Commit | Line | Data |
---|---|---|
2691221a MD |
1 | /* |
2 | * lttng-ust-comm.c | |
3 | * | |
4 | * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca> | |
5 | * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
6 | * | |
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. | |
11 | * | |
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. | |
16 | * | |
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 | |
20 | */ | |
21 | ||
80e2814b | 22 | #define _LGPL_SOURCE |
2691221a MD |
23 | #include <sys/types.h> |
24 | #include <sys/socket.h> | |
4c1ee94e | 25 | #include <sys/prctl.h> |
7fc90dca MD |
26 | #include <sys/mman.h> |
27 | #include <sys/stat.h> | |
58d4b2a2 MD |
28 | #include <sys/types.h> |
29 | #include <sys/wait.h> | |
7fc90dca | 30 | #include <fcntl.h> |
2691221a MD |
31 | #include <unistd.h> |
32 | #include <errno.h> | |
d9e99d10 | 33 | #include <pthread.h> |
11ff9c7d MD |
34 | #include <semaphore.h> |
35 | #include <time.h> | |
1ea11eab | 36 | #include <assert.h> |
e822f505 | 37 | #include <signal.h> |
95259bd0 | 38 | #include <urcu/uatomic.h> |
80e2814b | 39 | #include <urcu/futex.h> |
c117fb1b | 40 | #include <urcu/compiler.h> |
1ea11eab | 41 | |
4318ae1b | 42 | #include <lttng/ust-events.h> |
4318ae1b | 43 | #include <lttng/ust-abi.h> |
4318ae1b | 44 | #include <lttng/ust.h> |
44c72f10 MD |
45 | #include <ust-comm.h> |
46 | #include <usterr-signal-safe.h> | |
47 | #include "tracepoint-internal.h" | |
b751f722 | 48 | #include "ltt-tracer-core.h" |
f645cfa7 | 49 | #include "../libringbuffer/tlsfixup.h" |
edaa1431 MD |
50 | |
51 | /* | |
52 | * Has lttng ust comm constructor been called ? | |
53 | */ | |
54 | static int initialized; | |
55 | ||
1ea11eab | 56 | /* |
17dfb34b MD |
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. | |
1ea11eab | 60 | */ |
1ea11eab MD |
61 | |
62 | /* Should the ust comm thread quit ? */ | |
63 | static int lttng_ust_comm_should_quit; | |
64 | ||
11ff9c7d MD |
65 | /* |
66 | * Wait for either of these before continuing to the main | |
67 | * program: | |
68 | * - the register_done message from sessiond daemon | |
69 | * (will let the sessiond daemon enable sessions before main | |
70 | * starts.) | |
71 | * - sessiond daemon is not reachable. | |
72 | * - timeout (ensuring applications are resilient to session | |
73 | * daemon problems). | |
74 | */ | |
75 | static sem_t constructor_wait; | |
950aab0c MD |
76 | /* |
77 | * Doing this for both the global and local sessiond. | |
78 | */ | |
95259bd0 | 79 | static int sem_count = { 2 }; |
11ff9c7d | 80 | |
3b8b68e7 MD |
81 | /* |
82 | * Counting nesting within lttng-ust. Used to ensure that calling fork() | |
83 | * from liblttng-ust does not execute the pre/post fork handlers. | |
84 | */ | |
85 | static int __thread lttng_ust_nest_count; | |
86 | ||
1ea11eab MD |
87 | /* |
88 | * Info about socket and associated listener thread. | |
89 | */ | |
90 | struct sock_info { | |
11ff9c7d | 91 | const char *name; |
1ea11eab | 92 | pthread_t ust_listener; /* listener thread */ |
46050b1a | 93 | int root_handle; |
8d20bf54 MD |
94 | int constructor_sem_posted; |
95 | int allowed; | |
44e073f5 | 96 | int global; |
7fc90dca MD |
97 | |
98 | char sock_path[PATH_MAX]; | |
99 | int socket; | |
100 | ||
101 | char wait_shm_path[PATH_MAX]; | |
102 | char *wait_shm_mmap; | |
1ea11eab | 103 | }; |
2691221a MD |
104 | |
105 | /* Socket from app (connect) to session daemon (listen) for communication */ | |
1ea11eab | 106 | struct sock_info global_apps = { |
11ff9c7d | 107 | .name = "global", |
44e073f5 | 108 | .global = 1, |
7fc90dca | 109 | |
46050b1a | 110 | .root_handle = -1, |
8d20bf54 | 111 | .allowed = 1, |
7fc90dca MD |
112 | |
113 | .sock_path = DEFAULT_GLOBAL_APPS_UNIX_SOCK, | |
114 | .socket = -1, | |
115 | ||
116 | .wait_shm_path = DEFAULT_GLOBAL_APPS_WAIT_SHM_PATH, | |
1ea11eab | 117 | }; |
2691221a MD |
118 | |
119 | /* TODO: allow global_apps_sock_path override */ | |
120 | ||
1ea11eab | 121 | struct sock_info local_apps = { |
11ff9c7d | 122 | .name = "local", |
44e073f5 | 123 | .global = 0, |
46050b1a | 124 | .root_handle = -1, |
8d20bf54 | 125 | .allowed = 0, /* Check setuid bit first */ |
7fc90dca MD |
126 | |
127 | .socket = -1, | |
1ea11eab | 128 | }; |
2691221a | 129 | |
37ed587a MD |
130 | static int wait_poll_fallback; |
131 | ||
edaa1431 MD |
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); | |
138 | ||
e38c8fc1 MD |
139 | /* |
140 | * Force a read (imply TLS fixup for dlopen) of TLS variables. | |
141 | */ | |
142 | static | |
143 | void lttng_fixup_nest_count_tls(void) | |
144 | { | |
145 | asm volatile ("" : : "m" (lttng_ust_nest_count)); | |
146 | } | |
147 | ||
2691221a | 148 | static |
8d20bf54 | 149 | int setup_local_apps(void) |
2691221a MD |
150 | { |
151 | const char *home_dir; | |
7fc90dca | 152 | uid_t uid; |
2691221a | 153 | |
7fc90dca | 154 | uid = getuid(); |
8d20bf54 MD |
155 | /* |
156 | * Disallow per-user tracing for setuid binaries. | |
157 | */ | |
7fc90dca | 158 | if (uid != geteuid()) { |
e699eda9 | 159 | assert(local_apps.allowed == 0); |
d0a1ae63 | 160 | return 0; |
8d20bf54 | 161 | } |
2691221a | 162 | home_dir = (const char *) getenv("HOME"); |
e699eda9 MD |
163 | if (!home_dir) { |
164 | WARN("HOME environment variable not set. Disabling LTTng-UST per-user tracing."); | |
165 | assert(local_apps.allowed == 0); | |
2691221a | 166 | return -ENOENT; |
e699eda9 MD |
167 | } |
168 | local_apps.allowed = 1; | |
1ea11eab | 169 | snprintf(local_apps.sock_path, PATH_MAX, |
2691221a | 170 | DEFAULT_HOME_APPS_UNIX_SOCK, home_dir); |
7fc90dca MD |
171 | snprintf(local_apps.wait_shm_path, PATH_MAX, |
172 | DEFAULT_HOME_APPS_WAIT_SHM_PATH, uid); | |
2691221a MD |
173 | return 0; |
174 | } | |
175 | ||
176 | static | |
177 | int register_app_to_sessiond(int socket) | |
178 | { | |
179 | ssize_t ret; | |
4c1ee94e | 180 | int prctl_ret; |
2691221a | 181 | struct { |
e44418f3 MD |
182 | uint32_t major; |
183 | uint32_t minor; | |
2691221a | 184 | pid_t pid; |
5c33bde8 | 185 | pid_t ppid; |
2691221a | 186 | uid_t uid; |
83610856 | 187 | gid_t gid; |
c117fb1b | 188 | uint32_t bits_per_long; |
2629549e | 189 | char name[16]; /* process name */ |
2691221a MD |
190 | } reg_msg; |
191 | ||
e44418f3 MD |
192 | reg_msg.major = LTTNG_UST_COMM_VERSION_MAJOR; |
193 | reg_msg.minor = LTTNG_UST_COMM_VERSION_MINOR; | |
2691221a | 194 | reg_msg.pid = getpid(); |
5c33bde8 | 195 | reg_msg.ppid = getppid(); |
2691221a | 196 | reg_msg.uid = getuid(); |
83610856 | 197 | reg_msg.gid = getgid(); |
c117fb1b | 198 | reg_msg.bits_per_long = CAA_BITS_PER_LONG; |
4c1ee94e MD |
199 | prctl_ret = prctl(PR_GET_NAME, (unsigned long) reg_msg.name, 0, 0, 0); |
200 | if (prctl_ret) { | |
201 | ERR("Error executing prctl"); | |
202 | return -errno; | |
203 | } | |
2691221a | 204 | |
57773204 | 205 | ret = ustcomm_send_unix_sock(socket, ®_msg, sizeof(reg_msg)); |
2691221a MD |
206 | if (ret >= 0 && ret != sizeof(reg_msg)) |
207 | return -EIO; | |
208 | return ret; | |
209 | } | |
210 | ||
d9e99d10 | 211 | static |
57773204 | 212 | int send_reply(int sock, struct ustcomm_ust_reply *lur) |
d9e99d10 | 213 | { |
9eb62b9c | 214 | ssize_t len; |
d3a492d1 | 215 | |
57773204 | 216 | len = ustcomm_send_unix_sock(sock, lur, sizeof(*lur)); |
d3a492d1 | 217 | switch (len) { |
a4be8962 | 218 | case sizeof(*lur): |
d3a492d1 MD |
219 | DBG("message successfully sent"); |
220 | return 0; | |
221 | case -1: | |
222 | if (errno == ECONNRESET) { | |
223 | printf("remote end closed connection\n"); | |
224 | return 0; | |
225 | } | |
226 | return -1; | |
227 | default: | |
228 | printf("incorrect message size: %zd\n", len); | |
229 | return -1; | |
230 | } | |
231 | } | |
232 | ||
233 | static | |
edaa1431 | 234 | int handle_register_done(struct sock_info *sock_info) |
11ff9c7d MD |
235 | { |
236 | int ret; | |
237 | ||
edaa1431 MD |
238 | if (sock_info->constructor_sem_posted) |
239 | return 0; | |
240 | sock_info->constructor_sem_posted = 1; | |
56cd7e2f MD |
241 | if (uatomic_read(&sem_count) <= 0) { |
242 | return 0; | |
243 | } | |
95259bd0 MD |
244 | ret = uatomic_add_return(&sem_count, -1); |
245 | if (ret == 0) { | |
246 | ret = sem_post(&constructor_wait); | |
247 | assert(!ret); | |
248 | } | |
11ff9c7d MD |
249 | return 0; |
250 | } | |
251 | ||
252 | static | |
253 | int handle_message(struct sock_info *sock_info, | |
57773204 | 254 | int sock, struct ustcomm_ust_msg *lum) |
d3a492d1 | 255 | { |
1ea11eab | 256 | int ret = 0; |
b61ce3b2 | 257 | const struct lttng_ust_objd_ops *ops; |
57773204 | 258 | struct ustcomm_ust_reply lur; |
193183fb | 259 | int shm_fd, wait_fd; |
ef9ff354 | 260 | union ust_args args; |
1ea11eab | 261 | |
17dfb34b | 262 | ust_lock(); |
1ea11eab | 263 | |
46050b1a MD |
264 | memset(&lur, 0, sizeof(lur)); |
265 | ||
1ea11eab | 266 | if (lttng_ust_comm_should_quit) { |
46050b1a | 267 | ret = -EPERM; |
1ea11eab MD |
268 | goto end; |
269 | } | |
9eb62b9c | 270 | |
46050b1a MD |
271 | ops = objd_ops(lum->handle); |
272 | if (!ops) { | |
273 | ret = -ENOENT; | |
274 | goto end; | |
1ea11eab | 275 | } |
46050b1a MD |
276 | |
277 | switch (lum->cmd) { | |
11ff9c7d MD |
278 | case LTTNG_UST_REGISTER_DONE: |
279 | if (lum->handle == LTTNG_UST_ROOT_HANDLE) | |
edaa1431 | 280 | ret = handle_register_done(sock_info); |
11ff9c7d MD |
281 | else |
282 | ret = -EINVAL; | |
283 | break; | |
46050b1a MD |
284 | case LTTNG_UST_RELEASE: |
285 | if (lum->handle == LTTNG_UST_ROOT_HANDLE) | |
286 | ret = -EPERM; | |
287 | else | |
d4419b81 | 288 | ret = lttng_ust_objd_unref(lum->handle); |
d9e99d10 MD |
289 | break; |
290 | default: | |
46050b1a MD |
291 | if (ops->cmd) |
292 | ret = ops->cmd(lum->handle, lum->cmd, | |
ef9ff354 MD |
293 | (unsigned long) &lum->u, |
294 | &args); | |
46050b1a MD |
295 | else |
296 | ret = -ENOSYS; | |
297 | break; | |
d9e99d10 | 298 | } |
46050b1a | 299 | |
1ea11eab | 300 | end: |
46050b1a MD |
301 | lur.handle = lum->handle; |
302 | lur.cmd = lum->cmd; | |
303 | lur.ret_val = ret; | |
304 | if (ret >= 0) { | |
57773204 | 305 | lur.ret_code = USTCOMM_OK; |
46050b1a | 306 | } else { |
57773204 | 307 | //lur.ret_code = USTCOMM_SESSION_FAIL; |
193183fb | 308 | lur.ret_code = ret; |
46050b1a | 309 | } |
e6ea14c5 MD |
310 | if (ret >= 0) { |
311 | switch (lum->cmd) { | |
312 | case LTTNG_UST_STREAM: | |
313 | /* | |
314 | * Special-case reply to send stream info. | |
315 | * Use lum.u output. | |
316 | */ | |
317 | lur.u.stream.memory_map_size = *args.stream.memory_map_size; | |
318 | shm_fd = *args.stream.shm_fd; | |
319 | wait_fd = *args.stream.wait_fd; | |
320 | break; | |
321 | case LTTNG_UST_METADATA: | |
322 | case LTTNG_UST_CHANNEL: | |
323 | lur.u.channel.memory_map_size = *args.channel.memory_map_size; | |
324 | shm_fd = *args.channel.shm_fd; | |
325 | wait_fd = *args.channel.wait_fd; | |
326 | break; | |
327 | case LTTNG_UST_TRACER_VERSION: | |
328 | lur.u.version = lum->u.version; | |
329 | break; | |
330 | case LTTNG_UST_TRACEPOINT_LIST_GET: | |
331 | memcpy(&lur.u.tracepoint, &lum->u.tracepoint, sizeof(lur.u.tracepoint)); | |
332 | break; | |
333 | } | |
381c0f1e | 334 | } |
46050b1a | 335 | ret = send_reply(sock, &lur); |
193183fb MD |
336 | if (ret < 0) { |
337 | perror("error sending reply"); | |
338 | goto error; | |
339 | } | |
46050b1a | 340 | |
824f40b8 MD |
341 | if ((lum->cmd == LTTNG_UST_STREAM |
342 | || lum->cmd == LTTNG_UST_CHANNEL | |
343 | || lum->cmd == LTTNG_UST_METADATA) | |
57773204 | 344 | && lur.ret_code == USTCOMM_OK) { |
5f003977 MD |
345 | int sendret = 0; |
346 | ||
381c0f1e | 347 | /* we also need to send the file descriptors. */ |
57773204 | 348 | ret = ustcomm_send_fds_unix_sock(sock, |
193183fb | 349 | &shm_fd, &shm_fd, |
381c0f1e MD |
350 | 1, sizeof(int)); |
351 | if (ret < 0) { | |
352 | perror("send shm_fd"); | |
5f003977 | 353 | sendret = ret; |
381c0f1e | 354 | } |
5f003977 MD |
355 | /* |
356 | * The sessiond expects 2 file descriptors, even upon | |
357 | * error. | |
358 | */ | |
57773204 | 359 | ret = ustcomm_send_fds_unix_sock(sock, |
193183fb | 360 | &wait_fd, &wait_fd, |
381c0f1e MD |
361 | 1, sizeof(int)); |
362 | if (ret < 0) { | |
363 | perror("send wait_fd"); | |
364 | goto error; | |
365 | } | |
5f003977 MD |
366 | if (sendret) { |
367 | ret = sendret; | |
368 | goto error; | |
369 | } | |
381c0f1e | 370 | } |
ef9ff354 MD |
371 | /* |
372 | * We still have the memory map reference, and the fds have been | |
3ad5f707 MD |
373 | * sent to the sessiond. We can therefore close those fds. Note |
374 | * that we keep the write side of the wait_fd open, but close | |
375 | * the read side. | |
ef9ff354 MD |
376 | */ |
377 | if (lur.ret_code == USTCOMM_OK) { | |
378 | switch (lum->cmd) { | |
379 | case LTTNG_UST_STREAM: | |
380 | if (shm_fd >= 0) { | |
381 | ret = close(shm_fd); | |
382 | if (ret) { | |
383 | PERROR("Error closing stream shm_fd"); | |
384 | } | |
385 | *args.stream.shm_fd = -1; | |
386 | } | |
387 | if (wait_fd >= 0) { | |
388 | ret = close(wait_fd); | |
389 | if (ret) { | |
390 | PERROR("Error closing stream wait_fd"); | |
391 | } | |
392 | *args.stream.wait_fd = -1; | |
393 | } | |
394 | break; | |
395 | case LTTNG_UST_METADATA: | |
396 | case LTTNG_UST_CHANNEL: | |
397 | if (shm_fd >= 0) { | |
398 | ret = close(shm_fd); | |
399 | if (ret) { | |
400 | PERROR("Error closing channel shm_fd"); | |
401 | } | |
402 | *args.channel.shm_fd = -1; | |
403 | } | |
404 | if (wait_fd >= 0) { | |
405 | ret = close(wait_fd); | |
406 | if (ret) { | |
407 | PERROR("Error closing channel wait_fd"); | |
408 | } | |
409 | *args.channel.wait_fd = -1; | |
410 | } | |
411 | break; | |
412 | } | |
413 | } | |
414 | ||
381c0f1e | 415 | error: |
17dfb34b | 416 | ust_unlock(); |
1ea11eab | 417 | return ret; |
d9e99d10 MD |
418 | } |
419 | ||
46050b1a | 420 | static |
efe0de09 | 421 | void cleanup_sock_info(struct sock_info *sock_info, int exiting) |
46050b1a MD |
422 | { |
423 | int ret; | |
424 | ||
425 | if (sock_info->socket != -1) { | |
e6973a89 | 426 | ret = ustcomm_close_unix_sock(sock_info->socket); |
46050b1a | 427 | if (ret) { |
7fc90dca | 428 | ERR("Error closing apps socket"); |
46050b1a MD |
429 | } |
430 | sock_info->socket = -1; | |
431 | } | |
432 | if (sock_info->root_handle != -1) { | |
d4419b81 | 433 | ret = lttng_ust_objd_unref(sock_info->root_handle); |
46050b1a MD |
434 | if (ret) { |
435 | ERR("Error unref root handle"); | |
436 | } | |
437 | sock_info->root_handle = -1; | |
438 | } | |
318dfea9 | 439 | sock_info->constructor_sem_posted = 0; |
efe0de09 MD |
440 | /* |
441 | * wait_shm_mmap is used by listener threads outside of the | |
442 | * ust lock, so we cannot tear it down ourselves, because we | |
443 | * cannot join on these threads. Leave this task to the OS | |
444 | * process exit. | |
445 | */ | |
446 | if (!exiting && sock_info->wait_shm_mmap) { | |
7fc90dca MD |
447 | ret = munmap(sock_info->wait_shm_mmap, sysconf(_SC_PAGE_SIZE)); |
448 | if (ret) { | |
449 | ERR("Error unmapping wait shm"); | |
450 | } | |
451 | sock_info->wait_shm_mmap = NULL; | |
452 | } | |
453 | } | |
454 | ||
58d4b2a2 | 455 | /* |
33bbeb90 MD |
456 | * Using fork to set umask in the child process (not multi-thread safe). |
457 | * We deal with the shm_open vs ftruncate race (happening when the | |
458 | * sessiond owns the shm and does not let everybody modify it, to ensure | |
459 | * safety against shm_unlink) by simply letting the mmap fail and | |
460 | * retrying after a few seconds. | |
461 | * For global shm, everybody has rw access to it until the sessiond | |
462 | * starts. | |
58d4b2a2 | 463 | */ |
7fc90dca | 464 | static |
58d4b2a2 | 465 | int get_wait_shm(struct sock_info *sock_info, size_t mmap_size) |
7fc90dca | 466 | { |
7fc90dca | 467 | int wait_shm_fd, ret; |
58d4b2a2 | 468 | pid_t pid; |
44e073f5 | 469 | |
58d4b2a2 | 470 | /* |
33bbeb90 | 471 | * Try to open read-only. |
58d4b2a2 | 472 | */ |
33bbeb90 | 473 | wait_shm_fd = shm_open(sock_info->wait_shm_path, O_RDONLY, 0); |
58d4b2a2 MD |
474 | if (wait_shm_fd >= 0) { |
475 | goto end; | |
476 | } else if (wait_shm_fd < 0 && errno != ENOENT) { | |
477 | /* | |
33bbeb90 MD |
478 | * Real-only open did not work, and it's not because the |
479 | * entry was not present. It's a failure that prohibits | |
480 | * using shm. | |
58d4b2a2 | 481 | */ |
7fc90dca | 482 | ERR("Error opening shm %s", sock_info->wait_shm_path); |
58d4b2a2 | 483 | goto end; |
7fc90dca MD |
484 | } |
485 | /* | |
58d4b2a2 MD |
486 | * If the open failed because the file did not exist, try |
487 | * creating it ourself. | |
7fc90dca | 488 | */ |
3b8b68e7 | 489 | lttng_ust_nest_count++; |
58d4b2a2 | 490 | pid = fork(); |
3b8b68e7 | 491 | lttng_ust_nest_count--; |
58d4b2a2 MD |
492 | if (pid > 0) { |
493 | int status; | |
494 | ||
495 | /* | |
496 | * Parent: wait for child to return, in which case the | |
497 | * shared memory map will have been created. | |
498 | */ | |
499 | pid = wait(&status); | |
b7d3cb32 | 500 | if (pid < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) { |
58d4b2a2 MD |
501 | wait_shm_fd = -1; |
502 | goto end; | |
7fc90dca | 503 | } |
58d4b2a2 MD |
504 | /* |
505 | * Try to open read-only again after creation. | |
506 | */ | |
33bbeb90 | 507 | wait_shm_fd = shm_open(sock_info->wait_shm_path, O_RDONLY, 0); |
58d4b2a2 MD |
508 | if (wait_shm_fd < 0) { |
509 | /* | |
510 | * Real-only open did not work. It's a failure | |
511 | * that prohibits using shm. | |
512 | */ | |
513 | ERR("Error opening shm %s", sock_info->wait_shm_path); | |
514 | goto end; | |
515 | } | |
516 | goto end; | |
517 | } else if (pid == 0) { | |
518 | int create_mode; | |
519 | ||
520 | /* Child */ | |
33bbeb90 | 521 | create_mode = S_IRUSR | S_IWUSR | S_IRGRP; |
58d4b2a2 | 522 | if (sock_info->global) |
33bbeb90 | 523 | create_mode |= S_IROTH | S_IWGRP | S_IWOTH; |
58d4b2a2 MD |
524 | /* |
525 | * We're alone in a child process, so we can modify the | |
526 | * process-wide umask. | |
527 | */ | |
33bbeb90 | 528 | umask(~create_mode); |
58d4b2a2 | 529 | /* |
33bbeb90 MD |
530 | * Try creating shm (or get rw access). |
531 | * We don't do an exclusive open, because we allow other | |
532 | * processes to create+ftruncate it concurrently. | |
58d4b2a2 MD |
533 | */ |
534 | wait_shm_fd = shm_open(sock_info->wait_shm_path, | |
535 | O_RDWR | O_CREAT, create_mode); | |
536 | if (wait_shm_fd >= 0) { | |
537 | ret = ftruncate(wait_shm_fd, mmap_size); | |
538 | if (ret) { | |
539 | PERROR("ftruncate"); | |
c0872615 | 540 | _exit(EXIT_FAILURE); |
58d4b2a2 | 541 | } |
c0872615 | 542 | _exit(EXIT_SUCCESS); |
58d4b2a2 | 543 | } |
33bbeb90 MD |
544 | /* |
545 | * For local shm, we need to have rw access to accept | |
546 | * opening it: this means the local sessiond will be | |
547 | * able to wake us up. For global shm, we open it even | |
548 | * if rw access is not granted, because the root.root | |
549 | * sessiond will be able to override all rights and wake | |
550 | * us up. | |
551 | */ | |
552 | if (!sock_info->global && errno != EACCES) { | |
58d4b2a2 | 553 | ERR("Error opening shm %s", sock_info->wait_shm_path); |
63375cce | 554 | _exit(EXIT_FAILURE); |
58d4b2a2 MD |
555 | } |
556 | /* | |
33bbeb90 MD |
557 | * The shm exists, but we cannot open it RW. Report |
558 | * success. | |
58d4b2a2 | 559 | */ |
63375cce | 560 | _exit(EXIT_SUCCESS); |
58d4b2a2 MD |
561 | } else { |
562 | return -1; | |
7fc90dca | 563 | } |
58d4b2a2 | 564 | end: |
33bbeb90 MD |
565 | if (wait_shm_fd >= 0 && !sock_info->global) { |
566 | struct stat statbuf; | |
567 | ||
568 | /* | |
569 | * Ensure that our user is the owner of the shm file for | |
570 | * local shm. If we do not own the file, it means our | |
571 | * sessiond will not have access to wake us up (there is | |
572 | * probably a rogue process trying to fake our | |
573 | * sessiond). Fallback to polling method in this case. | |
574 | */ | |
575 | ret = fstat(wait_shm_fd, &statbuf); | |
576 | if (ret) { | |
577 | PERROR("fstat"); | |
578 | goto error_close; | |
579 | } | |
580 | if (statbuf.st_uid != getuid()) | |
581 | goto error_close; | |
582 | } | |
58d4b2a2 | 583 | return wait_shm_fd; |
33bbeb90 MD |
584 | |
585 | error_close: | |
586 | ret = close(wait_shm_fd); | |
587 | if (ret) { | |
588 | PERROR("Error closing fd"); | |
589 | } | |
590 | return -1; | |
58d4b2a2 MD |
591 | } |
592 | ||
593 | static | |
594 | char *get_map_shm(struct sock_info *sock_info) | |
595 | { | |
596 | size_t mmap_size = sysconf(_SC_PAGE_SIZE); | |
597 | int wait_shm_fd, ret; | |
598 | char *wait_shm_mmap; | |
599 | ||
600 | wait_shm_fd = get_wait_shm(sock_info, mmap_size); | |
601 | if (wait_shm_fd < 0) { | |
602 | goto error; | |
44e073f5 | 603 | } |
7fc90dca MD |
604 | wait_shm_mmap = mmap(NULL, mmap_size, PROT_READ, |
605 | MAP_SHARED, wait_shm_fd, 0); | |
7fc90dca MD |
606 | /* close shm fd immediately after taking the mmap reference */ |
607 | ret = close(wait_shm_fd); | |
608 | if (ret) { | |
33bbeb90 MD |
609 | PERROR("Error closing fd"); |
610 | } | |
611 | if (wait_shm_mmap == MAP_FAILED) { | |
612 | DBG("mmap error (can be caused by race with sessiond). Fallback to poll mode."); | |
613 | goto error; | |
7fc90dca MD |
614 | } |
615 | return wait_shm_mmap; | |
616 | ||
617 | error: | |
618 | return NULL; | |
619 | } | |
620 | ||
621 | static | |
622 | void wait_for_sessiond(struct sock_info *sock_info) | |
623 | { | |
efe0de09 | 624 | int ret; |
80e2814b | 625 | |
7fc90dca MD |
626 | ust_lock(); |
627 | if (lttng_ust_comm_should_quit) { | |
628 | goto quit; | |
629 | } | |
37ed587a MD |
630 | if (wait_poll_fallback) { |
631 | goto error; | |
632 | } | |
7fc90dca MD |
633 | if (!sock_info->wait_shm_mmap) { |
634 | sock_info->wait_shm_mmap = get_map_shm(sock_info); | |
635 | if (!sock_info->wait_shm_mmap) | |
636 | goto error; | |
637 | } | |
638 | ust_unlock(); | |
639 | ||
640 | DBG("Waiting for %s apps sessiond", sock_info->name); | |
80e2814b MD |
641 | /* Wait for futex wakeup */ |
642 | if (uatomic_read((int32_t *) sock_info->wait_shm_mmap) == 0) { | |
643 | ret = futex_async((int32_t *) sock_info->wait_shm_mmap, | |
644 | FUTEX_WAIT, 0, NULL, NULL, 0); | |
80e2814b | 645 | if (ret < 0) { |
37ed587a MD |
646 | if (errno == EFAULT) { |
647 | wait_poll_fallback = 1; | |
a8b870ad | 648 | DBG( |
37ed587a MD |
649 | "Linux kernels 2.6.33 to 3.0 (with the exception of stable versions) " |
650 | "do not support FUTEX_WAKE on read-only memory mappings correctly. " | |
651 | "Please upgrade your kernel " | |
652 | "(fix is commit 9ea71503a8ed9184d2d0b8ccc4d269d05f7940ae in Linux kernel " | |
653 | "mainline). LTTng-UST will use polling mode fallback."); | |
cd27263b MD |
654 | if (ust_debug()) |
655 | PERROR("futex"); | |
37ed587a | 656 | } |
80e2814b MD |
657 | } |
658 | } | |
7fc90dca MD |
659 | return; |
660 | ||
661 | quit: | |
662 | ust_unlock(); | |
663 | return; | |
664 | ||
665 | error: | |
666 | ust_unlock(); | |
7fc90dca | 667 | return; |
46050b1a MD |
668 | } |
669 | ||
1ea11eab MD |
670 | /* |
671 | * This thread does not allocate any resource, except within | |
672 | * handle_message, within mutex protection. This mutex protects against | |
673 | * fork and exit. | |
674 | * The other moment it allocates resources is at socket connexion, which | |
675 | * is also protected by the mutex. | |
676 | */ | |
d9e99d10 MD |
677 | static |
678 | void *ust_listener_thread(void *arg) | |
679 | { | |
1ea11eab | 680 | struct sock_info *sock_info = arg; |
c0eedf81 | 681 | int sock, ret, prev_connect_failed = 0, has_waited = 0; |
d9e99d10 | 682 | |
9eb62b9c MD |
683 | /* Restart trying to connect to the session daemon */ |
684 | restart: | |
c0eedf81 MD |
685 | if (prev_connect_failed) { |
686 | /* Wait for sessiond availability with pipe */ | |
687 | wait_for_sessiond(sock_info); | |
688 | if (has_waited) { | |
689 | has_waited = 0; | |
690 | /* | |
691 | * Sleep for 5 seconds before retrying after a | |
692 | * sequence of failure / wait / failure. This | |
693 | * deals with a killed or broken session daemon. | |
694 | */ | |
695 | sleep(5); | |
696 | } | |
697 | has_waited = 1; | |
698 | prev_connect_failed = 0; | |
699 | } | |
17dfb34b | 700 | ust_lock(); |
1ea11eab MD |
701 | |
702 | if (lttng_ust_comm_should_quit) { | |
17dfb34b | 703 | ust_unlock(); |
1ea11eab MD |
704 | goto quit; |
705 | } | |
9eb62b9c | 706 | |
1ea11eab | 707 | if (sock_info->socket != -1) { |
e6973a89 | 708 | ret = ustcomm_close_unix_sock(sock_info->socket); |
1ea11eab | 709 | if (ret) { |
11ff9c7d | 710 | ERR("Error closing %s apps socket", sock_info->name); |
1ea11eab MD |
711 | } |
712 | sock_info->socket = -1; | |
713 | } | |
46050b1a | 714 | |
9eb62b9c | 715 | /* Register */ |
57773204 | 716 | ret = ustcomm_connect_unix_sock(sock_info->sock_path); |
9eb62b9c | 717 | if (ret < 0) { |
4d3c9523 | 718 | DBG("Info: sessiond not accepting connections to %s apps socket", sock_info->name); |
c0eedf81 | 719 | prev_connect_failed = 1; |
11ff9c7d MD |
720 | /* |
721 | * If we cannot find the sessiond daemon, don't delay | |
722 | * constructor execution. | |
723 | */ | |
edaa1431 | 724 | ret = handle_register_done(sock_info); |
11ff9c7d | 725 | assert(!ret); |
17dfb34b | 726 | ust_unlock(); |
1ea11eab | 727 | goto restart; |
46050b1a MD |
728 | } |
729 | ||
730 | sock_info->socket = sock = ret; | |
731 | ||
732 | /* | |
733 | * Create only one root handle per listener thread for the whole | |
734 | * process lifetime. | |
735 | */ | |
736 | if (sock_info->root_handle == -1) { | |
737 | ret = lttng_abi_create_root_handle(); | |
a51070bb | 738 | if (ret < 0) { |
46050b1a | 739 | ERR("Error creating root handle"); |
17dfb34b | 740 | ust_unlock(); |
46050b1a MD |
741 | goto quit; |
742 | } | |
743 | sock_info->root_handle = ret; | |
9eb62b9c | 744 | } |
1ea11eab | 745 | |
9eb62b9c MD |
746 | ret = register_app_to_sessiond(sock); |
747 | if (ret < 0) { | |
11ff9c7d | 748 | ERR("Error registering to %s apps socket", sock_info->name); |
c0eedf81 | 749 | prev_connect_failed = 1; |
11ff9c7d MD |
750 | /* |
751 | * If we cannot register to the sessiond daemon, don't | |
752 | * delay constructor execution. | |
753 | */ | |
edaa1431 | 754 | ret = handle_register_done(sock_info); |
11ff9c7d | 755 | assert(!ret); |
17dfb34b | 756 | ust_unlock(); |
9eb62b9c MD |
757 | goto restart; |
758 | } | |
17dfb34b | 759 | ust_unlock(); |
46050b1a | 760 | |
d9e99d10 MD |
761 | for (;;) { |
762 | ssize_t len; | |
57773204 | 763 | struct ustcomm_ust_msg lum; |
d9e99d10 | 764 | |
57773204 | 765 | len = ustcomm_recv_unix_sock(sock, &lum, sizeof(lum)); |
d9e99d10 MD |
766 | switch (len) { |
767 | case 0: /* orderly shutdown */ | |
11ff9c7d | 768 | DBG("%s ltt-sessiond has performed an orderly shutdown\n", sock_info->name); |
8236ba10 MD |
769 | ust_lock(); |
770 | /* | |
771 | * Either sessiond has shutdown or refused us by closing the socket. | |
772 | * In either case, we don't want to delay construction execution, | |
773 | * and we need to wait before retry. | |
774 | */ | |
775 | prev_connect_failed = 1; | |
776 | /* | |
777 | * If we cannot register to the sessiond daemon, don't | |
778 | * delay constructor execution. | |
779 | */ | |
780 | ret = handle_register_done(sock_info); | |
781 | assert(!ret); | |
782 | ust_unlock(); | |
d9e99d10 | 783 | goto end; |
e7723462 | 784 | case sizeof(lum): |
d9e99d10 | 785 | DBG("message received\n"); |
11ff9c7d | 786 | ret = handle_message(sock_info, sock, &lum); |
2a80c9d8 | 787 | if (ret < 0) { |
11ff9c7d | 788 | ERR("Error handling message for %s socket", sock_info->name); |
d9e99d10 MD |
789 | } |
790 | continue; | |
791 | case -1: | |
8236ba10 | 792 | DBG("Receive failed from lttng-sessiond with errno %d", errno); |
d9e99d10 | 793 | if (errno == ECONNRESET) { |
11ff9c7d | 794 | ERR("%s remote end closed connection\n", sock_info->name); |
d9e99d10 MD |
795 | goto end; |
796 | } | |
797 | goto end; | |
798 | default: | |
11ff9c7d | 799 | ERR("incorrect message size (%s socket): %zd\n", sock_info->name, len); |
d9e99d10 MD |
800 | continue; |
801 | } | |
802 | ||
803 | } | |
804 | end: | |
9eb62b9c | 805 | goto restart; /* try to reconnect */ |
1ea11eab | 806 | quit: |
d9e99d10 MD |
807 | return NULL; |
808 | } | |
809 | ||
cf12a773 MD |
810 | /* |
811 | * Return values: -1: don't wait. 0: wait forever. 1: timeout wait. | |
812 | */ | |
11ff9c7d MD |
813 | static |
814 | int get_timeout(struct timespec *constructor_timeout) | |
815 | { | |
cf12a773 MD |
816 | long constructor_delay_ms = LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS; |
817 | char *str_delay; | |
11ff9c7d MD |
818 | int ret; |
819 | ||
69400ac4 | 820 | str_delay = getenv("LTTNG_UST_REGISTER_TIMEOUT"); |
cf12a773 MD |
821 | if (str_delay) { |
822 | constructor_delay_ms = strtol(str_delay, NULL, 10); | |
823 | } | |
824 | ||
825 | switch (constructor_delay_ms) { | |
826 | case -1:/* fall-through */ | |
827 | case 0: | |
828 | return constructor_delay_ms; | |
829 | default: | |
830 | break; | |
831 | } | |
832 | ||
833 | /* | |
834 | * If we are unable to find the current time, don't wait. | |
835 | */ | |
836 | ret = clock_gettime(CLOCK_REALTIME, constructor_timeout); | |
837 | if (ret) { | |
838 | return -1; | |
839 | } | |
95259bd0 MD |
840 | constructor_timeout->tv_sec += constructor_delay_ms / 1000UL; |
841 | constructor_timeout->tv_nsec += | |
842 | (constructor_delay_ms % 1000UL) * 1000000UL; | |
11ff9c7d MD |
843 | if (constructor_timeout->tv_nsec >= 1000000000UL) { |
844 | constructor_timeout->tv_sec++; | |
845 | constructor_timeout->tv_nsec -= 1000000000UL; | |
846 | } | |
cf12a773 | 847 | return 1; |
11ff9c7d | 848 | } |
d9e99d10 | 849 | |
2691221a MD |
850 | /* |
851 | * sessiond monitoring thread: monitor presence of global and per-user | |
852 | * sessiond by polling the application common named pipe. | |
853 | */ | |
854 | /* TODO */ | |
855 | ||
edaa1431 | 856 | void __attribute__((constructor)) lttng_ust_init(void) |
2691221a | 857 | { |
11ff9c7d | 858 | struct timespec constructor_timeout; |
e32d20e9 | 859 | sigset_t sig_all_blocked, orig_parent_mask; |
e63683c7 | 860 | pthread_attr_t thread_attr; |
cf12a773 | 861 | int timeout_mode; |
2691221a MD |
862 | int ret; |
863 | ||
edaa1431 MD |
864 | if (uatomic_xchg(&initialized, 1) == 1) |
865 | return; | |
866 | ||
eddd8d5d MD |
867 | /* |
868 | * Fixup interdependency between TLS fixup mutex (which happens | |
869 | * to be the dynamic linker mutex) and ust_lock, taken within | |
870 | * the ust lock. | |
871 | */ | |
872 | lttng_fixup_event_tls(); | |
f645cfa7 | 873 | lttng_fixup_ringbuffer_tls(); |
4158a15a | 874 | lttng_fixup_vtid_tls(); |
e38c8fc1 | 875 | lttng_fixup_nest_count_tls(); |
eddd8d5d | 876 | |
edaa1431 MD |
877 | /* |
878 | * We want precise control over the order in which we construct | |
879 | * our sub-libraries vs starting to receive commands from | |
880 | * sessiond (otherwise leading to errors when trying to create | |
881 | * sessiond before the init functions are completed). | |
882 | */ | |
2691221a | 883 | init_usterr(); |
edaa1431 MD |
884 | init_tracepoint(); |
885 | ltt_ring_buffer_metadata_client_init(); | |
886 | ltt_ring_buffer_client_overwrite_init(); | |
887 | ltt_ring_buffer_client_discard_init(); | |
2691221a | 888 | |
cf12a773 | 889 | timeout_mode = get_timeout(&constructor_timeout); |
11ff9c7d | 890 | |
95259bd0 | 891 | ret = sem_init(&constructor_wait, 0, 0); |
11ff9c7d MD |
892 | assert(!ret); |
893 | ||
8d20bf54 | 894 | ret = setup_local_apps(); |
2691221a | 895 | if (ret) { |
e699eda9 | 896 | DBG("local apps setup returned %d", ret); |
2691221a | 897 | } |
e32d20e9 WP |
898 | |
899 | /* A new thread created by pthread_create inherits the signal mask | |
900 | * from the parent. To avoid any signal being received by the | |
901 | * listener thread, we block all signals temporarily in the parent, | |
902 | * while we create the listener thread. | |
903 | */ | |
904 | sigfillset(&sig_all_blocked); | |
905 | ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_parent_mask); | |
906 | if (ret) { | |
e37047b6 | 907 | ERR("pthread_sigmask: %s", strerror(ret)); |
e32d20e9 WP |
908 | } |
909 | ||
e63683c7 MG |
910 | ret = pthread_attr_init(&thread_attr); |
911 | if (ret) { | |
912 | ERR("pthread_attr_init: %s", strerror(ret)); | |
913 | } | |
914 | ret = pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_DETACHED); | |
915 | if (ret) { | |
916 | ERR("pthread_attr_setdetachstate: %s", strerror(ret)); | |
917 | } | |
918 | ||
919 | ret = pthread_create(&global_apps.ust_listener, &thread_attr, | |
dc43c97f | 920 | ust_listener_thread, &global_apps); |
e37047b6 MD |
921 | if (ret) { |
922 | ERR("pthread_create global: %s", strerror(ret)); | |
923 | } | |
8d20bf54 | 924 | if (local_apps.allowed) { |
e63683c7 | 925 | ret = pthread_create(&local_apps.ust_listener, &thread_attr, |
dc43c97f | 926 | ust_listener_thread, &local_apps); |
e37047b6 MD |
927 | if (ret) { |
928 | ERR("pthread_create local: %s", strerror(ret)); | |
929 | } | |
8d20bf54 MD |
930 | } else { |
931 | handle_register_done(&local_apps); | |
932 | } | |
e63683c7 MG |
933 | ret = pthread_attr_destroy(&thread_attr); |
934 | if (ret) { | |
935 | ERR("pthread_attr_destroy: %s", strerror(ret)); | |
936 | } | |
8d20bf54 | 937 | |
e32d20e9 WP |
938 | /* Restore original signal mask in parent */ |
939 | ret = pthread_sigmask(SIG_SETMASK, &orig_parent_mask, NULL); | |
940 | if (ret) { | |
e37047b6 | 941 | ERR("pthread_sigmask: %s", strerror(ret)); |
e32d20e9 WP |
942 | } |
943 | ||
cf12a773 MD |
944 | switch (timeout_mode) { |
945 | case 1: /* timeout wait */ | |
95259bd0 MD |
946 | do { |
947 | ret = sem_timedwait(&constructor_wait, | |
948 | &constructor_timeout); | |
949 | } while (ret < 0 && errno == EINTR); | |
cf12a773 MD |
950 | if (ret < 0 && errno == ETIMEDOUT) { |
951 | ERR("Timed out waiting for ltt-sessiond"); | |
952 | } else { | |
953 | assert(!ret); | |
954 | } | |
955 | break; | |
7b766b16 | 956 | case -1:/* wait forever */ |
95259bd0 MD |
957 | do { |
958 | ret = sem_wait(&constructor_wait); | |
959 | } while (ret < 0 && errno == EINTR); | |
11ff9c7d | 960 | assert(!ret); |
cf12a773 | 961 | break; |
7b766b16 | 962 | case 0: /* no timeout */ |
cf12a773 | 963 | break; |
11ff9c7d | 964 | } |
2691221a MD |
965 | } |
966 | ||
17dfb34b MD |
967 | static |
968 | void lttng_ust_cleanup(int exiting) | |
969 | { | |
efe0de09 | 970 | cleanup_sock_info(&global_apps, exiting); |
17dfb34b | 971 | if (local_apps.allowed) { |
efe0de09 | 972 | cleanup_sock_info(&local_apps, exiting); |
17dfb34b | 973 | } |
efe0de09 MD |
974 | /* |
975 | * The teardown in this function all affect data structures | |
976 | * accessed under the UST lock by the listener thread. This | |
977 | * lock, along with the lttng_ust_comm_should_quit flag, ensure | |
978 | * that none of these threads are accessing this data at this | |
979 | * point. | |
980 | */ | |
17dfb34b | 981 | lttng_ust_abi_exit(); |
003fedf4 | 982 | lttng_ust_events_exit(); |
17dfb34b MD |
983 | ltt_ring_buffer_client_discard_exit(); |
984 | ltt_ring_buffer_client_overwrite_exit(); | |
985 | ltt_ring_buffer_metadata_client_exit(); | |
986 | exit_tracepoint(); | |
987 | if (!exiting) { | |
988 | /* Reinitialize values for fork */ | |
989 | sem_count = 2; | |
990 | lttng_ust_comm_should_quit = 0; | |
991 | initialized = 0; | |
992 | } | |
993 | } | |
994 | ||
edaa1431 | 995 | void __attribute__((destructor)) lttng_ust_exit(void) |
2691221a MD |
996 | { |
997 | int ret; | |
998 | ||
9eb62b9c MD |
999 | /* |
1000 | * Using pthread_cancel here because: | |
1001 | * A) we don't want to hang application teardown. | |
1002 | * B) the thread is not allocating any resource. | |
1003 | */ | |
1ea11eab MD |
1004 | |
1005 | /* | |
1006 | * Require the communication thread to quit. Synchronize with | |
1007 | * mutexes to ensure it is not in a mutex critical section when | |
1008 | * pthread_cancel is later called. | |
1009 | */ | |
17dfb34b | 1010 | ust_lock(); |
1ea11eab | 1011 | lttng_ust_comm_should_quit = 1; |
17dfb34b | 1012 | ust_unlock(); |
1ea11eab | 1013 | |
f5f94532 | 1014 | /* cancel threads */ |
1ea11eab | 1015 | ret = pthread_cancel(global_apps.ust_listener); |
9eb62b9c | 1016 | if (ret) { |
e37047b6 MD |
1017 | ERR("Error cancelling global ust listener thread: %s", |
1018 | strerror(ret)); | |
2691221a | 1019 | } |
8d20bf54 MD |
1020 | if (local_apps.allowed) { |
1021 | ret = pthread_cancel(local_apps.ust_listener); | |
1022 | if (ret) { | |
e37047b6 MD |
1023 | ERR("Error cancelling local ust listener thread: %s", |
1024 | strerror(ret)); | |
8d20bf54 | 1025 | } |
8d20bf54 | 1026 | } |
efe0de09 MD |
1027 | /* |
1028 | * Do NOT join threads: use of sys_futex makes it impossible to | |
1029 | * join the threads without using async-cancel, but async-cancel | |
1030 | * is delivered by a signal, which could hit the target thread | |
1031 | * anywhere in its code path, including while the ust_lock() is | |
1032 | * held, causing a deadlock for the other thread. Let the OS | |
1033 | * cleanup the threads if there are stalled in a syscall. | |
1034 | */ | |
17dfb34b | 1035 | lttng_ust_cleanup(1); |
2691221a | 1036 | } |
e822f505 MD |
1037 | |
1038 | /* | |
1039 | * We exclude the worker threads across fork and clone (except | |
1040 | * CLONE_VM), because these system calls only keep the forking thread | |
1041 | * running in the child. Therefore, we don't want to call fork or clone | |
1042 | * in the middle of an tracepoint or ust tracing state modification. | |
1043 | * Holding this mutex protects these structures across fork and clone. | |
1044 | */ | |
b728d87e | 1045 | void ust_before_fork(sigset_t *save_sigset) |
e822f505 MD |
1046 | { |
1047 | /* | |
1048 | * Disable signals. This is to avoid that the child intervenes | |
1049 | * before it is properly setup for tracing. It is safer to | |
1050 | * disable all signals, because then we know we are not breaking | |
1051 | * anything by restoring the original mask. | |
1052 | */ | |
1053 | sigset_t all_sigs; | |
1054 | int ret; | |
1055 | ||
3b8b68e7 MD |
1056 | if (lttng_ust_nest_count) |
1057 | return; | |
e822f505 MD |
1058 | /* Disable signals */ |
1059 | sigfillset(&all_sigs); | |
b728d87e | 1060 | ret = sigprocmask(SIG_BLOCK, &all_sigs, save_sigset); |
e822f505 MD |
1061 | if (ret == -1) { |
1062 | PERROR("sigprocmask"); | |
1063 | } | |
17dfb34b | 1064 | ust_lock(); |
e822f505 MD |
1065 | rcu_bp_before_fork(); |
1066 | } | |
1067 | ||
b728d87e | 1068 | static void ust_after_fork_common(sigset_t *restore_sigset) |
e822f505 MD |
1069 | { |
1070 | int ret; | |
1071 | ||
17dfb34b MD |
1072 | DBG("process %d", getpid()); |
1073 | ust_unlock(); | |
e822f505 | 1074 | /* Restore signals */ |
23c8854a | 1075 | ret = sigprocmask(SIG_SETMASK, restore_sigset, NULL); |
e822f505 MD |
1076 | if (ret == -1) { |
1077 | PERROR("sigprocmask"); | |
1078 | } | |
1079 | } | |
1080 | ||
b728d87e | 1081 | void ust_after_fork_parent(sigset_t *restore_sigset) |
e822f505 | 1082 | { |
3b8b68e7 MD |
1083 | if (lttng_ust_nest_count) |
1084 | return; | |
17dfb34b | 1085 | DBG("process %d", getpid()); |
e822f505 MD |
1086 | rcu_bp_after_fork_parent(); |
1087 | /* Release mutexes and reenable signals */ | |
b728d87e | 1088 | ust_after_fork_common(restore_sigset); |
e822f505 MD |
1089 | } |
1090 | ||
17dfb34b MD |
1091 | /* |
1092 | * After fork, in the child, we need to cleanup all the leftover state, | |
1093 | * except the worker thread which already magically disappeared thanks | |
1094 | * to the weird Linux fork semantics. After tyding up, we call | |
1095 | * lttng_ust_init() again to start over as a new PID. | |
1096 | * | |
1097 | * This is meant for forks() that have tracing in the child between the | |
1098 | * fork and following exec call (if there is any). | |
1099 | */ | |
b728d87e | 1100 | void ust_after_fork_child(sigset_t *restore_sigset) |
e822f505 | 1101 | { |
3b8b68e7 MD |
1102 | if (lttng_ust_nest_count) |
1103 | return; | |
17dfb34b | 1104 | DBG("process %d", getpid()); |
e822f505 MD |
1105 | /* Release urcu mutexes */ |
1106 | rcu_bp_after_fork_child(); | |
17dfb34b | 1107 | lttng_ust_cleanup(0); |
a93bfc45 | 1108 | lttng_context_vtid_reset(); |
e822f505 | 1109 | /* Release mutexes and reenable signals */ |
b728d87e | 1110 | ust_after_fork_common(restore_sigset); |
318dfea9 | 1111 | lttng_ust_init(); |
e822f505 | 1112 | } |