= S_IRUSR
| S_IWUSR
| S_IRGRP
;
661 if (sock_info
->global
)
662 create_mode
|= S_IROTH
| S_IWGRP
| S_IWOTH
;
664 * We're alone in a child process, so we can modify the
665 * process-wide umask.
669 * Try creating shm (or get rw access).
670 * We don't do an exclusive open, because we allow other
671 * processes to create+ftruncate it concurrently.
673 wait_shm_fd
= shm_open(sock_info
->wait_shm_path
,
674 O_RDWR
| O_CREAT
, create_mode
);
675 if (wait_shm_fd
>= 0) {
676 ret
= ftruncate(wait_shm_fd
, mmap_size
);
684 * For local shm, we need to have rw access to accept
685 * opening it: this means the local sessiond will be
686 * able to wake us up. For global shm, we open it even
687 * if rw access is not granted, because the root.root
688 * sessiond will be able to override all rights and wake
691 if (!sock_info
->global
&& errno
!= EACCES
) {
692 ERR("Error opening shm %s", sock_info
->wait_shm_path
);
696 * The shm exists, but we cannot open it RW. Report
704 if (wait_shm_fd
>= 0 && !sock_info
->global
) {
708 * Ensure that our user is the owner of the shm file for
709 * local shm. If we do not own the file, it means our
710 * sessiond will not have access to wake us up (there is
711 * probably a rogue process trying to fake our
712 * sessiond). Fallback to polling method in this case.
714 ret
= fstat(wait_shm_fd
, &statbuf
);
719 if (statbuf
.st_uid
!= getuid())
725 ret
= close(wait_shm_fd
);
727 PERROR("Error closing fd");
733 char *get_map_shm(struct sock_info
*sock_info
)
735 size_t mmap_size
= sysconf(_SC_PAGE_SIZE
);
736 int wait_shm_fd
, ret
;
739 wait_shm_fd
= get_wait_shm(sock_info
, mmap_size
);
740 if (wait_shm_fd
< 0) {
743 wait_shm_mmap
= mmap(NULL
, mmap_size
, PROT_READ
,
744 MAP_SHARED
, wait_shm_fd
, 0);
745 /* close shm fd immediately after taking the mmap reference */
746 ret
= close(wait_shm_fd
);
748 PERROR("Error closing fd");
750 if (wait_shm_mmap
== MAP_FAILED
) {
751 DBG("mmap error (can be caused by race with sessiond). Fallback to poll mode.");
754 return wait_shm_mmap
;
761 void wait_for_sessiond(struct sock_info
*sock_info
)
766 if (lttng_ust_comm_should_quit
) {
769 if (wait_poll_fallback
) {
772 if (!sock_info
->wait_shm_mmap
) {
773 sock_info
->wait_shm_mmap
= get_map_shm(sock_info
);
774 if (!sock_info
->wait_shm_mmap
)
779 DBG("Waiting for %s apps sessiond", sock_info
->name
);
780 /* Wait for futex wakeup */
781 if (uatomic_read((int32_t *) sock_info
->wait_shm_mmap
) == 0) {
782 ret
= futex_async((int32_t *) sock_info
->wait_shm_mmap
,
783 FUTEX_WAIT
, 0, NULL
, NULL
, 0);
785 if (errno
== EFAULT
) {
786 wait_poll_fallback
= 1;
788 "Linux kernels 2.6.33 to 3.0 (with the exception of stable versions) "
789 "do not support FUTEX_WAKE on read-only memory mappings correctly. "
790 "Please upgrade your kernel "
791 "(fix is commit 9ea71503a8ed9184d2d0b8ccc4d269d05f7940ae in Linux kernel "
792 "mainline). LTTng-UST will use polling mode fallback.");
810 * This thread does not allocate any resource, except within
811 * handle_message, within mutex protection. This mutex protects against
813 * The other moment it allocates resources is at socket connection, which
814 * is also protected by the mutex.
817 void *ust_listener_thread(void *arg
)
819 struct sock_info
*sock_info
= arg
;
820 int sock
, ret
, prev_connect_failed
= 0, has_waited
= 0;
824 /* Restart trying to connect to the session daemon */
826 if (prev_connect_failed
) {
827 /* Wait for sessiond availability with pipe */
828 wait_for_sessiond(sock_info
);
832 * Sleep for 5 seconds before retrying after a
833 * sequence of failure / wait / failure. This
834 * deals with a killed or broken session daemon.
839 prev_connect_failed
= 0;
843 if (lttng_ust_comm_should_quit
) {
847 if (sock_info
->socket
!= -1) {
848 ret
= ustcomm_close_unix_sock(sock_info
->socket
);
850 ERR("Error closing %s ust cmd socket",
853 sock_info
->socket
= -1;
855 if (sock_info
->notify_socket
!= -1) {
856 ret
= ustcomm_close_unix_sock(sock_info
->notify_socket
);
858 ERR("Error closing %s ust notify socket",
861 sock_info
->notify_socket
= -1;
865 for (i
= 0; i
< 2; i
++) {
866 ret
= ustcomm_connect_unix_sock(sock_info
->sock_path
);
868 DBG("Info: sessiond not accepting connections to %s apps socket", sock_info
->name
);
869 prev_connect_failed
= 1;
871 * If we cannot find the sessiond daemon, don't delay
872 * constructor execution.
874 ret
= handle_register_done(sock_info
);
882 sock_info
->socket
= open_sock
[0];
883 sock_info
->notify_socket
= open_sock
[1];
886 * Create only one root handle per listener thread for the whole
887 * process lifetime, so we ensure we get ID which is statically
888 * assigned to the root handle.
890 if (sock_info
->root_handle
== -1) {
891 ret
= lttng_abi_create_root_handle();
893 ERR("Error creating root handle");
896 sock_info
->root_handle
= ret
;
899 ret
= register_to_sessiond(sock_info
->socket
, USTCTL_SOCKET_CMD
);
901 ERR("Error registering to %s ust cmd socket",
903 prev_connect_failed
= 1;
905 * If we cannot register to the sessiond daemon, don't
906 * delay constructor execution.
908 ret
= handle_register_done(sock_info
);
913 ret
= register_to_sessiond(sock_info
->notify_socket
,
914 USTCTL_SOCKET_NOTIFY
);
916 ERR("Error registering to %s ust notify socket",
918 prev_connect_failed
= 1;
920 * If we cannot register to the sessiond daemon, don't
921 * delay constructor execution.
923 ret
= handle_register_done(sock_info
);
928 sock
= sock_info
->socket
;
934 struct ustcomm_ust_msg lum
;
936 len
= ustcomm_recv_unix_sock(sock
, &lum
, sizeof(lum
));
938 case 0: /* orderly shutdown */
939 DBG("%s lttng-sessiond has performed an orderly shutdown", sock_info
->name
);
941 if (lttng_ust_comm_should_quit
) {
945 * Either sessiond has shutdown or refused us by closing the socket.
946 * In either case, we don't want to delay construction execution,
947 * and we need to wait before retry.
949 prev_connect_failed
= 1;
951 * If we cannot register to the sessiond daemon, don't
952 * delay constructor execution.
954 ret
= handle_register_done(sock_info
);
959 print_cmd(lum
.cmd
, lum
.handle
);
960 ret
= handle_message(sock_info
, sock
, &lum
);
962 ERR("Error handling message for %s socket", sock_info
->name
);
967 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len
);
969 DBG("incorrect message size (%s socket): %zd", sock_info
->name
, len
);
971 if (len
== -ECONNRESET
) {
972 DBG("%s remote end closed connection", sock_info
->name
);
981 if (lttng_ust_comm_should_quit
) {
984 /* Cleanup socket handles before trying to reconnect */
985 lttng_ust_objd_table_owner_cleanup(sock_info
);
987 goto restart
; /* try to reconnect */
990 sock_info
->thread_active
= 0;
996 * Return values: -1: don't wait. 0: wait forever. 1: timeout wait.
999 int get_timeout(struct timespec
*constructor_timeout
)
1001 long constructor_delay_ms
= LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS
;
1005 str_delay
= getenv("LTTNG_UST_REGISTER_TIMEOUT");
1007 constructor_delay_ms
= strtol(str_delay
, NULL
, 10);
1010 switch (constructor_delay_ms
) {
1011 case -1:/* fall-through */
1013 return constructor_delay_ms
;
1019 * If we are unable to find the current time, don't wait.
1021 ret
= clock_gettime(CLOCK_REALTIME
, constructor_timeout
);
1025 constructor_timeout
->tv_sec
+= constructor_delay_ms
/ 1000UL;
1026 constructor_timeout
->tv_nsec
+=
1027 (constructor_delay_ms
% 1000UL) * 1000000UL;
1028 if (constructor_timeout
->tv_nsec
>= 1000000000UL) {
1029 constructor_timeout
->tv_sec
++;
1030 constructor_timeout
->tv_nsec
-= 1000000000UL;
1036 * sessiond monitoring thread: monitor presence of global and per-user
1037 * sessiond by polling the application common named pipe.
1039 void __attribute__((constructor
)) lttng_ust_init(void)
1041 struct timespec constructor_timeout
;
1042 sigset_t sig_all_blocked
, orig_parent_mask
;
1043 pthread_attr_t thread_attr
;
1047 if (uatomic_xchg(&initialized
, 1) == 1)
1051 * Fixup interdependency between TLS fixup mutex (which happens
1052 * to be the dynamic linker mutex) and ust_lock, taken within
1055 lttng_fixup_ringbuffer_tls();
1056 lttng_fixup_vtid_tls();
1057 lttng_fixup_nest_count_tls();
1058 lttng_fixup_procname_tls();
1061 * We want precise control over the order in which we construct
1062 * our sub-libraries vs starting to receive commands from
1063 * sessiond (otherwise leading to errors when trying to create
1064 * sessiond before the init functions are completed).
1068 lttng_ring_buffer_metadata_client_init();
1069 lttng_ring_buffer_client_overwrite_init();
1070 lttng_ring_buffer_client_discard_init();
1072 timeout_mode
= get_timeout(&constructor_timeout
);
1074 ret
= sem_init(&constructor_wait
, 0, 0);
1077 ret
= setup_local_apps();
1079 DBG("local apps setup returned %d", ret
);
1082 /* A new thread created by pthread_create inherits the signal mask
1083 * from the parent. To avoid any signal being received by the
1084 * listener thread, we block all signals temporarily in the parent,
1085 * while we create the listener thread.
1087 sigfillset(&sig_all_blocked
);
1088 ret
= pthread_sigmask(SIG_SETMASK
, &sig_all_blocked
, &orig_parent_mask
);
1090 ERR("pthread_sigmask: %s", strerror(ret
));
1093 ret
= pthread_attr_init(&thread_attr
);
1095 ERR("pthread_attr_init: %s", strerror(ret
));
1097 ret
= pthread_attr_setdetachstate(&thread_attr
, PTHREAD_CREATE_DETACHED
);
1099 ERR("pthread_attr_setdetachstate: %s", strerror(ret
));
1103 ret
= pthread_create(&global_apps
.ust_listener
, &thread_attr
,
1104 ust_listener_thread
, &global_apps
);
1106 ERR("pthread_create global: %s", strerror(ret
));
1108 global_apps
.thread_active
= 1;
1111 if (local_apps
.allowed
) {
1113 ret
= pthread_create(&local_apps
.ust_listener
, &thread_attr
,
1114 ust_listener_thread
, &local_apps
);
1116 ERR("pthread_create local: %s", strerror(ret
));
1118 local_apps
.thread_active
= 1;
1121 handle_register_done(&local_apps
);
1123 ret
= pthread_attr_destroy(&thread_attr
);
1125 ERR("pthread_attr_destroy: %s", strerror(ret
));
1128 /* Restore original signal mask in parent */
1129 ret
= pthread_sigmask(SIG_SETMASK
, &orig_parent_mask
, NULL
);
1131 ERR("pthread_sigmask: %s", strerror(ret
));
1134 switch (timeout_mode
) {
1135 case 1: /* timeout wait */
1137 ret
= sem_timedwait(&constructor_wait
,
1138 &constructor_timeout
);
1139 } while (ret
< 0 && errno
== EINTR
);
1140 if (ret
< 0 && errno
== ETIMEDOUT
) {
1141 ERR("Timed out waiting for lttng-sessiond");
1146 case -1:/* wait forever */
1148 ret
= sem_wait(&constructor_wait
);
1149 } while (ret
< 0 && errno
== EINTR
);
1152 case 0: /* no timeout */
1158 void lttng_ust_cleanup(int exiting
)
1160 cleanup_sock_info(&global_apps
, exiting
);
1161 if (local_apps
.allowed
) {
1162 cleanup_sock_info(&local_apps
, exiting
);
1165 * The teardown in this function all affect data structures
1166 * accessed under the UST lock by the listener thread. This
1167 * lock, along with the lttng_ust_comm_should_quit flag, ensure
1168 * that none of these threads are accessing this data at this
1171 lttng_ust_abi_exit();
1172 lttng_ust_events_exit();
1173 lttng_ring_buffer_client_discard_exit();
1174 lttng_ring_buffer_client_overwrite_exit();
1175 lttng_ring_buffer_metadata_client_exit();
1178 /* Reinitialize values for fork */
1180 lttng_ust_comm_should_quit
= 0;
1185 void __attribute__((destructor
)) lttng_ust_exit(void)
1190 * Using pthread_cancel here because:
1191 * A) we don't want to hang application teardown.
1192 * B) the thread is not allocating any resource.
1196 * Require the communication thread to quit. Synchronize with
1197 * mutexes to ensure it is not in a mutex critical section when
1198 * pthread_cancel is later called.
1201 lttng_ust_comm_should_quit
= 1;
1203 /* cancel threads */
1204 if (global_apps
.thread_active
) {
1205 ret
= pthread_cancel(global_apps
.ust_listener
);
1207 ERR("Error cancelling global ust listener thread: %s",
1210 global_apps
.thread_active
= 0;
1213 if (local_apps
.thread_active
) {
1214 ret
= pthread_cancel(local_apps
.ust_listener
);
1216 ERR("Error cancelling local ust listener thread: %s",
1219 local_apps
.thread_active
= 0;
1225 * Do NOT join threads: use of sys_futex makes it impossible to
1226 * join the threads without using async-cancel, but async-cancel
1227 * is delivered by a signal, which could hit the target thread
1228 * anywhere in its code path, including while the ust_lock() is
1229 * held, causing a deadlock for the other thread. Let the OS
1230 * cleanup the threads if there are stalled in a syscall.
1232 lttng_ust_cleanup(1);
1236 * We exclude the worker threads across fork and clone (except
1237 * CLONE_VM), because these system calls only keep the forking thread
1238 * running in the child. Therefore, we don't want to call fork or clone
1239 * in the middle of an tracepoint or ust tracing state modification.
1240 * Holding this mutex protects these structures across fork and clone.
1242 void ust_before_fork(sigset_t
*save_sigset
)
1245 * Disable signals. This is to avoid that the child intervenes
1246 * before it is properly setup for tracing. It is safer to
1247 * disable all signals, because then we know we are not breaking
1248 * anything by restoring the original mask.
1253 if (URCU_TLS(lttng_ust_nest_count
))
1255 /* Disable signals */
1256 sigfillset(&all_sigs
);
1257 ret
= sigprocmask(SIG_BLOCK
, &all_sigs
, save_sigset
);
1259 PERROR("sigprocmask");
1262 rcu_bp_before_fork();
1265 static void ust_after_fork_common(sigset_t
*restore_sigset
)
1269 DBG("process %d", getpid());
1271 /* Restore signals */
1272 ret
= sigprocmask(SIG_SETMASK
, restore_sigset
, NULL
);
1274 PERROR("sigprocmask");
1278 void ust_after_fork_parent(sigset_t
*restore_sigset
)
1280 if (URCU_TLS(lttng_ust_nest_count
))
1282 DBG("process %d", getpid());
1283 rcu_bp_after_fork_parent();
1284 /* Release mutexes and reenable signals */
1285 ust_after_fork_common(restore_sigset
);
1289 * After fork, in the child, we need to cleanup all the leftover state,
1290 * except the worker thread which already magically disappeared thanks
1291 * to the weird Linux fork semantics. After tyding up, we call
1292 * lttng_ust_init() again to start over as a new PID.
1294 * This is meant for forks() that have tracing in the child between the
1295 * fork and following exec call (if there is any).
1297 void ust_after_fork_child(sigset_t
*restore_sigset
)
1299 if (URCU_TLS(lttng_ust_nest_count
))
1301 DBG("process %d", getpid());
1302 /* Release urcu mutexes */
1303 rcu_bp_after_fork_child();
1304 lttng_ust_cleanup(0);
1305 lttng_context_vtid_reset();
1306 /* Release mutexes and reenable signals */
1307 ust_after_fork_common(restore_sigset
);