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>
25 #include <sys/prctl.h>
28 #include <sys/types.h>
34 #include <semaphore.h>
38 #include <urcu/uatomic.h>
39 #include <urcu/futex.h>
40 #include <urcu/compiler.h>
42 #include <lttng/ust-events.h>
43 #include <lttng/ust-abi.h>
44 #include <lttng/ust.h>
46 #include <usterr-signal-safe.h>
47 #include "tracepoint-internal.h"
48 #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 * Force a read (imply TLS fixup for dlopen) of TLS variables.
143 void lttng_fixup_nest_count_tls(void)
145 asm volatile ("" : : "m" (lttng_ust_nest_count
));
149 int setup_local_apps(void)
151 const char *home_dir
;
156 * Disallow per-user tracing for setuid binaries.
158 if (uid
!= geteuid()) {
159 local_apps
.allowed
= 0;
162 local_apps
.allowed
= 1;
164 home_dir
= (const char *) getenv("HOME");
167 snprintf(local_apps
.sock_path
, PATH_MAX
,
168 DEFAULT_HOME_APPS_UNIX_SOCK
, home_dir
);
169 snprintf(local_apps
.wait_shm_path
, PATH_MAX
,
170 DEFAULT_HOME_APPS_WAIT_SHM_PATH
, uid
);
175 int register_app_to_sessiond(int socket
)
186 uint32_t bits_per_long
;
187 char name
[16]; /* process name */
190 reg_msg
.major
= LTTNG_UST_COMM_VERSION_MAJOR
;
191 reg_msg
.minor
= LTTNG_UST_COMM_VERSION_MINOR
;
192 reg_msg
.pid
= getpid();
193 reg_msg
.ppid
= getppid();
194 reg_msg
.uid
= getuid();
195 reg_msg
.gid
= getgid();
196 reg_msg
.bits_per_long
= CAA_BITS_PER_LONG
;
197 prctl_ret
= prctl(PR_GET_NAME
, (unsigned long) reg_msg
.name
, 0, 0, 0);
199 ERR("Error executing prctl");
203 ret
= ustcomm_send_unix_sock(socket
, ®_msg
, sizeof(reg_msg
));
204 if (ret
>= 0 && ret
!= sizeof(reg_msg
))
210 int send_reply(int sock
, struct ustcomm_ust_reply
*lur
)
214 len
= ustcomm_send_unix_sock(sock
, lur
, sizeof(*lur
));
217 DBG("message successfully sent");
220 if (errno
== ECONNRESET
) {
221 printf("remote end closed connection\n");
226 printf("incorrect message size: %zd\n", len
);
232 int handle_register_done(struct sock_info
*sock_info
)
236 if (sock_info
->constructor_sem_posted
)
238 sock_info
->constructor_sem_posted
= 1;
239 if (uatomic_read(&sem_count
) <= 0) {
242 ret
= uatomic_add_return(&sem_count
, -1);
244 ret
= sem_post(&constructor_wait
);
251 int handle_message(struct sock_info
*sock_info
,
252 int sock
, struct ustcomm_ust_msg
*lum
)
255 const struct lttng_ust_objd_ops
*ops
;
256 struct ustcomm_ust_reply lur
;
262 memset(&lur
, 0, sizeof(lur
));
264 if (lttng_ust_comm_should_quit
) {
269 ops
= objd_ops(lum
->handle
);
276 case LTTNG_UST_REGISTER_DONE
:
277 if (lum
->handle
== LTTNG_UST_ROOT_HANDLE
)
278 ret
= handle_register_done(sock_info
);
282 case LTTNG_UST_RELEASE
:
283 if (lum
->handle
== LTTNG_UST_ROOT_HANDLE
)
286 ret
= lttng_ust_objd_unref(lum
->handle
);
290 ret
= ops
->cmd(lum
->handle
, lum
->cmd
,
291 (unsigned long) &lum
->u
,
299 lur
.handle
= lum
->handle
;
303 lur
.ret_code
= USTCOMM_OK
;
305 //lur.ret_code = USTCOMM_SESSION_FAIL;
310 case LTTNG_UST_STREAM
:
312 * Special-case reply to send stream info.
315 lur
.u
.stream
.memory_map_size
= *args
.stream
.memory_map_size
;
316 shm_fd
= *args
.stream
.shm_fd
;
317 wait_fd
= *args
.stream
.wait_fd
;
319 case LTTNG_UST_METADATA
:
320 case LTTNG_UST_CHANNEL
:
321 lur
.u
.channel
.memory_map_size
= *args
.channel
.memory_map_size
;
322 shm_fd
= *args
.channel
.shm_fd
;
323 wait_fd
= *args
.channel
.wait_fd
;
325 case LTTNG_UST_TRACER_VERSION
:
326 lur
.u
.version
= lum
->u
.version
;
328 case LTTNG_UST_TRACEPOINT_LIST_GET
:
329 memcpy(&lur
.u
.tracepoint
, &lum
->u
.tracepoint
, sizeof(lur
.u
.tracepoint
));
333 ret
= send_reply(sock
, &lur
);
335 perror("error sending reply");
339 if ((lum
->cmd
== LTTNG_UST_STREAM
340 || lum
->cmd
== LTTNG_UST_CHANNEL
341 || lum
->cmd
== LTTNG_UST_METADATA
)
342 && lur
.ret_code
== USTCOMM_OK
) {
345 /* we also need to send the file descriptors. */
346 ret
= ustcomm_send_fds_unix_sock(sock
,
350 perror("send shm_fd");
354 * The sessiond expects 2 file descriptors, even upon
357 ret
= ustcomm_send_fds_unix_sock(sock
,
361 perror("send wait_fd");
370 * We still have the memory map reference, and the fds have been
371 * sent to the sessiond. We can therefore close those fds. Note
372 * that we keep the write side of the wait_fd open, but close
375 if (lur
.ret_code
== USTCOMM_OK
) {
377 case LTTNG_UST_STREAM
:
381 PERROR("Error closing stream shm_fd");
383 *args
.stream
.shm_fd
= -1;
386 ret
= close(wait_fd
);
388 PERROR("Error closing stream wait_fd");
390 *args
.stream
.wait_fd
= -1;
393 case LTTNG_UST_METADATA
:
394 case LTTNG_UST_CHANNEL
:
398 PERROR("Error closing channel shm_fd");
400 *args
.channel
.shm_fd
= -1;
403 ret
= close(wait_fd
);
405 PERROR("Error closing channel wait_fd");
407 *args
.channel
.wait_fd
= -1;
419 void cleanup_sock_info(struct sock_info
*sock_info
, int exiting
)
423 if (sock_info
->socket
!= -1) {
424 ret
= ustcomm_close_unix_sock(sock_info
->socket
);
426 ERR("Error closing apps socket");
428 sock_info
->socket
= -1;
430 if (sock_info
->root_handle
!= -1) {
431 ret
= lttng_ust_objd_unref(sock_info
->root_handle
);
433 ERR("Error unref root handle");
435 sock_info
->root_handle
= -1;
437 sock_info
->constructor_sem_posted
= 0;
439 * wait_shm_mmap is used by listener threads outside of the
440 * ust lock, so we cannot tear it down ourselves, because we
441 * cannot join on these threads. Leave this task to the OS
444 if (!exiting
&& sock_info
->wait_shm_mmap
) {
445 ret
= munmap(sock_info
->wait_shm_mmap
, sysconf(_SC_PAGE_SIZE
));
447 ERR("Error unmapping wait shm");
449 sock_info
->wait_shm_mmap
= NULL
;
454 * Using fork to set umask in the child process (not multi-thread safe).
455 * We deal with the shm_open vs ftruncate race (happening when the
456 * sessiond owns the shm and does not let everybody modify it, to ensure
457 * safety against shm_unlink) by simply letting the mmap fail and
458 * retrying after a few seconds.
459 * For global shm, everybody has rw access to it until the sessiond
463 int get_wait_shm(struct sock_info
*sock_info
, size_t mmap_size
)
465 int wait_shm_fd
, ret
;
469 * Try to open read-only.
471 wait_shm_fd
= shm_open(sock_info
->wait_shm_path
, O_RDONLY
, 0);
472 if (wait_shm_fd
>= 0) {
474 } else if (wait_shm_fd
< 0 && errno
!= ENOENT
) {
476 * Real-only open did not work, and it's not because the
477 * entry was not present. It's a failure that prohibits
480 ERR("Error opening shm %s", sock_info
->wait_shm_path
);
484 * If the open failed because the file did not exist, try
485 * creating it ourself.
487 lttng_ust_nest_count
++;
489 lttng_ust_nest_count
--;
494 * Parent: wait for child to return, in which case the
495 * shared memory map will have been created.
498 if (pid
< 0 || !WIFEXITED(status
) || WEXITSTATUS(status
) != 0) {
503 * Try to open read-only again after creation.
505 wait_shm_fd
= shm_open(sock_info
->wait_shm_path
, O_RDONLY
, 0);
506 if (wait_shm_fd
< 0) {
508 * Real-only open did not work. It's a failure
509 * that prohibits using shm.
511 ERR("Error opening shm %s", sock_info
->wait_shm_path
);
515 } else if (pid
== 0) {
519 create_mode
= S_IRUSR
| S_IWUSR
| S_IRGRP
;
520 if (sock_info
->global
)
521 create_mode
|= S_IROTH
| S_IWGRP
| S_IWOTH
;
523 * We're alone in a child process, so we can modify the
524 * process-wide umask.
528 * Try creating shm (or get rw access).
529 * We don't do an exclusive open, because we allow other
530 * processes to create+ftruncate it concurrently.
532 wait_shm_fd
= shm_open(sock_info
->wait_shm_path
,
533 O_RDWR
| O_CREAT
, create_mode
);
534 if (wait_shm_fd
>= 0) {
535 ret
= ftruncate(wait_shm_fd
, mmap_size
);
543 * For local shm, we need to have rw access to accept
544 * opening it: this means the local sessiond will be
545 * able to wake us up. For global shm, we open it even
546 * if rw access is not granted, because the root.root
547 * sessiond will be able to override all rights and wake
550 if (!sock_info
->global
&& errno
!= EACCES
) {
551 ERR("Error opening shm %s", sock_info
->wait_shm_path
);
555 * The shm exists, but we cannot open it RW. Report
563 if (wait_shm_fd
>= 0 && !sock_info
->global
) {
567 * Ensure that our user is the owner of the shm file for
568 * local shm. If we do not own the file, it means our
569 * sessiond will not have access to wake us up (there is
570 * probably a rogue process trying to fake our
571 * sessiond). Fallback to polling method in this case.
573 ret
= fstat(wait_shm_fd
, &statbuf
);
578 if (statbuf
.st_uid
!= getuid())
584 ret
= close(wait_shm_fd
);
586 PERROR("Error closing fd");
592 char *get_map_shm(struct sock_info
*sock_info
)
594 size_t mmap_size
= sysconf(_SC_PAGE_SIZE
);
595 int wait_shm_fd
, ret
;
598 wait_shm_fd
= get_wait_shm(sock_info
, mmap_size
);
599 if (wait_shm_fd
< 0) {
602 wait_shm_mmap
= mmap(NULL
, mmap_size
, PROT_READ
,
603 MAP_SHARED
, wait_shm_fd
, 0);
604 /* close shm fd immediately after taking the mmap reference */
605 ret
= close(wait_shm_fd
);
607 PERROR("Error closing fd");
609 if (wait_shm_mmap
== MAP_FAILED
) {
610 DBG("mmap error (can be caused by race with sessiond). Fallback to poll mode.");
613 return wait_shm_mmap
;
620 void wait_for_sessiond(struct sock_info
*sock_info
)
625 if (lttng_ust_comm_should_quit
) {
628 if (wait_poll_fallback
) {
631 if (!sock_info
->wait_shm_mmap
) {
632 sock_info
->wait_shm_mmap
= get_map_shm(sock_info
);
633 if (!sock_info
->wait_shm_mmap
)
638 DBG("Waiting for %s apps sessiond", sock_info
->name
);
639 /* Wait for futex wakeup */
640 if (uatomic_read((int32_t *) sock_info
->wait_shm_mmap
) == 0) {
641 ret
= futex_async((int32_t *) sock_info
->wait_shm_mmap
,
642 FUTEX_WAIT
, 0, NULL
, NULL
, 0);
644 if (errno
== EFAULT
) {
645 wait_poll_fallback
= 1;
647 "Linux kernels 2.6.33 to 3.0 (with the exception of stable versions) "
648 "do not support FUTEX_WAKE on read-only memory mappings correctly. "
649 "Please upgrade your kernel "
650 "(fix is commit 9ea71503a8ed9184d2d0b8ccc4d269d05f7940ae in Linux kernel "
651 "mainline). LTTng-UST will use polling mode fallback.");
669 * This thread does not allocate any resource, except within
670 * handle_message, within mutex protection. This mutex protects against
672 * The other moment it allocates resources is at socket connexion, which
673 * is also protected by the mutex.
676 void *ust_listener_thread(void *arg
)
678 struct sock_info
*sock_info
= arg
;
679 int sock
, ret
, prev_connect_failed
= 0, has_waited
= 0;
681 /* Restart trying to connect to the session daemon */
683 if (prev_connect_failed
) {
684 /* Wait for sessiond availability with pipe */
685 wait_for_sessiond(sock_info
);
689 * Sleep for 5 seconds before retrying after a
690 * sequence of failure / wait / failure. This
691 * deals with a killed or broken session daemon.
696 prev_connect_failed
= 0;
700 if (lttng_ust_comm_should_quit
) {
705 if (sock_info
->socket
!= -1) {
706 ret
= ustcomm_close_unix_sock(sock_info
->socket
);
708 ERR("Error closing %s apps socket", sock_info
->name
);
710 sock_info
->socket
= -1;
714 ret
= ustcomm_connect_unix_sock(sock_info
->sock_path
);
716 DBG("Info: sessiond not accepting connections to %s apps socket", sock_info
->name
);
717 prev_connect_failed
= 1;
719 * If we cannot find the sessiond daemon, don't delay
720 * constructor execution.
722 ret
= handle_register_done(sock_info
);
728 sock_info
->socket
= sock
= ret
;
731 * Create only one root handle per listener thread for the whole
734 if (sock_info
->root_handle
== -1) {
735 ret
= lttng_abi_create_root_handle();
737 ERR("Error creating root handle");
741 sock_info
->root_handle
= ret
;
744 ret
= register_app_to_sessiond(sock
);
746 ERR("Error registering to %s apps socket", sock_info
->name
);
747 prev_connect_failed
= 1;
749 * If we cannot register to the sessiond daemon, don't
750 * delay constructor execution.
752 ret
= handle_register_done(sock_info
);
761 struct ustcomm_ust_msg lum
;
763 len
= ustcomm_recv_unix_sock(sock
, &lum
, sizeof(lum
));
765 case 0: /* orderly shutdown */
766 DBG("%s ltt-sessiond has performed an orderly shutdown\n", sock_info
->name
);
769 * Either sessiond has shutdown or refused us by closing the socket.
770 * In either case, we don't want to delay construction execution,
771 * and we need to wait before retry.
773 prev_connect_failed
= 1;
775 * If we cannot register to the sessiond daemon, don't
776 * delay constructor execution.
778 ret
= handle_register_done(sock_info
);
783 DBG("message received\n");
784 ret
= handle_message(sock_info
, sock
, &lum
);
786 ERR("Error handling message for %s socket", sock_info
->name
);
790 DBG("Receive failed from lttng-sessiond with errno %d", errno
);
791 if (errno
== ECONNRESET
) {
792 ERR("%s remote end closed connection\n", sock_info
->name
);
797 ERR("incorrect message size (%s socket): %zd\n", sock_info
->name
, len
);
803 goto restart
; /* try to reconnect */
809 * Return values: -1: don't wait. 0: wait forever. 1: timeout wait.
812 int get_timeout(struct timespec
*constructor_timeout
)
814 long constructor_delay_ms
= LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS
;
818 str_delay
= getenv("LTTNG_UST_REGISTER_TIMEOUT");
820 constructor_delay_ms
= strtol(str_delay
, NULL
, 10);
823 switch (constructor_delay_ms
) {
824 case -1:/* fall-through */
826 return constructor_delay_ms
;
832 * If we are unable to find the current time, don't wait.
834 ret
= clock_gettime(CLOCK_REALTIME
, constructor_timeout
);
838 constructor_timeout
->tv_sec
+= constructor_delay_ms
/ 1000UL;
839 constructor_timeout
->tv_nsec
+=
840 (constructor_delay_ms
% 1000UL) * 1000000UL;
841 if (constructor_timeout
->tv_nsec
>= 1000000000UL) {
842 constructor_timeout
->tv_sec
++;
843 constructor_timeout
->tv_nsec
-= 1000000000UL;
849 * sessiond monitoring thread: monitor presence of global and per-user
850 * sessiond by polling the application common named pipe.
854 void __attribute__((constructor
)) lttng_ust_init(void)
856 struct timespec constructor_timeout
;
857 sigset_t sig_all_blocked
, orig_parent_mask
;
861 if (uatomic_xchg(&initialized
, 1) == 1)
865 * Fixup interdependency between TLS fixup mutex (which happens
866 * to be the dynamic linker mutex) and ust_lock, taken within
869 lttng_fixup_event_tls();
870 lttng_fixup_ringbuffer_tls();
871 lttng_fixup_vtid_tls();
872 lttng_fixup_nest_count_tls();
875 * We want precise control over the order in which we construct
876 * our sub-libraries vs starting to receive commands from
877 * sessiond (otherwise leading to errors when trying to create
878 * sessiond before the init functions are completed).
882 ltt_ring_buffer_metadata_client_init();
883 ltt_ring_buffer_client_overwrite_init();
884 ltt_ring_buffer_client_discard_init();
886 timeout_mode
= get_timeout(&constructor_timeout
);
888 ret
= sem_init(&constructor_wait
, 0, 0);
891 ret
= setup_local_apps();
893 ERR("Error setting up to local apps");
896 /* A new thread created by pthread_create inherits the signal mask
897 * from the parent. To avoid any signal being received by the
898 * listener thread, we block all signals temporarily in the parent,
899 * while we create the listener thread.
901 sigfillset(&sig_all_blocked
);
902 ret
= pthread_sigmask(SIG_SETMASK
, &sig_all_blocked
, &orig_parent_mask
);
904 ERR("pthread_sigmask: %s", strerror(ret
));
907 ret
= pthread_create(&global_apps
.ust_listener
, NULL
,
908 ust_listener_thread
, &global_apps
);
910 ERR("pthread_create global: %s", strerror(ret
));
912 if (local_apps
.allowed
) {
913 ret
= pthread_create(&local_apps
.ust_listener
, NULL
,
914 ust_listener_thread
, &local_apps
);
916 ERR("pthread_create local: %s", strerror(ret
));
919 handle_register_done(&local_apps
);
922 /* Restore original signal mask in parent */
923 ret
= pthread_sigmask(SIG_SETMASK
, &orig_parent_mask
, NULL
);
925 ERR("pthread_sigmask: %s", strerror(ret
));
928 switch (timeout_mode
) {
929 case 1: /* timeout wait */
931 ret
= sem_timedwait(&constructor_wait
,
932 &constructor_timeout
);
933 } while (ret
< 0 && errno
== EINTR
);
934 if (ret
< 0 && errno
== ETIMEDOUT
) {
935 ERR("Timed out waiting for ltt-sessiond");
940 case -1:/* wait forever */
942 ret
= sem_wait(&constructor_wait
);
943 } while (ret
< 0 && errno
== EINTR
);
946 case 0: /* no timeout */
952 void lttng_ust_cleanup(int exiting
)
954 cleanup_sock_info(&global_apps
, exiting
);
955 if (local_apps
.allowed
) {
956 cleanup_sock_info(&local_apps
, exiting
);
959 * The teardown in this function all affect data structures
960 * accessed under the UST lock by the listener thread. This
961 * lock, along with the lttng_ust_comm_should_quit flag, ensure
962 * that none of these threads are accessing this data at this
965 lttng_ust_abi_exit();
966 lttng_ust_events_exit();
967 ltt_ring_buffer_client_discard_exit();
968 ltt_ring_buffer_client_overwrite_exit();
969 ltt_ring_buffer_metadata_client_exit();
972 /* Reinitialize values for fork */
974 lttng_ust_comm_should_quit
= 0;
979 void __attribute__((destructor
)) lttng_ust_exit(void)
984 * Using pthread_cancel here because:
985 * A) we don't want to hang application teardown.
986 * B) the thread is not allocating any resource.
990 * Require the communication thread to quit. Synchronize with
991 * mutexes to ensure it is not in a mutex critical section when
992 * pthread_cancel is later called.
995 lttng_ust_comm_should_quit
= 1;
999 ret
= pthread_cancel(global_apps
.ust_listener
);
1001 ERR("Error cancelling global ust listener thread: %s",
1004 if (local_apps
.allowed
) {
1005 ret
= pthread_cancel(local_apps
.ust_listener
);
1007 ERR("Error cancelling local ust listener thread: %s",
1012 * Do NOT join threads: use of sys_futex makes it impossible to
1013 * join the threads without using async-cancel, but async-cancel
1014 * is delivered by a signal, which could hit the target thread
1015 * anywhere in its code path, including while the ust_lock() is
1016 * held, causing a deadlock for the other thread. Let the OS
1017 * cleanup the threads if there are stalled in a syscall.
1019 lttng_ust_cleanup(1);
1023 * We exclude the worker threads across fork and clone (except
1024 * CLONE_VM), because these system calls only keep the forking thread
1025 * running in the child. Therefore, we don't want to call fork or clone
1026 * in the middle of an tracepoint or ust tracing state modification.
1027 * Holding this mutex protects these structures across fork and clone.
1029 void ust_before_fork(sigset_t
*save_sigset
)
1032 * Disable signals. This is to avoid that the child intervenes
1033 * before it is properly setup for tracing. It is safer to
1034 * disable all signals, because then we know we are not breaking
1035 * anything by restoring the original mask.
1040 if (lttng_ust_nest_count
)
1042 /* Disable signals */
1043 sigfillset(&all_sigs
);
1044 ret
= sigprocmask(SIG_BLOCK
, &all_sigs
, save_sigset
);
1046 PERROR("sigprocmask");
1049 rcu_bp_before_fork();
1052 static void ust_after_fork_common(sigset_t
*restore_sigset
)
1056 DBG("process %d", getpid());
1058 /* Restore signals */
1059 ret
= sigprocmask(SIG_SETMASK
, restore_sigset
, NULL
);
1061 PERROR("sigprocmask");
1065 void ust_after_fork_parent(sigset_t
*restore_sigset
)
1067 if (lttng_ust_nest_count
)
1069 DBG("process %d", getpid());
1070 rcu_bp_after_fork_parent();
1071 /* Release mutexes and reenable signals */
1072 ust_after_fork_common(restore_sigset
);
1076 * After fork, in the child, we need to cleanup all the leftover state,
1077 * except the worker thread which already magically disappeared thanks
1078 * to the weird Linux fork semantics. After tyding up, we call
1079 * lttng_ust_init() again to start over as a new PID.
1081 * This is meant for forks() that have tracing in the child between the
1082 * fork and following exec call (if there is any).
1084 void ust_after_fork_child(sigset_t
*restore_sigset
)
1086 if (lttng_ust_nest_count
)
1088 DBG("process %d", getpid());
1089 /* Release urcu mutexes */
1090 rcu_bp_after_fork_child();
1091 lttng_ust_cleanup(0);
1092 lttng_context_vtid_reset();
1093 /* Release mutexes and reenable signals */
1094 ust_after_fork_common(restore_sigset
);