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>
45 #include <usterr-signal-safe.h>
46 #include "tracepoint-internal.h"
47 #include "ltt-tracer-core.h"
49 #include "../libringbuffer/tlsfixup.h"
52 * Has lttng ust comm constructor been called ?
54 static int initialized
;
57 * The ust_lock/ust_unlock lock is used as a communication thread mutex.
58 * Held when handling a command, also held by fork() to deal with
59 * removal of threads, and by exit path.
62 /* Should the ust comm thread quit ? */
63 static int lttng_ust_comm_should_quit
;
66 * Wait for either of these before continuing to the main
68 * - the register_done message from sessiond daemon
69 * (will let the sessiond daemon enable sessions before main
71 * - sessiond daemon is not reachable.
72 * - timeout (ensuring applications are resilient to session
75 static sem_t constructor_wait
;
77 * Doing this for both the global and local sessiond.
79 static int sem_count
= { 2 };
82 * Counting nesting within lttng-ust. Used to ensure that calling fork()
83 * from liblttng-ust does not execute the pre/post fork handlers.
85 static int __thread lttng_ust_nest_count
;
88 * Info about socket and associated listener thread.
92 pthread_t ust_listener
; /* listener thread */
94 int constructor_sem_posted
;
98 char sock_path
[PATH_MAX
];
101 char wait_shm_path
[PATH_MAX
];
105 /* Socket from app (connect) to session daemon (listen) for communication */
106 struct sock_info global_apps
= {
113 .sock_path
= DEFAULT_GLOBAL_APPS_UNIX_SOCK
,
116 .wait_shm_path
= DEFAULT_GLOBAL_APPS_WAIT_SHM_PATH
,
119 /* TODO: allow global_apps_sock_path override */
121 struct sock_info local_apps
= {
125 .allowed
= 0, /* Check setuid bit first */
130 static int wait_poll_fallback
;
132 extern void ltt_ring_buffer_client_overwrite_init(void);
133 extern void ltt_ring_buffer_client_discard_init(void);
134 extern void ltt_ring_buffer_metadata_client_init(void);
135 extern void ltt_ring_buffer_client_overwrite_exit(void);
136 extern void ltt_ring_buffer_client_discard_exit(void);
137 extern void ltt_ring_buffer_metadata_client_exit(void);
140 int setup_local_apps(void)
142 const char *home_dir
;
147 * Disallow per-user tracing for setuid binaries.
149 if (uid
!= geteuid()) {
150 local_apps
.allowed
= 0;
153 local_apps
.allowed
= 1;
155 home_dir
= (const char *) getenv("HOME");
158 snprintf(local_apps
.sock_path
, PATH_MAX
,
159 DEFAULT_HOME_APPS_UNIX_SOCK
, home_dir
);
160 snprintf(local_apps
.wait_shm_path
, PATH_MAX
,
161 DEFAULT_HOME_APPS_WAIT_SHM_PATH
, uid
);
166 int register_app_to_sessiond(int socket
)
176 uint32_t bits_per_long
;
177 char name
[16]; /* process name */
180 reg_msg
.major
= LTTNG_UST_COMM_VERSION_MAJOR
;
181 reg_msg
.minor
= LTTNG_UST_COMM_VERSION_MINOR
;
182 reg_msg
.pid
= getpid();
183 reg_msg
.ppid
= getppid();
184 reg_msg
.uid
= getuid();
185 reg_msg
.gid
= getgid();
186 reg_msg
.bits_per_long
= CAA_BITS_PER_LONG
;
187 lttng_ust_getprocname(reg_msg
.name
);
189 ret
= ustcomm_send_unix_sock(socket
, ®_msg
, sizeof(reg_msg
));
190 if (ret
>= 0 && ret
!= sizeof(reg_msg
))
196 int send_reply(int sock
, struct ustcomm_ust_reply
*lur
)
200 len
= ustcomm_send_unix_sock(sock
, lur
, sizeof(*lur
));
203 DBG("message successfully sent");
206 if (errno
== ECONNRESET
) {
207 printf("remote end closed connection\n");
212 printf("incorrect message size: %zd\n", len
);
218 int handle_register_done(struct sock_info
*sock_info
)
222 if (sock_info
->constructor_sem_posted
)
224 sock_info
->constructor_sem_posted
= 1;
225 if (uatomic_read(&sem_count
) <= 0) {
228 ret
= uatomic_add_return(&sem_count
, -1);
230 ret
= sem_post(&constructor_wait
);
237 int handle_message(struct sock_info
*sock_info
,
238 int sock
, struct ustcomm_ust_msg
*lum
)
241 const struct lttng_ust_objd_ops
*ops
;
242 struct ustcomm_ust_reply lur
;
249 memset(&lur
, 0, sizeof(lur
));
251 if (lttng_ust_comm_should_quit
) {
256 ops
= objd_ops(lum
->handle
);
263 case LTTNG_UST_REGISTER_DONE
:
264 if (lum
->handle
== LTTNG_UST_ROOT_HANDLE
)
265 ret
= handle_register_done(sock_info
);
269 case LTTNG_UST_RELEASE
:
270 if (lum
->handle
== LTTNG_UST_ROOT_HANDLE
)
273 ret
= lttng_ust_objd_unref(lum
->handle
);
277 ret
= ops
->cmd(lum
->handle
, lum
->cmd
,
278 (unsigned long) &lum
->u
,
286 lur
.handle
= lum
->handle
;
290 lur
.ret_code
= USTCOMM_OK
;
292 //lur.ret_code = USTCOMM_SESSION_FAIL;
297 case LTTNG_UST_STREAM
:
299 * Special-case reply to send stream info.
302 lur
.u
.stream
.memory_map_size
= *args
.stream
.memory_map_size
;
303 shm_fd
= *args
.stream
.shm_fd
;
304 wait_fd
= *args
.stream
.wait_fd
;
306 case LTTNG_UST_METADATA
:
307 case LTTNG_UST_CHANNEL
:
308 lur
.u
.channel
.memory_map_size
= *args
.channel
.memory_map_size
;
309 shm_fd
= *args
.channel
.shm_fd
;
310 wait_fd
= *args
.channel
.wait_fd
;
312 case LTTNG_UST_TRACER_VERSION
:
313 lur
.u
.version
= lum
->u
.version
;
315 case LTTNG_UST_TRACEPOINT_LIST_GET
:
316 memcpy(&lur
.u
.tracepoint
, &lum
->u
.tracepoint
, sizeof(lur
.u
.tracepoint
));
320 ret
= send_reply(sock
, &lur
);
322 perror("error sending reply");
326 if ((lum
->cmd
== LTTNG_UST_STREAM
327 || lum
->cmd
== LTTNG_UST_CHANNEL
328 || lum
->cmd
== LTTNG_UST_METADATA
)
329 && lur
.ret_code
== USTCOMM_OK
) {
332 /* we also need to send the file descriptors. */
333 ret
= ustcomm_send_fds_unix_sock(sock
,
337 perror("send shm_fd");
341 * The sessiond expects 2 file descriptors, even upon
344 ret
= ustcomm_send_fds_unix_sock(sock
,
348 perror("send wait_fd");
357 * LTTNG_UST_TRACEPOINT_FIELD_LIST_GET needs to send the field
360 if (lur
.ret_code
== USTCOMM_OK
) {
362 case LTTNG_UST_TRACEPOINT_FIELD_LIST_GET
:
363 len
= ustcomm_send_unix_sock(sock
,
364 &args
.field_list
.entry
,
365 sizeof(args
.field_list
.entry
));
366 if (len
!= sizeof(args
.field_list
.entry
)) {
373 * We still have the memory map reference, and the fds have been
374 * sent to the sessiond. We can therefore close those fds. Note
375 * that we keep the write side of the wait_fd open, but close
378 if (lur
.ret_code
== USTCOMM_OK
) {
380 case LTTNG_UST_STREAM
:
384 PERROR("Error closing stream shm_fd");
386 *args
.stream
.shm_fd
= -1;
389 ret
= close(wait_fd
);
391 PERROR("Error closing stream wait_fd");
393 *args
.stream
.wait_fd
= -1;
396 case LTTNG_UST_METADATA
:
397 case LTTNG_UST_CHANNEL
:
401 PERROR("Error closing channel shm_fd");
403 *args
.channel
.shm_fd
= -1;
406 ret
= close(wait_fd
);
408 PERROR("Error closing channel wait_fd");
410 *args
.channel
.wait_fd
= -1;
422 void cleanup_sock_info(struct sock_info
*sock_info
, int exiting
)
426 if (sock_info
->socket
!= -1) {
427 ret
= ustcomm_close_unix_sock(sock_info
->socket
);
429 ERR("Error closing apps socket");
431 sock_info
->socket
= -1;
433 if (sock_info
->root_handle
!= -1) {
434 ret
= lttng_ust_objd_unref(sock_info
->root_handle
);
436 ERR("Error unref root handle");
438 sock_info
->root_handle
= -1;
440 sock_info
->constructor_sem_posted
= 0;
442 * wait_shm_mmap is used by listener threads outside of the
443 * ust lock, so we cannot tear it down ourselves, because we
444 * cannot join on these threads. Leave this task to the OS
447 if (!exiting
&& sock_info
->wait_shm_mmap
) {
448 ret
= munmap(sock_info
->wait_shm_mmap
, sysconf(_SC_PAGE_SIZE
));
450 ERR("Error unmapping wait shm");
452 sock_info
->wait_shm_mmap
= NULL
;
457 * Using fork to set umask in the child process (not multi-thread safe).
458 * We deal with the shm_open vs ftruncate race (happening when the
459 * sessiond owns the shm and does not let everybody modify it, to ensure
460 * safety against shm_unlink) by simply letting the mmap fail and
461 * retrying after a few seconds.
462 * For global shm, everybody has rw access to it until the sessiond
466 int get_wait_shm(struct sock_info
*sock_info
, size_t mmap_size
)
468 int wait_shm_fd
, ret
;
472 * Try to open read-only.
474 wait_shm_fd
= shm_open(sock_info
->wait_shm_path
, O_RDONLY
, 0);
475 if (wait_shm_fd
>= 0) {
477 } else if (wait_shm_fd
< 0 && errno
!= ENOENT
) {
479 * Real-only open did not work, and it's not because the
480 * entry was not present. It's a failure that prohibits
483 ERR("Error opening shm %s", sock_info
->wait_shm_path
);
487 * If the open failed because the file did not exist, try
488 * creating it ourself.
490 lttng_ust_nest_count
++;
492 lttng_ust_nest_count
--;
497 * Parent: wait for child to return, in which case the
498 * shared memory map will have been created.
501 if (pid
< 0 || !WIFEXITED(status
) || WEXITSTATUS(status
) != 0) {
506 * Try to open read-only again after creation.
508 wait_shm_fd
= shm_open(sock_info
->wait_shm_path
, O_RDONLY
, 0);
509 if (wait_shm_fd
< 0) {
511 * Real-only open did not work. It's a failure
512 * that prohibits using shm.
514 ERR("Error opening shm %s", sock_info
->wait_shm_path
);
518 } else if (pid
== 0) {
522 create_mode
= S_IRUSR
| S_IWUSR
| S_IRGRP
;
523 if (sock_info
->global
)
524 create_mode
|= S_IROTH
| S_IWGRP
| S_IWOTH
;
526 * We're alone in a child process, so we can modify the
527 * process-wide umask.
531 * Try creating shm (or get rw access).
532 * We don't do an exclusive open, because we allow other
533 * processes to create+ftruncate it concurrently.
535 wait_shm_fd
= shm_open(sock_info
->wait_shm_path
,
536 O_RDWR
| O_CREAT
, create_mode
);
537 if (wait_shm_fd
>= 0) {
538 ret
= ftruncate(wait_shm_fd
, mmap_size
);
546 * For local shm, we need to have rw access to accept
547 * opening it: this means the local sessiond will be
548 * able to wake us up. For global shm, we open it even
549 * if rw access is not granted, because the root.root
550 * sessiond will be able to override all rights and wake
553 if (!sock_info
->global
&& errno
!= EACCES
) {
554 ERR("Error opening shm %s", sock_info
->wait_shm_path
);
558 * The shm exists, but we cannot open it RW. Report
566 if (wait_shm_fd
>= 0 && !sock_info
->global
) {
570 * Ensure that our user is the owner of the shm file for
571 * local shm. If we do not own the file, it means our
572 * sessiond will not have access to wake us up (there is
573 * probably a rogue process trying to fake our
574 * sessiond). Fallback to polling method in this case.
576 ret
= fstat(wait_shm_fd
, &statbuf
);
581 if (statbuf
.st_uid
!= getuid())
587 ret
= close(wait_shm_fd
);
589 PERROR("Error closing fd");
595 char *get_map_shm(struct sock_info
*sock_info
)
597 size_t mmap_size
= sysconf(_SC_PAGE_SIZE
);
598 int wait_shm_fd
, ret
;
601 wait_shm_fd
= get_wait_shm(sock_info
, mmap_size
);
602 if (wait_shm_fd
< 0) {
605 wait_shm_mmap
= mmap(NULL
, mmap_size
, PROT_READ
,
606 MAP_SHARED
, wait_shm_fd
, 0);
607 /* close shm fd immediately after taking the mmap reference */
608 ret
= close(wait_shm_fd
);
610 PERROR("Error closing fd");
612 if (wait_shm_mmap
== MAP_FAILED
) {
613 DBG("mmap error (can be caused by race with sessiond). Fallback to poll mode.");
616 return wait_shm_mmap
;
623 void wait_for_sessiond(struct sock_info
*sock_info
)
628 if (lttng_ust_comm_should_quit
) {
631 if (wait_poll_fallback
) {
634 if (!sock_info
->wait_shm_mmap
) {
635 sock_info
->wait_shm_mmap
= get_map_shm(sock_info
);
636 if (!sock_info
->wait_shm_mmap
)
641 DBG("Waiting for %s apps sessiond", sock_info
->name
);
642 /* Wait for futex wakeup */
643 if (uatomic_read((int32_t *) sock_info
->wait_shm_mmap
) == 0) {
644 ret
= futex_async((int32_t *) sock_info
->wait_shm_mmap
,
645 FUTEX_WAIT
, 0, NULL
, NULL
, 0);
647 if (errno
== EFAULT
) {
648 wait_poll_fallback
= 1;
650 "Linux kernels 2.6.33 to 3.0 (with the exception of stable versions) "
651 "do not support FUTEX_WAKE on read-only memory mappings correctly. "
652 "Please upgrade your kernel "
653 "(fix is commit 9ea71503a8ed9184d2d0b8ccc4d269d05f7940ae in Linux kernel "
654 "mainline). LTTng-UST will use polling mode fallback.");
672 * This thread does not allocate any resource, except within
673 * handle_message, within mutex protection. This mutex protects against
675 * The other moment it allocates resources is at socket connexion, which
676 * is also protected by the mutex.
679 void *ust_listener_thread(void *arg
)
681 struct sock_info
*sock_info
= arg
;
682 int sock
, ret
, prev_connect_failed
= 0, has_waited
= 0;
684 /* Restart trying to connect to the session daemon */
686 if (prev_connect_failed
) {
687 /* Wait for sessiond availability with pipe */
688 wait_for_sessiond(sock_info
);
692 * Sleep for 5 seconds before retrying after a
693 * sequence of failure / wait / failure. This
694 * deals with a killed or broken session daemon.
699 prev_connect_failed
= 0;
703 if (lttng_ust_comm_should_quit
) {
708 if (sock_info
->socket
!= -1) {
709 ret
= ustcomm_close_unix_sock(sock_info
->socket
);
711 ERR("Error closing %s apps socket", sock_info
->name
);
713 sock_info
->socket
= -1;
717 ret
= ustcomm_connect_unix_sock(sock_info
->sock_path
);
719 DBG("Info: sessiond not accepting connections to %s apps socket", sock_info
->name
);
720 prev_connect_failed
= 1;
722 * If we cannot find the sessiond daemon, don't delay
723 * constructor execution.
725 ret
= handle_register_done(sock_info
);
731 sock_info
->socket
= sock
= ret
;
734 * Create only one root handle per listener thread for the whole
737 if (sock_info
->root_handle
== -1) {
738 ret
= lttng_abi_create_root_handle();
740 ERR("Error creating root handle");
744 sock_info
->root_handle
= ret
;
747 ret
= register_app_to_sessiond(sock
);
749 ERR("Error registering to %s apps socket", sock_info
->name
);
750 prev_connect_failed
= 1;
752 * If we cannot register to the sessiond daemon, don't
753 * delay constructor execution.
755 ret
= handle_register_done(sock_info
);
764 struct ustcomm_ust_msg lum
;
766 len
= ustcomm_recv_unix_sock(sock
, &lum
, sizeof(lum
));
768 case 0: /* orderly shutdown */
769 DBG("%s ltt-sessiond has performed an orderly shutdown\n", sock_info
->name
);
772 * Either sessiond has shutdown or refused us by closing the socket.
773 * In either case, we don't want to delay construction execution,
774 * and we need to wait before retry.
776 prev_connect_failed
= 1;
778 * If we cannot register to the sessiond daemon, don't
779 * delay constructor execution.
781 ret
= handle_register_done(sock_info
);
786 DBG("message received\n");
787 ret
= handle_message(sock_info
, sock
, &lum
);
789 ERR("Error handling message for %s socket", sock_info
->name
);
793 DBG("Receive failed from lttng-sessiond with errno %d", errno
);
794 if (errno
== ECONNRESET
) {
795 ERR("%s remote end closed connection\n", sock_info
->name
);
800 ERR("incorrect message size (%s socket): %zd\n", sock_info
->name
, len
);
806 goto restart
; /* try to reconnect */
812 * Return values: -1: don't wait. 0: wait forever. 1: timeout wait.
815 int get_timeout(struct timespec
*constructor_timeout
)
817 long constructor_delay_ms
= LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS
;
821 str_delay
= getenv("LTTNG_UST_REGISTER_TIMEOUT");
823 constructor_delay_ms
= strtol(str_delay
, NULL
, 10);
826 switch (constructor_delay_ms
) {
827 case -1:/* fall-through */
829 return constructor_delay_ms
;
835 * If we are unable to find the current time, don't wait.
837 ret
= clock_gettime(CLOCK_REALTIME
, constructor_timeout
);
841 constructor_timeout
->tv_sec
+= constructor_delay_ms
/ 1000UL;
842 constructor_timeout
->tv_nsec
+=
843 (constructor_delay_ms
% 1000UL) * 1000000UL;
844 if (constructor_timeout
->tv_nsec
>= 1000000000UL) {
845 constructor_timeout
->tv_sec
++;
846 constructor_timeout
->tv_nsec
-= 1000000000UL;
852 * sessiond monitoring thread: monitor presence of global and per-user
853 * sessiond by polling the application common named pipe.
857 void __attribute__((constructor
)) lttng_ust_init(void)
859 struct timespec constructor_timeout
;
860 sigset_t sig_all_blocked
, orig_parent_mask
;
864 if (uatomic_xchg(&initialized
, 1) == 1)
868 * Fixup interdependency between TLS fixup mutex (which happens
869 * to be the dynamic linker mutex) and ust_lock, taken within
872 lttng_fixup_event_tls();
873 lttng_fixup_ringbuffer_tls();
874 lttng_fixup_vtid_tls();
877 * We want precise control over the order in which we construct
878 * our sub-libraries vs starting to receive commands from
879 * sessiond (otherwise leading to errors when trying to create
880 * sessiond before the init functions are completed).
884 ltt_ring_buffer_metadata_client_init();
885 ltt_ring_buffer_client_overwrite_init();
886 ltt_ring_buffer_client_discard_init();
888 timeout_mode
= get_timeout(&constructor_timeout
);
890 ret
= sem_init(&constructor_wait
, 0, 0);
893 ret
= setup_local_apps();
895 ERR("Error setting up to local apps");
898 /* A new thread created by pthread_create inherits the signal mask
899 * from the parent. To avoid any signal being received by the
900 * listener thread, we block all signals temporarily in the parent,
901 * while we create the listener thread.
903 sigfillset(&sig_all_blocked
);
904 ret
= pthread_sigmask(SIG_SETMASK
, &sig_all_blocked
, &orig_parent_mask
);
906 ERR("pthread_sigmask: %s", strerror(ret
));
909 ret
= pthread_create(&global_apps
.ust_listener
, NULL
,
910 ust_listener_thread
, &global_apps
);
912 ERR("pthread_create global: %s", strerror(ret
));
914 if (local_apps
.allowed
) {
915 ret
= pthread_create(&local_apps
.ust_listener
, NULL
,
916 ust_listener_thread
, &local_apps
);
918 ERR("pthread_create local: %s", strerror(ret
));
921 handle_register_done(&local_apps
);
924 /* Restore original signal mask in parent */
925 ret
= pthread_sigmask(SIG_SETMASK
, &orig_parent_mask
, NULL
);
927 ERR("pthread_sigmask: %s", strerror(ret
));
930 switch (timeout_mode
) {
931 case 1: /* timeout wait */
933 ret
= sem_timedwait(&constructor_wait
,
934 &constructor_timeout
);
935 } while (ret
< 0 && errno
== EINTR
);
936 if (ret
< 0 && errno
== ETIMEDOUT
) {
937 ERR("Timed out waiting for ltt-sessiond");
942 case -1:/* wait forever */
944 ret
= sem_wait(&constructor_wait
);
945 } while (ret
< 0 && errno
== EINTR
);
948 case 0: /* no timeout */
954 void lttng_ust_cleanup(int exiting
)
956 cleanup_sock_info(&global_apps
, exiting
);
957 if (local_apps
.allowed
) {
958 cleanup_sock_info(&local_apps
, exiting
);
961 * The teardown in this function all affect data structures
962 * accessed under the UST lock by the listener thread. This
963 * lock, along with the lttng_ust_comm_should_quit flag, ensure
964 * that none of these threads are accessing this data at this
967 lttng_ust_abi_exit();
968 lttng_ust_events_exit();
969 ltt_ring_buffer_client_discard_exit();
970 ltt_ring_buffer_client_overwrite_exit();
971 ltt_ring_buffer_metadata_client_exit();
974 /* Reinitialize values for fork */
976 lttng_ust_comm_should_quit
= 0;
981 void __attribute__((destructor
)) lttng_ust_exit(void)
986 * Using pthread_cancel here because:
987 * A) we don't want to hang application teardown.
988 * B) the thread is not allocating any resource.
992 * Require the communication thread to quit. Synchronize with
993 * mutexes to ensure it is not in a mutex critical section when
994 * pthread_cancel is later called.
997 lttng_ust_comm_should_quit
= 1;
1000 /* cancel threads */
1001 ret
= pthread_cancel(global_apps
.ust_listener
);
1003 ERR("Error cancelling global ust listener thread: %s",
1006 if (local_apps
.allowed
) {
1007 ret
= pthread_cancel(local_apps
.ust_listener
);
1009 ERR("Error cancelling local ust listener thread: %s",
1014 * Do NOT join threads: use of sys_futex makes it impossible to
1015 * join the threads without using async-cancel, but async-cancel
1016 * is delivered by a signal, which could hit the target thread
1017 * anywhere in its code path, including while the ust_lock() is
1018 * held, causing a deadlock for the other thread. Let the OS
1019 * cleanup the threads if there are stalled in a syscall.
1021 lttng_ust_cleanup(1);
1025 * We exclude the worker threads across fork and clone (except
1026 * CLONE_VM), because these system calls only keep the forking thread
1027 * running in the child. Therefore, we don't want to call fork or clone
1028 * in the middle of an tracepoint or ust tracing state modification.
1029 * Holding this mutex protects these structures across fork and clone.
1031 void ust_before_fork(sigset_t
*save_sigset
)
1034 * Disable signals. This is to avoid that the child intervenes
1035 * before it is properly setup for tracing. It is safer to
1036 * disable all signals, because then we know we are not breaking
1037 * anything by restoring the original mask.
1042 if (lttng_ust_nest_count
)
1044 /* Disable signals */
1045 sigfillset(&all_sigs
);
1046 ret
= sigprocmask(SIG_BLOCK
, &all_sigs
, save_sigset
);
1048 PERROR("sigprocmask");
1051 rcu_bp_before_fork();
1054 static void ust_after_fork_common(sigset_t
*restore_sigset
)
1058 DBG("process %d", getpid());
1060 /* Restore signals */
1061 ret
= sigprocmask(SIG_SETMASK
, restore_sigset
, NULL
);
1063 PERROR("sigprocmask");
1067 void ust_after_fork_parent(sigset_t
*restore_sigset
)
1069 if (lttng_ust_nest_count
)
1071 DBG("process %d", getpid());
1072 rcu_bp_after_fork_parent();
1073 /* Release mutexes and reenable signals */
1074 ust_after_fork_common(restore_sigset
);
1078 * After fork, in the child, we need to cleanup all the leftover state,
1079 * except the worker thread which already magically disappeared thanks
1080 * to the weird Linux fork semantics. After tyding up, we call
1081 * lttng_ust_init() again to start over as a new PID.
1083 * This is meant for forks() that have tracing in the child between the
1084 * fork and following exec call (if there is any).
1086 void ust_after_fork_child(sigset_t
*restore_sigset
)
1088 if (lttng_ust_nest_count
)
1090 DBG("process %d", getpid());
1091 /* Release urcu mutexes */
1092 rcu_bp_after_fork_child();
1093 lttng_ust_cleanup(0);
1094 lttng_context_vtid_reset();
1095 /* Release mutexes and reenable signals */
1096 ust_after_fork_common(restore_sigset
);