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>
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>
45 #include <lttng/ust-error.h>
46 #include <lttng/ust-ctl.h>
47 #include <urcu/tls-compat.h>
49 #include <usterr-signal-safe.h>
51 #include "tracepoint-internal.h"
52 #include "lttng-tracer-core.h"
54 #include "../libringbuffer/tlsfixup.h"
55 #include "lttng-ust-baddr.h"
57 #include "../libringbuffer/getcpu.h"
60 * Has lttng ust comm constructor been called ?
62 static int initialized
;
65 * The ust_lock/ust_unlock lock is used as a communication thread mutex.
66 * Held when handling a command, also held by fork() to deal with
67 * removal of threads, and by exit path.
69 * The UST lock is the centralized mutex across UST tracing control and
72 * ust_exit_mutex must never nest in ust_mutex.
74 * ust_fork_mutex must never nest in ust_mutex.
76 * ust_mutex_nest is a per-thread nesting counter, allowing the perf
77 * counter lazy initialization called by events within the statedump,
78 * which traces while the ust_mutex is held.
80 * ust_lock nests within the dynamic loader lock (within glibc) because
81 * it is taken within the library constructor.
83 static pthread_mutex_t ust_mutex
= PTHREAD_MUTEX_INITIALIZER
;
85 /* Allow nesting the ust_mutex within the same thread. */
86 static DEFINE_URCU_TLS(int, ust_mutex_nest
);
89 * ust_exit_mutex protects thread_active variable wrt thread exit. It
90 * cannot be done by ust_mutex because pthread_cancel(), which takes an
91 * internal libc lock, cannot nest within ust_mutex.
93 * It never nests within a ust_mutex.
95 static pthread_mutex_t ust_exit_mutex
= PTHREAD_MUTEX_INITIALIZER
;
98 * ust_fork_mutex protects base address statedump tracing against forks. It
99 * prevents the dynamic loader lock to be taken (by base address statedump
100 * tracing) while a fork is happening, thus preventing deadlock issues with
101 * the dynamic loader lock.
103 static pthread_mutex_t ust_fork_mutex
= PTHREAD_MUTEX_INITIALIZER
;
105 /* Should the ust comm thread quit ? */
106 static int lttng_ust_comm_should_quit
;
109 * Return 0 on success, -1 if should quit.
110 * The lock is taken in both cases.
115 sigset_t sig_all_blocked
, orig_mask
;
118 sigfillset(&sig_all_blocked
);
119 ret
= pthread_sigmask(SIG_SETMASK
, &sig_all_blocked
, &orig_mask
);
121 ERR("pthread_sigmask: %s", strerror(ret
));
123 if (!URCU_TLS(ust_mutex_nest
)++)
124 pthread_mutex_lock(&ust_mutex
);
125 ret
= pthread_sigmask(SIG_SETMASK
, &orig_mask
, NULL
);
127 ERR("pthread_sigmask: %s", strerror(ret
));
129 if (lttng_ust_comm_should_quit
) {
137 * ust_lock_nocheck() can be used in constructors/destructors, because
138 * they are already nested within the dynamic loader lock, and therefore
139 * have exclusive access against execution of liblttng-ust destructor.
142 void ust_lock_nocheck(void)
144 sigset_t sig_all_blocked
, orig_mask
;
147 sigfillset(&sig_all_blocked
);
148 ret
= pthread_sigmask(SIG_SETMASK
, &sig_all_blocked
, &orig_mask
);
150 ERR("pthread_sigmask: %s", strerror(ret
));
152 if (!URCU_TLS(ust_mutex_nest
)++)
153 pthread_mutex_lock(&ust_mutex
);
154 ret
= pthread_sigmask(SIG_SETMASK
, &orig_mask
, NULL
);
156 ERR("pthread_sigmask: %s", strerror(ret
));
163 void ust_unlock(void)
165 sigset_t sig_all_blocked
, orig_mask
;
168 sigfillset(&sig_all_blocked
);
169 ret
= pthread_sigmask(SIG_SETMASK
, &sig_all_blocked
, &orig_mask
);
171 ERR("pthread_sigmask: %s", strerror(ret
));
173 if (!--URCU_TLS(ust_mutex_nest
))
174 pthread_mutex_unlock(&ust_mutex
);
175 ret
= pthread_sigmask(SIG_SETMASK
, &orig_mask
, NULL
);
177 ERR("pthread_sigmask: %s", strerror(ret
));
182 * Wait for either of these before continuing to the main
184 * - the register_done message from sessiond daemon
185 * (will let the sessiond daemon enable sessions before main
187 * - sessiond daemon is not reachable.
188 * - timeout (ensuring applications are resilient to session
191 static sem_t constructor_wait
;
193 * Doing this for both the global and local sessiond.
195 static int sem_count
= { 2 };
198 * Counting nesting within lttng-ust. Used to ensure that calling fork()
199 * from liblttng-ust does not execute the pre/post fork handlers.
201 static DEFINE_URCU_TLS(int, lttng_ust_nest_count
);
204 * Info about socket and associated listener thread.
208 pthread_t ust_listener
; /* listener thread */
210 int constructor_sem_posted
;
215 char sock_path
[PATH_MAX
];
219 char wait_shm_path
[PATH_MAX
];
221 /* Keep track of lazy state dump not performed yet. */
222 int statedump_pending
;
225 /* Socket from app (connect) to session daemon (listen) for communication */
226 struct sock_info global_apps
= {
234 .sock_path
= LTTNG_DEFAULT_RUNDIR
"/" LTTNG_UST_SOCK_FILENAME
,
238 .wait_shm_path
= "/" LTTNG_UST_WAIT_FILENAME
,
240 .statedump_pending
= 0,
243 /* TODO: allow global_apps_sock_path override */
245 struct sock_info local_apps
= {
249 .allowed
= 0, /* Check setuid bit first */
255 .statedump_pending
= 0,
258 static int wait_poll_fallback
;
260 static const char *cmd_name_mapping
[] = {
261 [ LTTNG_UST_RELEASE
] = "Release",
262 [ LTTNG_UST_SESSION
] = "Create Session",
263 [ LTTNG_UST_TRACER_VERSION
] = "Get Tracer Version",
265 [ LTTNG_UST_TRACEPOINT_LIST
] = "Create Tracepoint List",
266 [ LTTNG_UST_WAIT_QUIESCENT
] = "Wait for Quiescent State",
267 [ LTTNG_UST_REGISTER_DONE
] = "Registration Done",
268 [ LTTNG_UST_TRACEPOINT_FIELD_LIST
] = "Create Tracepoint Field List",
270 /* Session FD commands */
271 [ LTTNG_UST_CHANNEL
] = "Create Channel",
272 [ LTTNG_UST_SESSION_START
] = "Start Session",
273 [ LTTNG_UST_SESSION_STOP
] = "Stop Session",
275 /* Channel FD commands */
276 [ LTTNG_UST_STREAM
] = "Create Stream",
277 [ LTTNG_UST_EVENT
] = "Create Event",
279 /* Event and Channel FD commands */
280 [ LTTNG_UST_CONTEXT
] = "Create Context",
281 [ LTTNG_UST_FLUSH_BUFFER
] = "Flush Buffer",
283 /* Event, Channel and Session commands */
284 [ LTTNG_UST_ENABLE
] = "Enable",
285 [ LTTNG_UST_DISABLE
] = "Disable",
287 /* Tracepoint list commands */
288 [ LTTNG_UST_TRACEPOINT_LIST_GET
] = "List Next Tracepoint",
289 [ LTTNG_UST_TRACEPOINT_FIELD_LIST_GET
] = "List Next Tracepoint Field",
291 /* Event FD commands */
292 [ LTTNG_UST_FILTER
] = "Create Filter",
293 [ LTTNG_UST_EXCLUSION
] = "Add exclusions to event",
296 static const char *str_timeout
;
297 static int got_timeout_env
;
299 extern void lttng_ring_buffer_client_overwrite_init(void);
300 extern void lttng_ring_buffer_client_overwrite_rt_init(void);
301 extern void lttng_ring_buffer_client_discard_init(void);
302 extern void lttng_ring_buffer_client_discard_rt_init(void);
303 extern void lttng_ring_buffer_metadata_client_init(void);
304 extern void lttng_ring_buffer_client_overwrite_exit(void);
305 extern void lttng_ring_buffer_client_overwrite_rt_exit(void);
306 extern void lttng_ring_buffer_client_discard_exit(void);
307 extern void lttng_ring_buffer_client_discard_rt_exit(void);
308 extern void lttng_ring_buffer_metadata_client_exit(void);
311 * Returns the HOME directory path. Caller MUST NOT free(3) the returned
315 const char *get_lttng_home_dir(void)
319 val
= (const char *) getenv("LTTNG_HOME");
323 return (const char *) getenv("HOME");
327 * Force a read (imply TLS fixup for dlopen) of TLS variables.
330 void lttng_fixup_nest_count_tls(void)
332 asm volatile ("" : : "m" (URCU_TLS(lttng_ust_nest_count
)));
336 void lttng_fixup_ust_mutex_nest_tls(void)
338 asm volatile ("" : : "m" (URCU_TLS(ust_mutex_nest
)));
345 void lttng_fixup_urcu_bp_tls(void)
351 int lttng_get_notify_socket(void *owner
)
353 struct sock_info
*info
= owner
;
355 return info
->notify_socket
;
359 void print_cmd(int cmd
, int handle
)
361 const char *cmd_name
= "Unknown";
363 if (cmd
>= 0 && cmd
< LTTNG_ARRAY_SIZE(cmd_name_mapping
)
364 && cmd_name_mapping
[cmd
]) {
365 cmd_name
= cmd_name_mapping
[cmd
];
367 DBG("Message Received \"%s\" (%d), Handle \"%s\" (%d)",
369 lttng_ust_obj_get_name(handle
), handle
);
373 int setup_local_apps(void)
375 const char *home_dir
;
380 * Disallow per-user tracing for setuid binaries.
382 if (uid
!= geteuid()) {
383 assert(local_apps
.allowed
== 0);
386 home_dir
= get_lttng_home_dir();
388 WARN("HOME environment variable not set. Disabling LTTng-UST per-user tracing.");
389 assert(local_apps
.allowed
== 0);
392 local_apps
.allowed
= 1;
393 snprintf(local_apps
.sock_path
, PATH_MAX
, "%s/%s/%s",
395 LTTNG_DEFAULT_HOME_RUNDIR
,
396 LTTNG_UST_SOCK_FILENAME
);
397 snprintf(local_apps
.wait_shm_path
, PATH_MAX
, "/%s-%u",
398 LTTNG_UST_WAIT_FILENAME
,
404 * Get notify_sock timeout, in ms.
405 * -1: don't wait. 0: wait forever. >0: timeout, in ms.
408 long get_timeout(void)
410 long constructor_delay_ms
= LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS
;
412 if (!got_timeout_env
) {
413 str_timeout
= getenv("LTTNG_UST_REGISTER_TIMEOUT");
417 constructor_delay_ms
= strtol(str_timeout
, NULL
, 10);
418 return constructor_delay_ms
;
422 long get_notify_sock_timeout(void)
424 return get_timeout();
428 * Return values: -1: don't wait. 0: wait forever. 1: timeout wait.
431 int get_constructor_timeout(struct timespec
*constructor_timeout
)
433 long constructor_delay_ms
;
436 constructor_delay_ms
= get_timeout();
438 switch (constructor_delay_ms
) {
439 case -1:/* fall-through */
441 return constructor_delay_ms
;
447 * If we are unable to find the current time, don't wait.
449 ret
= clock_gettime(CLOCK_REALTIME
, constructor_timeout
);
453 constructor_timeout
->tv_sec
+= constructor_delay_ms
/ 1000UL;
454 constructor_timeout
->tv_nsec
+=
455 (constructor_delay_ms
% 1000UL) * 1000000UL;
456 if (constructor_timeout
->tv_nsec
>= 1000000000UL) {
457 constructor_timeout
->tv_sec
++;
458 constructor_timeout
->tv_nsec
-= 1000000000UL;
464 int register_to_sessiond(int socket
, enum ustctl_socket_type type
)
466 return ustcomm_send_reg_msg(socket
,
469 lttng_alignof(uint8_t) * CHAR_BIT
,
470 lttng_alignof(uint16_t) * CHAR_BIT
,
471 lttng_alignof(uint32_t) * CHAR_BIT
,
472 lttng_alignof(uint64_t) * CHAR_BIT
,
473 lttng_alignof(unsigned long) * CHAR_BIT
);
477 int send_reply(int sock
, struct ustcomm_ust_reply
*lur
)
481 len
= ustcomm_send_unix_sock(sock
, lur
, sizeof(*lur
));
484 DBG("message successfully sent");
487 if (len
== -ECONNRESET
) {
488 DBG("remote end closed connection");
493 DBG("incorrect message size: %zd", len
);
499 int handle_register_done(struct sock_info
*sock_info
)
503 if (sock_info
->constructor_sem_posted
)
505 sock_info
->constructor_sem_posted
= 1;
506 if (uatomic_read(&sem_count
) <= 0) {
509 ret
= uatomic_add_return(&sem_count
, -1);
511 ret
= sem_post(&constructor_wait
);
518 * Only execute pending statedump after the constructor semaphore has
519 * been posted by each listener thread. This means statedump will only
520 * be performed after the "registration done" command is received from
521 * each session daemon the application is connected to.
523 * This ensures we don't run into deadlock issues with the dynamic
524 * loader mutex, which is held while the constructor is called and
525 * waiting on the constructor semaphore. All operations requiring this
526 * dynamic loader lock need to be postponed using this mechanism.
529 void handle_pending_statedump(struct sock_info
*sock_info
)
531 int ctor_passed
= sock_info
->constructor_sem_posted
;
533 if (ctor_passed
&& sock_info
->statedump_pending
) {
534 sock_info
->statedump_pending
= 0;
535 pthread_mutex_lock(&ust_fork_mutex
);
536 lttng_handle_pending_statedump(sock_info
);
537 pthread_mutex_unlock(&ust_fork_mutex
);
542 int handle_message(struct sock_info
*sock_info
,
543 int sock
, struct ustcomm_ust_msg
*lum
)
546 const struct lttng_ust_objd_ops
*ops
;
547 struct ustcomm_ust_reply lur
;
551 memset(&lur
, 0, sizeof(lur
));
554 ret
= -LTTNG_UST_ERR_EXITING
;
558 ops
= objd_ops(lum
->handle
);
565 case LTTNG_UST_REGISTER_DONE
:
566 if (lum
->handle
== LTTNG_UST_ROOT_HANDLE
)
567 ret
= handle_register_done(sock_info
);
571 case LTTNG_UST_RELEASE
:
572 if (lum
->handle
== LTTNG_UST_ROOT_HANDLE
)
575 ret
= lttng_ust_objd_unref(lum
->handle
, 1);
577 case LTTNG_UST_FILTER
:
579 /* Receive filter data */
580 struct lttng_ust_filter_bytecode_node
*bytecode
;
582 if (lum
->u
.filter
.data_size
> FILTER_BYTECODE_MAX_LEN
) {
583 ERR("Filter data size is too large: %u bytes",
584 lum
->u
.filter
.data_size
);
589 if (lum
->u
.filter
.reloc_offset
> lum
->u
.filter
.data_size
) {
590 ERR("Filter reloc offset %u is not within data",
591 lum
->u
.filter
.reloc_offset
);
596 bytecode
= zmalloc(sizeof(*bytecode
) + lum
->u
.filter
.data_size
);
601 len
= ustcomm_recv_unix_sock(sock
, bytecode
->bc
.data
,
602 lum
->u
.filter
.data_size
);
604 case 0: /* orderly shutdown */
609 if (len
== lum
->u
.filter
.data_size
) {
610 DBG("filter data received");
612 } else if (len
< 0) {
613 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len
);
614 if (len
== -ECONNRESET
) {
615 ERR("%s remote end closed connection", sock_info
->name
);
624 DBG("incorrect filter data message size: %zd", len
);
630 bytecode
->bc
.len
= lum
->u
.filter
.data_size
;
631 bytecode
->bc
.reloc_offset
= lum
->u
.filter
.reloc_offset
;
632 bytecode
->bc
.seqnum
= lum
->u
.filter
.seqnum
;
634 ret
= ops
->cmd(lum
->handle
, lum
->cmd
,
635 (unsigned long) bytecode
,
640 /* don't free bytecode if everything went fine. */
647 case LTTNG_UST_EXCLUSION
:
649 /* Receive exclusion names */
650 struct lttng_ust_excluder_node
*node
;
653 count
= lum
->u
.exclusion
.count
;
655 /* There are no names to read */
659 node
= zmalloc(sizeof(*node
) +
660 count
* LTTNG_UST_SYM_NAME_LEN
);
665 node
->excluder
.count
= count
;
666 len
= ustcomm_recv_unix_sock(sock
, node
->excluder
.names
,
667 count
* LTTNG_UST_SYM_NAME_LEN
);
669 case 0: /* orderly shutdown */
674 if (len
== count
* LTTNG_UST_SYM_NAME_LEN
) {
675 DBG("Exclusion data received");
677 } else if (len
< 0) {
678 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len
);
679 if (len
== -ECONNRESET
) {
680 ERR("%s remote end closed connection", sock_info
->name
);
689 DBG("Incorrect exclusion data message size: %zd", len
);
696 ret
= ops
->cmd(lum
->handle
, lum
->cmd
,
697 (unsigned long) node
,
702 /* Don't free exclusion data if everything went fine. */
709 case LTTNG_UST_CHANNEL
:
714 len
= ustcomm_recv_channel_from_sessiond(sock
,
715 &chan_data
, lum
->u
.channel
.len
,
718 case 0: /* orderly shutdown */
722 if (len
== lum
->u
.channel
.len
) {
723 DBG("channel data received");
725 } else if (len
< 0) {
726 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len
);
727 if (len
== -ECONNRESET
) {
728 ERR("%s remote end closed connection", sock_info
->name
);
735 DBG("incorrect channel data message size: %zd", len
);
740 args
.channel
.chan_data
= chan_data
;
741 args
.channel
.wakeup_fd
= wakeup_fd
;
743 ret
= ops
->cmd(lum
->handle
, lum
->cmd
,
744 (unsigned long) &lum
->u
,
750 case LTTNG_UST_STREAM
:
752 /* Receive shm_fd, wakeup_fd */
753 ret
= ustcomm_recv_stream_from_sessiond(sock
,
756 &args
.stream
.wakeup_fd
);
761 ret
= ops
->cmd(lum
->handle
, lum
->cmd
,
762 (unsigned long) &lum
->u
,
770 ret
= ops
->cmd(lum
->handle
, lum
->cmd
,
771 (unsigned long) &lum
->u
,
779 lur
.handle
= lum
->handle
;
783 lur
.ret_code
= LTTNG_UST_OK
;
786 * Use -LTTNG_UST_ERR as wildcard for UST internal
787 * error that are not caused by the transport, except if
788 * we already have a more precise error message to
791 if (ret
> -LTTNG_UST_ERR
) {
792 /* Translate code to UST error. */
795 lur
.ret_code
= -LTTNG_UST_ERR_EXIST
;
798 lur
.ret_code
= -LTTNG_UST_ERR_INVAL
;
801 lur
.ret_code
= -LTTNG_UST_ERR_NOENT
;
804 lur
.ret_code
= -LTTNG_UST_ERR_PERM
;
807 lur
.ret_code
= -LTTNG_UST_ERR_NOSYS
;
810 lur
.ret_code
= -LTTNG_UST_ERR
;
819 case LTTNG_UST_TRACER_VERSION
:
820 lur
.u
.version
= lum
->u
.version
;
822 case LTTNG_UST_TRACEPOINT_LIST_GET
:
823 memcpy(&lur
.u
.tracepoint
, &lum
->u
.tracepoint
, sizeof(lur
.u
.tracepoint
));
827 DBG("Return value: %d", lur
.ret_val
);
828 ret
= send_reply(sock
, &lur
);
830 DBG("error sending reply");
835 * LTTNG_UST_TRACEPOINT_FIELD_LIST_GET needs to send the field
838 if (lur
.ret_code
== LTTNG_UST_OK
) {
840 case LTTNG_UST_TRACEPOINT_FIELD_LIST_GET
:
841 len
= ustcomm_send_unix_sock(sock
,
842 &args
.field_list
.entry
,
843 sizeof(args
.field_list
.entry
));
848 if (len
!= sizeof(args
.field_list
.entry
)) {
859 * Performed delayed statedump operations outside of the UST
860 * lock. We need to take the dynamic loader lock before we take
861 * the UST lock internally within handle_pending_statedump().
863 handle_pending_statedump(sock_info
);
869 void cleanup_sock_info(struct sock_info
*sock_info
, int exiting
)
873 if (sock_info
->root_handle
!= -1) {
874 ret
= lttng_ust_objd_unref(sock_info
->root_handle
, 1);
876 ERR("Error unref root handle");
878 sock_info
->root_handle
= -1;
880 sock_info
->constructor_sem_posted
= 0;
883 * wait_shm_mmap, socket and notify socket are used by listener
884 * threads outside of the ust lock, so we cannot tear them down
885 * ourselves, because we cannot join on these threads. Leave
886 * responsibility of cleaning up these resources to the OS
892 if (sock_info
->socket
!= -1) {
893 ret
= ustcomm_close_unix_sock(sock_info
->socket
);
895 ERR("Error closing ust cmd socket");
897 sock_info
->socket
= -1;
899 if (sock_info
->notify_socket
!= -1) {
900 ret
= ustcomm_close_unix_sock(sock_info
->notify_socket
);
902 ERR("Error closing ust notify socket");
904 sock_info
->notify_socket
= -1;
906 if (sock_info
->wait_shm_mmap
) {
909 page_size
= sysconf(_SC_PAGE_SIZE
);
911 ret
= munmap(sock_info
->wait_shm_mmap
, page_size
);
913 ERR("Error unmapping wait shm");
916 sock_info
->wait_shm_mmap
= NULL
;
921 * Using fork to set umask in the child process (not multi-thread safe).
922 * We deal with the shm_open vs ftruncate race (happening when the
923 * sessiond owns the shm and does not let everybody modify it, to ensure
924 * safety against shm_unlink) by simply letting the mmap fail and
925 * retrying after a few seconds.
926 * For global shm, everybody has rw access to it until the sessiond
930 int get_wait_shm(struct sock_info
*sock_info
, size_t mmap_size
)
932 int wait_shm_fd
, ret
;
936 * Try to open read-only.
938 wait_shm_fd
= shm_open(sock_info
->wait_shm_path
, O_RDONLY
, 0);
939 if (wait_shm_fd
>= 0) {
942 size_t bytes_read
= 0;
945 * Try to read the fd. If unable to do so, try opening
949 len
= read(wait_shm_fd
,
950 &((char *) &tmp_read
)[bytes_read
],
951 sizeof(tmp_read
) - bytes_read
);
955 } while ((len
< 0 && errno
== EINTR
)
956 || (len
> 0 && bytes_read
< sizeof(tmp_read
)));
957 if (bytes_read
!= sizeof(tmp_read
)) {
958 ret
= close(wait_shm_fd
);
960 ERR("close wait_shm_fd");
965 } else if (wait_shm_fd
< 0 && errno
!= ENOENT
) {
967 * Real-only open did not work, and it's not because the
968 * entry was not present. It's a failure that prohibits
971 ERR("Error opening shm %s", sock_info
->wait_shm_path
);
977 * If the open failed because the file did not exist, or because
978 * the file was not truncated yet, try creating it ourself.
980 URCU_TLS(lttng_ust_nest_count
)++;
982 URCU_TLS(lttng_ust_nest_count
)--;
987 * Parent: wait for child to return, in which case the
988 * shared memory map will have been created.
991 if (pid
< 0 || !WIFEXITED(status
) || WEXITSTATUS(status
) != 0) {
996 * Try to open read-only again after creation.
998 wait_shm_fd
= shm_open(sock_info
->wait_shm_path
, O_RDONLY
, 0);
999 if (wait_shm_fd
< 0) {
1001 * Real-only open did not work. It's a failure
1002 * that prohibits using shm.
1004 ERR("Error opening shm %s", sock_info
->wait_shm_path
);
1008 } else if (pid
== 0) {
1012 create_mode
= S_IRUSR
| S_IWUSR
| S_IRGRP
;
1013 if (sock_info
->global
)
1014 create_mode
|= S_IROTH
| S_IWGRP
| S_IWOTH
;
1016 * We're alone in a child process, so we can modify the
1017 * process-wide umask.
1019 umask(~create_mode
);
1021 * Try creating shm (or get rw access).
1022 * We don't do an exclusive open, because we allow other
1023 * processes to create+ftruncate it concurrently.
1025 wait_shm_fd
= shm_open(sock_info
->wait_shm_path
,
1026 O_RDWR
| O_CREAT
, create_mode
);
1027 if (wait_shm_fd
>= 0) {
1028 ret
= ftruncate(wait_shm_fd
, mmap_size
);
1030 PERROR("ftruncate");
1031 _exit(EXIT_FAILURE
);
1033 _exit(EXIT_SUCCESS
);
1036 * For local shm, we need to have rw access to accept
1037 * opening it: this means the local sessiond will be
1038 * able to wake us up. For global shm, we open it even
1039 * if rw access is not granted, because the root.root
1040 * sessiond will be able to override all rights and wake
1043 if (!sock_info
->global
&& errno
!= EACCES
) {
1044 ERR("Error opening shm %s", sock_info
->wait_shm_path
);
1045 _exit(EXIT_FAILURE
);
1048 * The shm exists, but we cannot open it RW. Report
1051 _exit(EXIT_SUCCESS
);
1056 if (wait_shm_fd
>= 0 && !sock_info
->global
) {
1057 struct stat statbuf
;
1060 * Ensure that our user is the owner of the shm file for
1061 * local shm. If we do not own the file, it means our
1062 * sessiond will not have access to wake us up (there is
1063 * probably a rogue process trying to fake our
1064 * sessiond). Fallback to polling method in this case.
1066 ret
= fstat(wait_shm_fd
, &statbuf
);
1071 if (statbuf
.st_uid
!= getuid())
1077 ret
= close(wait_shm_fd
);
1079 PERROR("Error closing fd");
1085 char *get_map_shm(struct sock_info
*sock_info
)
1088 int wait_shm_fd
, ret
;
1089 char *wait_shm_mmap
;
1091 page_size
= sysconf(_SC_PAGE_SIZE
);
1092 if (page_size
< 0) {
1096 wait_shm_fd
= get_wait_shm(sock_info
, page_size
);
1097 if (wait_shm_fd
< 0) {
1100 wait_shm_mmap
= mmap(NULL
, page_size
, PROT_READ
,
1101 MAP_SHARED
, wait_shm_fd
, 0);
1102 /* close shm fd immediately after taking the mmap reference */
1103 ret
= close(wait_shm_fd
);
1105 PERROR("Error closing fd");
1107 if (wait_shm_mmap
== MAP_FAILED
) {
1108 DBG("mmap error (can be caused by race with sessiond). Fallback to poll mode.");
1111 return wait_shm_mmap
;
1118 void wait_for_sessiond(struct sock_info
*sock_info
)
1125 if (wait_poll_fallback
) {
1128 if (!sock_info
->wait_shm_mmap
) {
1129 sock_info
->wait_shm_mmap
= get_map_shm(sock_info
);
1130 if (!sock_info
->wait_shm_mmap
)
1135 DBG("Waiting for %s apps sessiond", sock_info
->name
);
1136 /* Wait for futex wakeup */
1137 if (uatomic_read((int32_t *) sock_info
->wait_shm_mmap
) == 0) {
1138 ret
= futex_async((int32_t *) sock_info
->wait_shm_mmap
,
1139 FUTEX_WAIT
, 0, NULL
, NULL
, 0);
1141 if (errno
== EFAULT
) {
1142 wait_poll_fallback
= 1;
1144 "Linux kernels 2.6.33 to 3.0 (with the exception of stable versions) "
1145 "do not support FUTEX_WAKE on read-only memory mappings correctly. "
1146 "Please upgrade your kernel "
1147 "(fix is commit 9ea71503a8ed9184d2d0b8ccc4d269d05f7940ae in Linux kernel "
1148 "mainline). LTTng-UST will use polling mode fallback.");
1166 * This thread does not allocate any resource, except within
1167 * handle_message, within mutex protection. This mutex protects against
1169 * The other moment it allocates resources is at socket connection, which
1170 * is also protected by the mutex.
1173 void *ust_listener_thread(void *arg
)
1175 struct sock_info
*sock_info
= arg
;
1176 int sock
, ret
, prev_connect_failed
= 0, has_waited
= 0;
1179 /* Restart trying to connect to the session daemon */
1181 if (prev_connect_failed
) {
1182 /* Wait for sessiond availability with pipe */
1183 wait_for_sessiond(sock_info
);
1187 * Sleep for 5 seconds before retrying after a
1188 * sequence of failure / wait / failure. This
1189 * deals with a killed or broken session daemon.
1194 prev_connect_failed
= 0;
1197 if (sock_info
->socket
!= -1) {
1198 ret
= ustcomm_close_unix_sock(sock_info
->socket
);
1200 ERR("Error closing %s ust cmd socket",
1203 sock_info
->socket
= -1;
1205 if (sock_info
->notify_socket
!= -1) {
1206 ret
= ustcomm_close_unix_sock(sock_info
->notify_socket
);
1208 ERR("Error closing %s ust notify socket",
1211 sock_info
->notify_socket
= -1;
1215 * Register. We need to perform both connect and sending
1216 * registration message before doing the next connect otherwise
1217 * we may reach unix socket connect queue max limits and block
1218 * on the 2nd connect while the session daemon is awaiting the
1219 * first connect registration message.
1221 /* Connect cmd socket */
1222 ret
= ustcomm_connect_unix_sock(sock_info
->sock_path
);
1224 DBG("Info: sessiond not accepting connections to %s apps socket", sock_info
->name
);
1225 prev_connect_failed
= 1;
1232 * If we cannot find the sessiond daemon, don't delay
1233 * constructor execution.
1235 ret
= handle_register_done(sock_info
);
1240 sock_info
->socket
= ret
;
1247 * Create only one root handle per listener thread for the whole
1248 * process lifetime, so we ensure we get ID which is statically
1249 * assigned to the root handle.
1251 if (sock_info
->root_handle
== -1) {
1252 ret
= lttng_abi_create_root_handle();
1254 ERR("Error creating root handle");
1257 sock_info
->root_handle
= ret
;
1260 ret
= register_to_sessiond(sock_info
->socket
, USTCTL_SOCKET_CMD
);
1262 ERR("Error registering to %s ust cmd socket",
1264 prev_connect_failed
= 1;
1266 * If we cannot register to the sessiond daemon, don't
1267 * delay constructor execution.
1269 ret
= handle_register_done(sock_info
);
1277 /* Connect notify socket */
1278 ret
= ustcomm_connect_unix_sock(sock_info
->sock_path
);
1280 DBG("Info: sessiond not accepting connections to %s apps socket", sock_info
->name
);
1281 prev_connect_failed
= 1;
1288 * If we cannot find the sessiond daemon, don't delay
1289 * constructor execution.
1291 ret
= handle_register_done(sock_info
);
1296 sock_info
->notify_socket
= ret
;
1298 timeout
= get_notify_sock_timeout();
1301 * Give at least 10ms to sessiond to reply to
1306 ret
= ustcomm_setsockopt_rcv_timeout(sock_info
->notify_socket
,
1309 WARN("Error setting socket receive timeout");
1311 ret
= ustcomm_setsockopt_snd_timeout(sock_info
->notify_socket
,
1314 WARN("Error setting socket send timeout");
1316 } else if (timeout
< -1) {
1317 WARN("Unsupported timeout value %ld", timeout
);
1324 ret
= register_to_sessiond(sock_info
->notify_socket
,
1325 USTCTL_SOCKET_NOTIFY
);
1327 ERR("Error registering to %s ust notify socket",
1329 prev_connect_failed
= 1;
1331 * If we cannot register to the sessiond daemon, don't
1332 * delay constructor execution.
1334 ret
= handle_register_done(sock_info
);
1339 sock
= sock_info
->socket
;
1345 struct ustcomm_ust_msg lum
;
1347 len
= ustcomm_recv_unix_sock(sock
, &lum
, sizeof(lum
));
1349 case 0: /* orderly shutdown */
1350 DBG("%s lttng-sessiond has performed an orderly shutdown", sock_info
->name
);
1355 * Either sessiond has shutdown or refused us by closing the socket.
1356 * In either case, we don't want to delay construction execution,
1357 * and we need to wait before retry.
1359 prev_connect_failed
= 1;
1361 * If we cannot register to the sessiond daemon, don't
1362 * delay constructor execution.
1364 ret
= handle_register_done(sock_info
);
1369 print_cmd(lum
.cmd
, lum
.handle
);
1370 ret
= handle_message(sock_info
, sock
, &lum
);
1372 ERR("Error handling message for %s socket", sock_info
->name
);
1377 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len
);
1379 DBG("incorrect message size (%s socket): %zd", sock_info
->name
, len
);
1381 if (len
== -ECONNRESET
) {
1382 DBG("%s remote end closed connection", sock_info
->name
);
1393 /* Cleanup socket handles before trying to reconnect */
1394 lttng_ust_objd_table_owner_cleanup(sock_info
);
1396 goto restart
; /* try to reconnect */
1401 pthread_mutex_lock(&ust_exit_mutex
);
1402 sock_info
->thread_active
= 0;
1403 pthread_mutex_unlock(&ust_exit_mutex
);
1408 * Weak symbol to call when the ust malloc wrapper is not loaded.
1410 __attribute__((weak
))
1411 void lttng_ust_malloc_wrapper_init(void)
1416 * sessiond monitoring thread: monitor presence of global and per-user
1417 * sessiond by polling the application common named pipe.
1419 void __attribute__((constructor
)) lttng_ust_init(void)
1421 struct timespec constructor_timeout
;
1422 sigset_t sig_all_blocked
, orig_parent_mask
;
1423 pthread_attr_t thread_attr
;
1427 if (uatomic_xchg(&initialized
, 1) == 1)
1431 * Fixup interdependency between TLS fixup mutex (which happens
1432 * to be the dynamic linker mutex) and ust_lock, taken within
1435 lttng_fixup_urcu_bp_tls();
1436 lttng_fixup_ringbuffer_tls();
1437 lttng_fixup_vtid_tls();
1438 lttng_fixup_nest_count_tls();
1439 lttng_fixup_procname_tls();
1440 lttng_fixup_ust_mutex_nest_tls();
1443 * We want precise control over the order in which we construct
1444 * our sub-libraries vs starting to receive commands from
1445 * sessiond (otherwise leading to errors when trying to create
1446 * sessiond before the init functions are completed).
1450 lttng_ust_clock_init();
1451 lttng_ust_getcpu_init();
1452 lttng_ust_baddr_statedump_init();
1453 lttng_ring_buffer_metadata_client_init();
1454 lttng_ring_buffer_client_overwrite_init();
1455 lttng_ring_buffer_client_overwrite_rt_init();
1456 lttng_ring_buffer_client_discard_init();
1457 lttng_ring_buffer_client_discard_rt_init();
1458 lttng_perf_counter_init();
1459 lttng_context_init();
1461 * Invoke ust malloc wrapper init before starting other threads.
1463 lttng_ust_malloc_wrapper_init();
1465 timeout_mode
= get_constructor_timeout(&constructor_timeout
);
1467 ret
= sem_init(&constructor_wait
, 0, 0);
1470 ret
= setup_local_apps();
1472 DBG("local apps setup returned %d", ret
);
1475 /* A new thread created by pthread_create inherits the signal mask
1476 * from the parent. To avoid any signal being received by the
1477 * listener thread, we block all signals temporarily in the parent,
1478 * while we create the listener thread.
1480 sigfillset(&sig_all_blocked
);
1481 ret
= pthread_sigmask(SIG_SETMASK
, &sig_all_blocked
, &orig_parent_mask
);
1483 ERR("pthread_sigmask: %s", strerror(ret
));
1486 ret
= pthread_attr_init(&thread_attr
);
1488 ERR("pthread_attr_init: %s", strerror(ret
));
1490 ret
= pthread_attr_setdetachstate(&thread_attr
, PTHREAD_CREATE_DETACHED
);
1492 ERR("pthread_attr_setdetachstate: %s", strerror(ret
));
1495 pthread_mutex_lock(&ust_exit_mutex
);
1496 ret
= pthread_create(&global_apps
.ust_listener
, &thread_attr
,
1497 ust_listener_thread
, &global_apps
);
1499 ERR("pthread_create global: %s", strerror(ret
));
1501 global_apps
.thread_active
= 1;
1502 pthread_mutex_unlock(&ust_exit_mutex
);
1504 if (local_apps
.allowed
) {
1505 pthread_mutex_lock(&ust_exit_mutex
);
1506 ret
= pthread_create(&local_apps
.ust_listener
, &thread_attr
,
1507 ust_listener_thread
, &local_apps
);
1509 ERR("pthread_create local: %s", strerror(ret
));
1511 local_apps
.thread_active
= 1;
1512 pthread_mutex_unlock(&ust_exit_mutex
);
1514 handle_register_done(&local_apps
);
1516 ret
= pthread_attr_destroy(&thread_attr
);
1518 ERR("pthread_attr_destroy: %s", strerror(ret
));
1521 /* Restore original signal mask in parent */
1522 ret
= pthread_sigmask(SIG_SETMASK
, &orig_parent_mask
, NULL
);
1524 ERR("pthread_sigmask: %s", strerror(ret
));
1527 switch (timeout_mode
) {
1528 case 1: /* timeout wait */
1530 ret
= sem_timedwait(&constructor_wait
,
1531 &constructor_timeout
);
1532 } while (ret
< 0 && errno
== EINTR
);
1533 if (ret
< 0 && errno
== ETIMEDOUT
) {
1534 ERR("Timed out waiting for lttng-sessiond");
1539 case -1:/* wait forever */
1541 ret
= sem_wait(&constructor_wait
);
1542 } while (ret
< 0 && errno
== EINTR
);
1545 case 0: /* no timeout */
1551 void lttng_ust_cleanup(int exiting
)
1553 cleanup_sock_info(&global_apps
, exiting
);
1554 if (local_apps
.allowed
) {
1555 cleanup_sock_info(&local_apps
, exiting
);
1558 * The teardown in this function all affect data structures
1559 * accessed under the UST lock by the listener thread. This
1560 * lock, along with the lttng_ust_comm_should_quit flag, ensure
1561 * that none of these threads are accessing this data at this
1564 lttng_ust_abi_exit();
1565 lttng_ust_events_exit();
1566 lttng_context_exit();
1567 lttng_perf_counter_exit();
1568 lttng_ring_buffer_client_discard_rt_exit();
1569 lttng_ring_buffer_client_discard_exit();
1570 lttng_ring_buffer_client_overwrite_rt_exit();
1571 lttng_ring_buffer_client_overwrite_exit();
1572 lttng_ring_buffer_metadata_client_exit();
1573 lttng_ust_baddr_statedump_destroy();
1576 /* Reinitialize values for fork */
1578 lttng_ust_comm_should_quit
= 0;
1583 void __attribute__((destructor
)) lttng_ust_exit(void)
1588 * Using pthread_cancel here because:
1589 * A) we don't want to hang application teardown.
1590 * B) the thread is not allocating any resource.
1594 * Require the communication thread to quit. Synchronize with
1595 * mutexes to ensure it is not in a mutex critical section when
1596 * pthread_cancel is later called.
1599 lttng_ust_comm_should_quit
= 1;
1602 pthread_mutex_lock(&ust_exit_mutex
);
1603 /* cancel threads */
1604 if (global_apps
.thread_active
) {
1605 ret
= pthread_cancel(global_apps
.ust_listener
);
1607 ERR("Error cancelling global ust listener thread: %s",
1610 global_apps
.thread_active
= 0;
1613 if (local_apps
.thread_active
) {
1614 ret
= pthread_cancel(local_apps
.ust_listener
);
1616 ERR("Error cancelling local ust listener thread: %s",
1619 local_apps
.thread_active
= 0;
1622 pthread_mutex_unlock(&ust_exit_mutex
);
1625 * Do NOT join threads: use of sys_futex makes it impossible to
1626 * join the threads without using async-cancel, but async-cancel
1627 * is delivered by a signal, which could hit the target thread
1628 * anywhere in its code path, including while the ust_lock() is
1629 * held, causing a deadlock for the other thread. Let the OS
1630 * cleanup the threads if there are stalled in a syscall.
1632 lttng_ust_cleanup(1);
1636 * We exclude the worker threads across fork and clone (except
1637 * CLONE_VM), because these system calls only keep the forking thread
1638 * running in the child. Therefore, we don't want to call fork or clone
1639 * in the middle of an tracepoint or ust tracing state modification.
1640 * Holding this mutex protects these structures across fork and clone.
1642 void ust_before_fork(sigset_t
*save_sigset
)
1645 * Disable signals. This is to avoid that the child intervenes
1646 * before it is properly setup for tracing. It is safer to
1647 * disable all signals, because then we know we are not breaking
1648 * anything by restoring the original mask.
1653 if (URCU_TLS(lttng_ust_nest_count
))
1655 /* Disable signals */
1656 sigfillset(&all_sigs
);
1657 ret
= sigprocmask(SIG_BLOCK
, &all_sigs
, save_sigset
);
1659 PERROR("sigprocmask");
1662 pthread_mutex_lock(&ust_fork_mutex
);
1665 rcu_bp_before_fork();
1668 static void ust_after_fork_common(sigset_t
*restore_sigset
)
1672 DBG("process %d", getpid());
1675 pthread_mutex_unlock(&ust_fork_mutex
);
1677 /* Restore signals */
1678 ret
= sigprocmask(SIG_SETMASK
, restore_sigset
, NULL
);
1680 PERROR("sigprocmask");
1684 void ust_after_fork_parent(sigset_t
*restore_sigset
)
1686 if (URCU_TLS(lttng_ust_nest_count
))
1688 DBG("process %d", getpid());
1689 rcu_bp_after_fork_parent();
1690 /* Release mutexes and reenable signals */
1691 ust_after_fork_common(restore_sigset
);
1695 * After fork, in the child, we need to cleanup all the leftover state,
1696 * except the worker thread which already magically disappeared thanks
1697 * to the weird Linux fork semantics. After tyding up, we call
1698 * lttng_ust_init() again to start over as a new PID.
1700 * This is meant for forks() that have tracing in the child between the
1701 * fork and following exec call (if there is any).
1703 void ust_after_fork_child(sigset_t
*restore_sigset
)
1705 if (URCU_TLS(lttng_ust_nest_count
))
1707 DBG("process %d", getpid());
1708 /* Release urcu mutexes */
1709 rcu_bp_after_fork_child();
1710 lttng_ust_cleanup(0);
1711 lttng_context_vtid_reset();
1712 /* Release mutexes and reenable signals */
1713 ust_after_fork_common(restore_sigset
);
1717 void lttng_ust_sockinfo_session_enabled(void *owner
)
1719 struct sock_info
*sock_info
= owner
;
1720 sock_info
->statedump_pending
= 1;