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> | |
7fc90dca MD |
25 | #include <sys/mman.h> |
26 | #include <sys/stat.h> | |
58d4b2a2 MD |
27 | #include <sys/types.h> |
28 | #include <sys/wait.h> | |
7fc90dca | 29 | #include <fcntl.h> |
2691221a MD |
30 | #include <unistd.h> |
31 | #include <errno.h> | |
d9e99d10 | 32 | #include <pthread.h> |
11ff9c7d MD |
33 | #include <semaphore.h> |
34 | #include <time.h> | |
1ea11eab | 35 | #include <assert.h> |
e822f505 | 36 | #include <signal.h> |
95259bd0 | 37 | #include <urcu/uatomic.h> |
80e2814b | 38 | #include <urcu/futex.h> |
c117fb1b | 39 | #include <urcu/compiler.h> |
1ea11eab | 40 | |
4318ae1b | 41 | #include <lttng/ust-events.h> |
4318ae1b | 42 | #include <lttng/ust-abi.h> |
4318ae1b | 43 | #include <lttng/ust.h> |
44c72f10 MD |
44 | #include <ust-comm.h> |
45 | #include <usterr-signal-safe.h> | |
46 | #include "tracepoint-internal.h" | |
b751f722 | 47 | #include "ltt-tracer-core.h" |
69df1193 | 48 | #include "compat.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; | |
180 | struct { | |
e44418f3 MD |
181 | uint32_t major; |
182 | uint32_t minor; | |
2691221a | 183 | pid_t pid; |
5c33bde8 | 184 | pid_t ppid; |
2691221a | 185 | uid_t uid; |
83610856 | 186 | gid_t gid; |
c117fb1b | 187 | uint32_t bits_per_long; |
2629549e | 188 | char name[16]; /* process name */ |
2691221a MD |
189 | } reg_msg; |
190 | ||
e44418f3 MD |
191 | reg_msg.major = LTTNG_UST_COMM_VERSION_MAJOR; |
192 | reg_msg.minor = LTTNG_UST_COMM_VERSION_MINOR; | |
2691221a | 193 | reg_msg.pid = getpid(); |
5c33bde8 | 194 | reg_msg.ppid = getppid(); |
2691221a | 195 | reg_msg.uid = getuid(); |
83610856 | 196 | reg_msg.gid = getgid(); |
c117fb1b | 197 | reg_msg.bits_per_long = CAA_BITS_PER_LONG; |
69df1193 | 198 | lttng_ust_getprocname(reg_msg.name); |
2691221a | 199 | |
57773204 | 200 | ret = ustcomm_send_unix_sock(socket, ®_msg, sizeof(reg_msg)); |
2691221a MD |
201 | if (ret >= 0 && ret != sizeof(reg_msg)) |
202 | return -EIO; | |
203 | return ret; | |
204 | } | |
205 | ||
d9e99d10 | 206 | static |
57773204 | 207 | int send_reply(int sock, struct ustcomm_ust_reply *lur) |
d9e99d10 | 208 | { |
9eb62b9c | 209 | ssize_t len; |
d3a492d1 | 210 | |
57773204 | 211 | len = ustcomm_send_unix_sock(sock, lur, sizeof(*lur)); |
d3a492d1 | 212 | switch (len) { |
a4be8962 | 213 | case sizeof(*lur): |
d3a492d1 MD |
214 | DBG("message successfully sent"); |
215 | return 0; | |
216 | case -1: | |
217 | if (errno == ECONNRESET) { | |
218 | printf("remote end closed connection\n"); | |
219 | return 0; | |
220 | } | |
221 | return -1; | |
222 | default: | |
223 | printf("incorrect message size: %zd\n", len); | |
224 | return -1; | |
225 | } | |
226 | } | |
227 | ||
228 | static | |
edaa1431 | 229 | int handle_register_done(struct sock_info *sock_info) |
11ff9c7d MD |
230 | { |
231 | int ret; | |
232 | ||
edaa1431 MD |
233 | if (sock_info->constructor_sem_posted) |
234 | return 0; | |
235 | sock_info->constructor_sem_posted = 1; | |
56cd7e2f MD |
236 | if (uatomic_read(&sem_count) <= 0) { |
237 | return 0; | |
238 | } | |
95259bd0 MD |
239 | ret = uatomic_add_return(&sem_count, -1); |
240 | if (ret == 0) { | |
241 | ret = sem_post(&constructor_wait); | |
242 | assert(!ret); | |
243 | } | |
11ff9c7d MD |
244 | return 0; |
245 | } | |
246 | ||
247 | static | |
248 | int handle_message(struct sock_info *sock_info, | |
57773204 | 249 | int sock, struct ustcomm_ust_msg *lum) |
d3a492d1 | 250 | { |
1ea11eab | 251 | int ret = 0; |
b61ce3b2 | 252 | const struct lttng_ust_objd_ops *ops; |
57773204 | 253 | struct ustcomm_ust_reply lur; |
193183fb | 254 | int shm_fd, wait_fd; |
bf5ff35e | 255 | char *shm_path, *wait_pipe_path; |
ef9ff354 | 256 | union ust_args args; |
1ea11eab | 257 | |
17dfb34b | 258 | ust_lock(); |
1ea11eab | 259 | |
46050b1a MD |
260 | memset(&lur, 0, sizeof(lur)); |
261 | ||
1ea11eab | 262 | if (lttng_ust_comm_should_quit) { |
46050b1a | 263 | ret = -EPERM; |
1ea11eab MD |
264 | goto end; |
265 | } | |
9eb62b9c | 266 | |
46050b1a MD |
267 | ops = objd_ops(lum->handle); |
268 | if (!ops) { | |
269 | ret = -ENOENT; | |
270 | goto end; | |
1ea11eab | 271 | } |
46050b1a MD |
272 | |
273 | switch (lum->cmd) { | |
11ff9c7d MD |
274 | case LTTNG_UST_REGISTER_DONE: |
275 | if (lum->handle == LTTNG_UST_ROOT_HANDLE) | |
edaa1431 | 276 | ret = handle_register_done(sock_info); |
11ff9c7d MD |
277 | else |
278 | ret = -EINVAL; | |
279 | break; | |
46050b1a MD |
280 | case LTTNG_UST_RELEASE: |
281 | if (lum->handle == LTTNG_UST_ROOT_HANDLE) | |
282 | ret = -EPERM; | |
283 | else | |
d4419b81 | 284 | ret = lttng_ust_objd_unref(lum->handle); |
d9e99d10 MD |
285 | break; |
286 | default: | |
46050b1a MD |
287 | if (ops->cmd) |
288 | ret = ops->cmd(lum->handle, lum->cmd, | |
ef9ff354 MD |
289 | (unsigned long) &lum->u, |
290 | &args); | |
46050b1a MD |
291 | else |
292 | ret = -ENOSYS; | |
293 | break; | |
d9e99d10 | 294 | } |
46050b1a | 295 | |
1ea11eab | 296 | end: |
46050b1a MD |
297 | lur.handle = lum->handle; |
298 | lur.cmd = lum->cmd; | |
299 | lur.ret_val = ret; | |
300 | if (ret >= 0) { | |
57773204 | 301 | lur.ret_code = USTCOMM_OK; |
46050b1a | 302 | } else { |
57773204 | 303 | //lur.ret_code = USTCOMM_SESSION_FAIL; |
193183fb | 304 | lur.ret_code = ret; |
46050b1a | 305 | } |
e6ea14c5 MD |
306 | if (ret >= 0) { |
307 | switch (lum->cmd) { | |
308 | case LTTNG_UST_STREAM: | |
309 | /* | |
310 | * Special-case reply to send stream info. | |
311 | * Use lum.u output. | |
312 | */ | |
313 | lur.u.stream.memory_map_size = *args.stream.memory_map_size; | |
bf5ff35e CB |
314 | shm_fd = *args.stream.shm_fd; |
315 | shm_path = args.stream.shm_path; | |
316 | wait_fd = *args.stream.wait_fd; | |
317 | wait_pipe_path = args.stream.wait_pipe_path; | |
e6ea14c5 MD |
318 | break; |
319 | case LTTNG_UST_METADATA: | |
320 | case LTTNG_UST_CHANNEL: | |
321 | lur.u.channel.memory_map_size = *args.channel.memory_map_size; | |
bf5ff35e CB |
322 | shm_fd = *args.channel.shm_fd; |
323 | shm_path = args.channel.shm_path; | |
324 | wait_fd = *args.channel.wait_fd; | |
325 | wait_pipe_path = args.channel.wait_pipe_path; | |
e6ea14c5 MD |
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 | ||
bf5ff35e CB |
347 | /* send the shm path */ |
348 | ret = ustcomm_send_string(sock, shm_path, strlen(shm_path)); | |
381c0f1e | 349 | if (ret < 0) { |
bf5ff35e | 350 | perror("send shm_path"); |
5f003977 | 351 | sendret = ret; |
381c0f1e | 352 | } |
5f003977 MD |
353 | /* |
354 | * The sessiond expects 2 file descriptors, even upon | |
355 | * error. | |
356 | */ | |
bf5ff35e | 357 | ret = ustcomm_send_string(sock, wait_pipe_path, strlen(wait_pipe_path)); |
381c0f1e | 358 | if (ret < 0) { |
bf5ff35e | 359 | perror("send wait_pipe_path"); |
381c0f1e MD |
360 | goto error; |
361 | } | |
5f003977 MD |
362 | if (sendret) { |
363 | ret = sendret; | |
364 | goto error; | |
365 | } | |
381c0f1e | 366 | } |
ef9ff354 MD |
367 | /* |
368 | * We still have the memory map reference, and the fds have been | |
3ad5f707 MD |
369 | * sent to the sessiond. We can therefore close those fds. Note |
370 | * that we keep the write side of the wait_fd open, but close | |
371 | * the read side. | |
ef9ff354 MD |
372 | */ |
373 | if (lur.ret_code == USTCOMM_OK) { | |
374 | switch (lum->cmd) { | |
375 | case LTTNG_UST_STREAM: | |
376 | if (shm_fd >= 0) { | |
377 | ret = close(shm_fd); | |
378 | if (ret) { | |
379 | PERROR("Error closing stream shm_fd"); | |
380 | } | |
381 | *args.stream.shm_fd = -1; | |
382 | } | |
383 | if (wait_fd >= 0) { | |
384 | ret = close(wait_fd); | |
385 | if (ret) { | |
386 | PERROR("Error closing stream wait_fd"); | |
387 | } | |
388 | *args.stream.wait_fd = -1; | |
389 | } | |
390 | break; | |
391 | case LTTNG_UST_METADATA: | |
392 | case LTTNG_UST_CHANNEL: | |
393 | if (shm_fd >= 0) { | |
394 | ret = close(shm_fd); | |
395 | if (ret) { | |
396 | PERROR("Error closing channel shm_fd"); | |
397 | } | |
398 | *args.channel.shm_fd = -1; | |
399 | } | |
400 | if (wait_fd >= 0) { | |
401 | ret = close(wait_fd); | |
402 | if (ret) { | |
403 | PERROR("Error closing channel wait_fd"); | |
404 | } | |
405 | *args.channel.wait_fd = -1; | |
406 | } | |
407 | break; | |
408 | } | |
409 | } | |
410 | ||
381c0f1e | 411 | error: |
17dfb34b | 412 | ust_unlock(); |
1ea11eab | 413 | return ret; |
d9e99d10 MD |
414 | } |
415 | ||
46050b1a | 416 | static |
efe0de09 | 417 | void cleanup_sock_info(struct sock_info *sock_info, int exiting) |
46050b1a MD |
418 | { |
419 | int ret; | |
420 | ||
421 | if (sock_info->socket != -1) { | |
e6973a89 | 422 | ret = ustcomm_close_unix_sock(sock_info->socket); |
46050b1a | 423 | if (ret) { |
7fc90dca | 424 | ERR("Error closing apps socket"); |
46050b1a MD |
425 | } |
426 | sock_info->socket = -1; | |
427 | } | |
428 | if (sock_info->root_handle != -1) { | |
d4419b81 | 429 | ret = lttng_ust_objd_unref(sock_info->root_handle); |
46050b1a MD |
430 | if (ret) { |
431 | ERR("Error unref root handle"); | |
432 | } | |
433 | sock_info->root_handle = -1; | |
434 | } | |
318dfea9 | 435 | sock_info->constructor_sem_posted = 0; |
efe0de09 MD |
436 | /* |
437 | * wait_shm_mmap is used by listener threads outside of the | |
438 | * ust lock, so we cannot tear it down ourselves, because we | |
439 | * cannot join on these threads. Leave this task to the OS | |
440 | * process exit. | |
441 | */ | |
442 | if (!exiting && sock_info->wait_shm_mmap) { | |
7fc90dca MD |
443 | ret = munmap(sock_info->wait_shm_mmap, sysconf(_SC_PAGE_SIZE)); |
444 | if (ret) { | |
445 | ERR("Error unmapping wait shm"); | |
446 | } | |
447 | sock_info->wait_shm_mmap = NULL; | |
448 | } | |
449 | } | |
450 | ||
58d4b2a2 | 451 | /* |
33bbeb90 MD |
452 | * Using fork to set umask in the child process (not multi-thread safe). |
453 | * We deal with the shm_open vs ftruncate race (happening when the | |
454 | * sessiond owns the shm and does not let everybody modify it, to ensure | |
455 | * safety against shm_unlink) by simply letting the mmap fail and | |
456 | * retrying after a few seconds. | |
457 | * For global shm, everybody has rw access to it until the sessiond | |
458 | * starts. | |
58d4b2a2 | 459 | */ |
7fc90dca | 460 | static |
58d4b2a2 | 461 | int get_wait_shm(struct sock_info *sock_info, size_t mmap_size) |
7fc90dca | 462 | { |
7fc90dca | 463 | int wait_shm_fd, ret; |
58d4b2a2 | 464 | pid_t pid; |
44e073f5 | 465 | |
58d4b2a2 | 466 | /* |
33bbeb90 | 467 | * Try to open read-only. |
58d4b2a2 | 468 | */ |
33bbeb90 | 469 | wait_shm_fd = shm_open(sock_info->wait_shm_path, O_RDONLY, 0); |
58d4b2a2 MD |
470 | if (wait_shm_fd >= 0) { |
471 | goto end; | |
472 | } else if (wait_shm_fd < 0 && errno != ENOENT) { | |
473 | /* | |
33bbeb90 MD |
474 | * Real-only open did not work, and it's not because the |
475 | * entry was not present. It's a failure that prohibits | |
476 | * using shm. | |
58d4b2a2 | 477 | */ |
7fc90dca | 478 | ERR("Error opening shm %s", sock_info->wait_shm_path); |
58d4b2a2 | 479 | goto end; |
7fc90dca MD |
480 | } |
481 | /* | |
58d4b2a2 MD |
482 | * If the open failed because the file did not exist, try |
483 | * creating it ourself. | |
7fc90dca | 484 | */ |
3b8b68e7 | 485 | lttng_ust_nest_count++; |
58d4b2a2 | 486 | pid = fork(); |
3b8b68e7 | 487 | lttng_ust_nest_count--; |
58d4b2a2 MD |
488 | if (pid > 0) { |
489 | int status; | |
490 | ||
491 | /* | |
492 | * Parent: wait for child to return, in which case the | |
493 | * shared memory map will have been created. | |
494 | */ | |
495 | pid = wait(&status); | |
b7d3cb32 | 496 | if (pid < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) { |
58d4b2a2 MD |
497 | wait_shm_fd = -1; |
498 | goto end; | |
7fc90dca | 499 | } |
58d4b2a2 MD |
500 | /* |
501 | * Try to open read-only again after creation. | |
502 | */ | |
33bbeb90 | 503 | wait_shm_fd = shm_open(sock_info->wait_shm_path, O_RDONLY, 0); |
58d4b2a2 MD |
504 | if (wait_shm_fd < 0) { |
505 | /* | |
506 | * Real-only open did not work. It's a failure | |
507 | * that prohibits using shm. | |
508 | */ | |
509 | ERR("Error opening shm %s", sock_info->wait_shm_path); | |
510 | goto end; | |
511 | } | |
512 | goto end; | |
513 | } else if (pid == 0) { | |
514 | int create_mode; | |
515 | ||
516 | /* Child */ | |
33bbeb90 | 517 | create_mode = S_IRUSR | S_IWUSR | S_IRGRP; |
58d4b2a2 | 518 | if (sock_info->global) |
33bbeb90 | 519 | create_mode |= S_IROTH | S_IWGRP | S_IWOTH; |
58d4b2a2 MD |
520 | /* |
521 | * We're alone in a child process, so we can modify the | |
522 | * process-wide umask. | |
523 | */ | |
33bbeb90 | 524 | umask(~create_mode); |
58d4b2a2 | 525 | /* |
33bbeb90 MD |
526 | * Try creating shm (or get rw access). |
527 | * We don't do an exclusive open, because we allow other | |
528 | * processes to create+ftruncate it concurrently. | |
58d4b2a2 MD |
529 | */ |
530 | wait_shm_fd = shm_open(sock_info->wait_shm_path, | |
531 | O_RDWR | O_CREAT, create_mode); | |
532 | if (wait_shm_fd >= 0) { | |
533 | ret = ftruncate(wait_shm_fd, mmap_size); | |
534 | if (ret) { | |
535 | PERROR("ftruncate"); | |
c0872615 | 536 | _exit(EXIT_FAILURE); |
58d4b2a2 | 537 | } |
c0872615 | 538 | _exit(EXIT_SUCCESS); |
58d4b2a2 | 539 | } |
33bbeb90 MD |
540 | /* |
541 | * For local shm, we need to have rw access to accept | |
542 | * opening it: this means the local sessiond will be | |
543 | * able to wake us up. For global shm, we open it even | |
544 | * if rw access is not granted, because the root.root | |
545 | * sessiond will be able to override all rights and wake | |
546 | * us up. | |
547 | */ | |
548 | if (!sock_info->global && errno != EACCES) { | |
58d4b2a2 | 549 | ERR("Error opening shm %s", sock_info->wait_shm_path); |
63375cce | 550 | _exit(EXIT_FAILURE); |
58d4b2a2 MD |
551 | } |
552 | /* | |
33bbeb90 MD |
553 | * The shm exists, but we cannot open it RW. Report |
554 | * success. | |
58d4b2a2 | 555 | */ |
63375cce | 556 | _exit(EXIT_SUCCESS); |
58d4b2a2 MD |
557 | } else { |
558 | return -1; | |
7fc90dca | 559 | } |
58d4b2a2 | 560 | end: |
33bbeb90 MD |
561 | if (wait_shm_fd >= 0 && !sock_info->global) { |
562 | struct stat statbuf; | |
563 | ||
564 | /* | |
565 | * Ensure that our user is the owner of the shm file for | |
566 | * local shm. If we do not own the file, it means our | |
567 | * sessiond will not have access to wake us up (there is | |
568 | * probably a rogue process trying to fake our | |
569 | * sessiond). Fallback to polling method in this case. | |
570 | */ | |
571 | ret = fstat(wait_shm_fd, &statbuf); | |
572 | if (ret) { | |
573 | PERROR("fstat"); | |
574 | goto error_close; | |
575 | } | |
576 | if (statbuf.st_uid != getuid()) | |
577 | goto error_close; | |
578 | } | |
58d4b2a2 | 579 | return wait_shm_fd; |
33bbeb90 MD |
580 | |
581 | error_close: | |
582 | ret = close(wait_shm_fd); | |
583 | if (ret) { | |
584 | PERROR("Error closing fd"); | |
585 | } | |
586 | return -1; | |
58d4b2a2 MD |
587 | } |
588 | ||
589 | static | |
590 | char *get_map_shm(struct sock_info *sock_info) | |
591 | { | |
592 | size_t mmap_size = sysconf(_SC_PAGE_SIZE); | |
593 | int wait_shm_fd, ret; | |
594 | char *wait_shm_mmap; | |
595 | ||
596 | wait_shm_fd = get_wait_shm(sock_info, mmap_size); | |
597 | if (wait_shm_fd < 0) { | |
598 | goto error; | |
44e073f5 | 599 | } |
7fc90dca MD |
600 | wait_shm_mmap = mmap(NULL, mmap_size, PROT_READ, |
601 | MAP_SHARED, wait_shm_fd, 0); | |
7fc90dca MD |
602 | /* close shm fd immediately after taking the mmap reference */ |
603 | ret = close(wait_shm_fd); | |
604 | if (ret) { | |
33bbeb90 MD |
605 | PERROR("Error closing fd"); |
606 | } | |
607 | if (wait_shm_mmap == MAP_FAILED) { | |
608 | DBG("mmap error (can be caused by race with sessiond). Fallback to poll mode."); | |
609 | goto error; | |
7fc90dca MD |
610 | } |
611 | return wait_shm_mmap; | |
612 | ||
613 | error: | |
614 | return NULL; | |
615 | } | |
616 | ||
617 | static | |
618 | void wait_for_sessiond(struct sock_info *sock_info) | |
619 | { | |
efe0de09 | 620 | int ret; |
80e2814b | 621 | |
7fc90dca MD |
622 | ust_lock(); |
623 | if (lttng_ust_comm_should_quit) { | |
624 | goto quit; | |
625 | } | |
37ed587a MD |
626 | if (wait_poll_fallback) { |
627 | goto error; | |
628 | } | |
7fc90dca MD |
629 | if (!sock_info->wait_shm_mmap) { |
630 | sock_info->wait_shm_mmap = get_map_shm(sock_info); | |
631 | if (!sock_info->wait_shm_mmap) | |
632 | goto error; | |
633 | } | |
634 | ust_unlock(); | |
635 | ||
636 | DBG("Waiting for %s apps sessiond", sock_info->name); | |
80e2814b MD |
637 | /* Wait for futex wakeup */ |
638 | if (uatomic_read((int32_t *) sock_info->wait_shm_mmap) == 0) { | |
639 | ret = futex_async((int32_t *) sock_info->wait_shm_mmap, | |
640 | FUTEX_WAIT, 0, NULL, NULL, 0); | |
80e2814b | 641 | if (ret < 0) { |
37ed587a MD |
642 | if (errno == EFAULT) { |
643 | wait_poll_fallback = 1; | |
a8b870ad | 644 | DBG( |
37ed587a MD |
645 | "Linux kernels 2.6.33 to 3.0 (with the exception of stable versions) " |
646 | "do not support FUTEX_WAKE on read-only memory mappings correctly. " | |
647 | "Please upgrade your kernel " | |
648 | "(fix is commit 9ea71503a8ed9184d2d0b8ccc4d269d05f7940ae in Linux kernel " | |
649 | "mainline). LTTng-UST will use polling mode fallback."); | |
cd27263b MD |
650 | if (ust_debug()) |
651 | PERROR("futex"); | |
37ed587a | 652 | } |
80e2814b MD |
653 | } |
654 | } | |
7fc90dca MD |
655 | return; |
656 | ||
657 | quit: | |
658 | ust_unlock(); | |
659 | return; | |
660 | ||
661 | error: | |
662 | ust_unlock(); | |
7fc90dca | 663 | return; |
46050b1a MD |
664 | } |
665 | ||
1ea11eab MD |
666 | /* |
667 | * This thread does not allocate any resource, except within | |
668 | * handle_message, within mutex protection. This mutex protects against | |
669 | * fork and exit. | |
670 | * The other moment it allocates resources is at socket connexion, which | |
671 | * is also protected by the mutex. | |
672 | */ | |
d9e99d10 MD |
673 | static |
674 | void *ust_listener_thread(void *arg) | |
675 | { | |
1ea11eab | 676 | struct sock_info *sock_info = arg; |
c0eedf81 | 677 | int sock, ret, prev_connect_failed = 0, has_waited = 0; |
d9e99d10 | 678 | |
9eb62b9c MD |
679 | /* Restart trying to connect to the session daemon */ |
680 | restart: | |
c0eedf81 MD |
681 | if (prev_connect_failed) { |
682 | /* Wait for sessiond availability with pipe */ | |
683 | wait_for_sessiond(sock_info); | |
684 | if (has_waited) { | |
685 | has_waited = 0; | |
686 | /* | |
687 | * Sleep for 5 seconds before retrying after a | |
688 | * sequence of failure / wait / failure. This | |
689 | * deals with a killed or broken session daemon. | |
690 | */ | |
691 | sleep(5); | |
692 | } | |
693 | has_waited = 1; | |
694 | prev_connect_failed = 0; | |
695 | } | |
17dfb34b | 696 | ust_lock(); |
1ea11eab MD |
697 | |
698 | if (lttng_ust_comm_should_quit) { | |
17dfb34b | 699 | ust_unlock(); |
1ea11eab MD |
700 | goto quit; |
701 | } | |
9eb62b9c | 702 | |
1ea11eab | 703 | if (sock_info->socket != -1) { |
e6973a89 | 704 | ret = ustcomm_close_unix_sock(sock_info->socket); |
1ea11eab | 705 | if (ret) { |
11ff9c7d | 706 | ERR("Error closing %s apps socket", sock_info->name); |
1ea11eab MD |
707 | } |
708 | sock_info->socket = -1; | |
709 | } | |
46050b1a | 710 | |
9eb62b9c | 711 | /* Register */ |
57773204 | 712 | ret = ustcomm_connect_unix_sock(sock_info->sock_path); |
9eb62b9c | 713 | if (ret < 0) { |
4d3c9523 | 714 | DBG("Info: sessiond not accepting connections to %s apps socket", sock_info->name); |
c0eedf81 | 715 | prev_connect_failed = 1; |
11ff9c7d MD |
716 | /* |
717 | * If we cannot find the sessiond daemon, don't delay | |
718 | * constructor execution. | |
719 | */ | |
edaa1431 | 720 | ret = handle_register_done(sock_info); |
11ff9c7d | 721 | assert(!ret); |
17dfb34b | 722 | ust_unlock(); |
1ea11eab | 723 | goto restart; |
46050b1a MD |
724 | } |
725 | ||
726 | sock_info->socket = sock = ret; | |
727 | ||
728 | /* | |
729 | * Create only one root handle per listener thread for the whole | |
730 | * process lifetime. | |
731 | */ | |
732 | if (sock_info->root_handle == -1) { | |
733 | ret = lttng_abi_create_root_handle(); | |
a51070bb | 734 | if (ret < 0) { |
46050b1a | 735 | ERR("Error creating root handle"); |
17dfb34b | 736 | ust_unlock(); |
46050b1a MD |
737 | goto quit; |
738 | } | |
739 | sock_info->root_handle = ret; | |
9eb62b9c | 740 | } |
1ea11eab | 741 | |
9eb62b9c MD |
742 | ret = register_app_to_sessiond(sock); |
743 | if (ret < 0) { | |
11ff9c7d | 744 | ERR("Error registering to %s apps socket", sock_info->name); |
c0eedf81 | 745 | prev_connect_failed = 1; |
11ff9c7d MD |
746 | /* |
747 | * If we cannot register to the sessiond daemon, don't | |
748 | * delay constructor execution. | |
749 | */ | |
edaa1431 | 750 | ret = handle_register_done(sock_info); |
11ff9c7d | 751 | assert(!ret); |
17dfb34b | 752 | ust_unlock(); |
9eb62b9c MD |
753 | goto restart; |
754 | } | |
17dfb34b | 755 | ust_unlock(); |
46050b1a | 756 | |
d9e99d10 MD |
757 | for (;;) { |
758 | ssize_t len; | |
57773204 | 759 | struct ustcomm_ust_msg lum; |
d9e99d10 | 760 | |
57773204 | 761 | len = ustcomm_recv_unix_sock(sock, &lum, sizeof(lum)); |
d9e99d10 MD |
762 | switch (len) { |
763 | case 0: /* orderly shutdown */ | |
11ff9c7d | 764 | DBG("%s ltt-sessiond has performed an orderly shutdown\n", sock_info->name); |
8236ba10 MD |
765 | ust_lock(); |
766 | /* | |
767 | * Either sessiond has shutdown or refused us by closing the socket. | |
768 | * In either case, we don't want to delay construction execution, | |
769 | * and we need to wait before retry. | |
770 | */ | |
771 | prev_connect_failed = 1; | |
772 | /* | |
773 | * If we cannot register to the sessiond daemon, don't | |
774 | * delay constructor execution. | |
775 | */ | |
776 | ret = handle_register_done(sock_info); | |
777 | assert(!ret); | |
778 | ust_unlock(); | |
d9e99d10 | 779 | goto end; |
e7723462 | 780 | case sizeof(lum): |
d9e99d10 | 781 | DBG("message received\n"); |
11ff9c7d | 782 | ret = handle_message(sock_info, sock, &lum); |
2a80c9d8 | 783 | if (ret < 0) { |
11ff9c7d | 784 | ERR("Error handling message for %s socket", sock_info->name); |
d9e99d10 MD |
785 | } |
786 | continue; | |
787 | case -1: | |
8236ba10 | 788 | DBG("Receive failed from lttng-sessiond with errno %d", errno); |
d9e99d10 | 789 | if (errno == ECONNRESET) { |
11ff9c7d | 790 | ERR("%s remote end closed connection\n", sock_info->name); |
d9e99d10 MD |
791 | goto end; |
792 | } | |
793 | goto end; | |
794 | default: | |
11ff9c7d | 795 | ERR("incorrect message size (%s socket): %zd\n", sock_info->name, len); |
d9e99d10 MD |
796 | continue; |
797 | } | |
798 | ||
799 | } | |
800 | end: | |
9eb62b9c | 801 | goto restart; /* try to reconnect */ |
1ea11eab | 802 | quit: |
d9e99d10 MD |
803 | return NULL; |
804 | } | |
805 | ||
cf12a773 MD |
806 | /* |
807 | * Return values: -1: don't wait. 0: wait forever. 1: timeout wait. | |
808 | */ | |
11ff9c7d MD |
809 | static |
810 | int get_timeout(struct timespec *constructor_timeout) | |
811 | { | |
cf12a773 MD |
812 | long constructor_delay_ms = LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS; |
813 | char *str_delay; | |
11ff9c7d MD |
814 | int ret; |
815 | ||
69400ac4 | 816 | str_delay = getenv("LTTNG_UST_REGISTER_TIMEOUT"); |
cf12a773 MD |
817 | if (str_delay) { |
818 | constructor_delay_ms = strtol(str_delay, NULL, 10); | |
819 | } | |
820 | ||
821 | switch (constructor_delay_ms) { | |
822 | case -1:/* fall-through */ | |
823 | case 0: | |
824 | return constructor_delay_ms; | |
825 | default: | |
826 | break; | |
827 | } | |
828 | ||
829 | /* | |
830 | * If we are unable to find the current time, don't wait. | |
831 | */ | |
832 | ret = clock_gettime(CLOCK_REALTIME, constructor_timeout); | |
833 | if (ret) { | |
834 | return -1; | |
835 | } | |
95259bd0 MD |
836 | constructor_timeout->tv_sec += constructor_delay_ms / 1000UL; |
837 | constructor_timeout->tv_nsec += | |
838 | (constructor_delay_ms % 1000UL) * 1000000UL; | |
11ff9c7d MD |
839 | if (constructor_timeout->tv_nsec >= 1000000000UL) { |
840 | constructor_timeout->tv_sec++; | |
841 | constructor_timeout->tv_nsec -= 1000000000UL; | |
842 | } | |
cf12a773 | 843 | return 1; |
11ff9c7d | 844 | } |
d9e99d10 | 845 | |
2691221a MD |
846 | /* |
847 | * sessiond monitoring thread: monitor presence of global and per-user | |
848 | * sessiond by polling the application common named pipe. | |
849 | */ | |
850 | /* TODO */ | |
851 | ||
edaa1431 | 852 | void __attribute__((constructor)) lttng_ust_init(void) |
2691221a | 853 | { |
11ff9c7d | 854 | struct timespec constructor_timeout; |
e32d20e9 | 855 | sigset_t sig_all_blocked, orig_parent_mask; |
e63683c7 | 856 | pthread_attr_t thread_attr; |
cf12a773 | 857 | int timeout_mode; |
2691221a MD |
858 | int ret; |
859 | ||
edaa1431 MD |
860 | if (uatomic_xchg(&initialized, 1) == 1) |
861 | return; | |
862 | ||
eddd8d5d MD |
863 | /* |
864 | * Fixup interdependency between TLS fixup mutex (which happens | |
865 | * to be the dynamic linker mutex) and ust_lock, taken within | |
866 | * the ust lock. | |
867 | */ | |
868 | lttng_fixup_event_tls(); | |
f645cfa7 | 869 | lttng_fixup_ringbuffer_tls(); |
4158a15a | 870 | lttng_fixup_vtid_tls(); |
e38c8fc1 | 871 | lttng_fixup_nest_count_tls(); |
eddd8d5d | 872 | |
edaa1431 MD |
873 | /* |
874 | * We want precise control over the order in which we construct | |
875 | * our sub-libraries vs starting to receive commands from | |
876 | * sessiond (otherwise leading to errors when trying to create | |
877 | * sessiond before the init functions are completed). | |
878 | */ | |
2691221a | 879 | init_usterr(); |
edaa1431 MD |
880 | init_tracepoint(); |
881 | ltt_ring_buffer_metadata_client_init(); | |
882 | ltt_ring_buffer_client_overwrite_init(); | |
883 | ltt_ring_buffer_client_discard_init(); | |
2691221a | 884 | |
cf12a773 | 885 | timeout_mode = get_timeout(&constructor_timeout); |
11ff9c7d | 886 | |
95259bd0 | 887 | ret = sem_init(&constructor_wait, 0, 0); |
11ff9c7d MD |
888 | assert(!ret); |
889 | ||
8d20bf54 | 890 | ret = setup_local_apps(); |
2691221a | 891 | if (ret) { |
e699eda9 | 892 | DBG("local apps setup returned %d", ret); |
2691221a | 893 | } |
e32d20e9 WP |
894 | |
895 | /* A new thread created by pthread_create inherits the signal mask | |
896 | * from the parent. To avoid any signal being received by the | |
897 | * listener thread, we block all signals temporarily in the parent, | |
898 | * while we create the listener thread. | |
899 | */ | |
900 | sigfillset(&sig_all_blocked); | |
901 | ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_parent_mask); | |
902 | if (ret) { | |
e37047b6 | 903 | ERR("pthread_sigmask: %s", strerror(ret)); |
e32d20e9 WP |
904 | } |
905 | ||
e63683c7 MG |
906 | ret = pthread_attr_init(&thread_attr); |
907 | if (ret) { | |
908 | ERR("pthread_attr_init: %s", strerror(ret)); | |
909 | } | |
910 | ret = pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_DETACHED); | |
911 | if (ret) { | |
912 | ERR("pthread_attr_setdetachstate: %s", strerror(ret)); | |
913 | } | |
914 | ||
915 | ret = pthread_create(&global_apps.ust_listener, &thread_attr, | |
dc43c97f | 916 | ust_listener_thread, &global_apps); |
e37047b6 MD |
917 | if (ret) { |
918 | ERR("pthread_create global: %s", strerror(ret)); | |
919 | } | |
8d20bf54 | 920 | if (local_apps.allowed) { |
e63683c7 | 921 | ret = pthread_create(&local_apps.ust_listener, &thread_attr, |
dc43c97f | 922 | ust_listener_thread, &local_apps); |
e37047b6 MD |
923 | if (ret) { |
924 | ERR("pthread_create local: %s", strerror(ret)); | |
925 | } | |
8d20bf54 MD |
926 | } else { |
927 | handle_register_done(&local_apps); | |
928 | } | |
e63683c7 MG |
929 | ret = pthread_attr_destroy(&thread_attr); |
930 | if (ret) { | |
931 | ERR("pthread_attr_destroy: %s", strerror(ret)); | |
932 | } | |
8d20bf54 | 933 | |
e32d20e9 WP |
934 | /* Restore original signal mask in parent */ |
935 | ret = pthread_sigmask(SIG_SETMASK, &orig_parent_mask, NULL); | |
936 | if (ret) { | |
e37047b6 | 937 | ERR("pthread_sigmask: %s", strerror(ret)); |
e32d20e9 WP |
938 | } |
939 | ||
cf12a773 MD |
940 | switch (timeout_mode) { |
941 | case 1: /* timeout wait */ | |
95259bd0 MD |
942 | do { |
943 | ret = sem_timedwait(&constructor_wait, | |
944 | &constructor_timeout); | |
945 | } while (ret < 0 && errno == EINTR); | |
cf12a773 MD |
946 | if (ret < 0 && errno == ETIMEDOUT) { |
947 | ERR("Timed out waiting for ltt-sessiond"); | |
948 | } else { | |
949 | assert(!ret); | |
950 | } | |
951 | break; | |
7b766b16 | 952 | case -1:/* wait forever */ |
95259bd0 MD |
953 | do { |
954 | ret = sem_wait(&constructor_wait); | |
955 | } while (ret < 0 && errno == EINTR); | |
11ff9c7d | 956 | assert(!ret); |
cf12a773 | 957 | break; |
7b766b16 | 958 | case 0: /* no timeout */ |
cf12a773 | 959 | break; |
11ff9c7d | 960 | } |
2691221a MD |
961 | } |
962 | ||
17dfb34b MD |
963 | static |
964 | void lttng_ust_cleanup(int exiting) | |
965 | { | |
efe0de09 | 966 | cleanup_sock_info(&global_apps, exiting); |
17dfb34b | 967 | if (local_apps.allowed) { |
efe0de09 | 968 | cleanup_sock_info(&local_apps, exiting); |
17dfb34b | 969 | } |
efe0de09 MD |
970 | /* |
971 | * The teardown in this function all affect data structures | |
972 | * accessed under the UST lock by the listener thread. This | |
973 | * lock, along with the lttng_ust_comm_should_quit flag, ensure | |
974 | * that none of these threads are accessing this data at this | |
975 | * point. | |
976 | */ | |
17dfb34b | 977 | lttng_ust_abi_exit(); |
003fedf4 | 978 | lttng_ust_events_exit(); |
17dfb34b MD |
979 | ltt_ring_buffer_client_discard_exit(); |
980 | ltt_ring_buffer_client_overwrite_exit(); | |
981 | ltt_ring_buffer_metadata_client_exit(); | |
982 | exit_tracepoint(); | |
983 | if (!exiting) { | |
984 | /* Reinitialize values for fork */ | |
985 | sem_count = 2; | |
986 | lttng_ust_comm_should_quit = 0; | |
987 | initialized = 0; | |
988 | } | |
989 | } | |
990 | ||
edaa1431 | 991 | void __attribute__((destructor)) lttng_ust_exit(void) |
2691221a MD |
992 | { |
993 | int ret; | |
994 | ||
9eb62b9c MD |
995 | /* |
996 | * Using pthread_cancel here because: | |
997 | * A) we don't want to hang application teardown. | |
998 | * B) the thread is not allocating any resource. | |
999 | */ | |
1ea11eab MD |
1000 | |
1001 | /* | |
1002 | * Require the communication thread to quit. Synchronize with | |
1003 | * mutexes to ensure it is not in a mutex critical section when | |
1004 | * pthread_cancel is later called. | |
1005 | */ | |
17dfb34b | 1006 | ust_lock(); |
1ea11eab | 1007 | lttng_ust_comm_should_quit = 1; |
17dfb34b | 1008 | ust_unlock(); |
1ea11eab | 1009 | |
f5f94532 | 1010 | /* cancel threads */ |
1ea11eab | 1011 | ret = pthread_cancel(global_apps.ust_listener); |
9eb62b9c | 1012 | if (ret) { |
e37047b6 MD |
1013 | ERR("Error cancelling global ust listener thread: %s", |
1014 | strerror(ret)); | |
2691221a | 1015 | } |
8d20bf54 MD |
1016 | if (local_apps.allowed) { |
1017 | ret = pthread_cancel(local_apps.ust_listener); | |
1018 | if (ret) { | |
e37047b6 MD |
1019 | ERR("Error cancelling local ust listener thread: %s", |
1020 | strerror(ret)); | |
8d20bf54 | 1021 | } |
8d20bf54 | 1022 | } |
efe0de09 MD |
1023 | /* |
1024 | * Do NOT join threads: use of sys_futex makes it impossible to | |
1025 | * join the threads without using async-cancel, but async-cancel | |
1026 | * is delivered by a signal, which could hit the target thread | |
1027 | * anywhere in its code path, including while the ust_lock() is | |
1028 | * held, causing a deadlock for the other thread. Let the OS | |
1029 | * cleanup the threads if there are stalled in a syscall. | |
1030 | */ | |
17dfb34b | 1031 | lttng_ust_cleanup(1); |
2691221a | 1032 | } |
e822f505 MD |
1033 | |
1034 | /* | |
1035 | * We exclude the worker threads across fork and clone (except | |
1036 | * CLONE_VM), because these system calls only keep the forking thread | |
1037 | * running in the child. Therefore, we don't want to call fork or clone | |
1038 | * in the middle of an tracepoint or ust tracing state modification. | |
1039 | * Holding this mutex protects these structures across fork and clone. | |
1040 | */ | |
b728d87e | 1041 | void ust_before_fork(sigset_t *save_sigset) |
e822f505 MD |
1042 | { |
1043 | /* | |
1044 | * Disable signals. This is to avoid that the child intervenes | |
1045 | * before it is properly setup for tracing. It is safer to | |
1046 | * disable all signals, because then we know we are not breaking | |
1047 | * anything by restoring the original mask. | |
1048 | */ | |
1049 | sigset_t all_sigs; | |
1050 | int ret; | |
1051 | ||
3b8b68e7 MD |
1052 | if (lttng_ust_nest_count) |
1053 | return; | |
e822f505 MD |
1054 | /* Disable signals */ |
1055 | sigfillset(&all_sigs); | |
b728d87e | 1056 | ret = sigprocmask(SIG_BLOCK, &all_sigs, save_sigset); |
e822f505 MD |
1057 | if (ret == -1) { |
1058 | PERROR("sigprocmask"); | |
1059 | } | |
17dfb34b | 1060 | ust_lock(); |
e822f505 MD |
1061 | rcu_bp_before_fork(); |
1062 | } | |
1063 | ||
b728d87e | 1064 | static void ust_after_fork_common(sigset_t *restore_sigset) |
e822f505 MD |
1065 | { |
1066 | int ret; | |
1067 | ||
17dfb34b MD |
1068 | DBG("process %d", getpid()); |
1069 | ust_unlock(); | |
e822f505 | 1070 | /* Restore signals */ |
23c8854a | 1071 | ret = sigprocmask(SIG_SETMASK, restore_sigset, NULL); |
e822f505 MD |
1072 | if (ret == -1) { |
1073 | PERROR("sigprocmask"); | |
1074 | } | |
1075 | } | |
1076 | ||
b728d87e | 1077 | void ust_after_fork_parent(sigset_t *restore_sigset) |
e822f505 | 1078 | { |
3b8b68e7 MD |
1079 | if (lttng_ust_nest_count) |
1080 | return; | |
17dfb34b | 1081 | DBG("process %d", getpid()); |
e822f505 MD |
1082 | rcu_bp_after_fork_parent(); |
1083 | /* Release mutexes and reenable signals */ | |
b728d87e | 1084 | ust_after_fork_common(restore_sigset); |
e822f505 MD |
1085 | } |
1086 | ||
17dfb34b MD |
1087 | /* |
1088 | * After fork, in the child, we need to cleanup all the leftover state, | |
1089 | * except the worker thread which already magically disappeared thanks | |
1090 | * to the weird Linux fork semantics. After tyding up, we call | |
1091 | * lttng_ust_init() again to start over as a new PID. | |
1092 | * | |
1093 | * This is meant for forks() that have tracing in the child between the | |
1094 | * fork and following exec call (if there is any). | |
1095 | */ | |
b728d87e | 1096 | void ust_after_fork_child(sigset_t *restore_sigset) |
e822f505 | 1097 | { |
3b8b68e7 MD |
1098 | if (lttng_ust_nest_count) |
1099 | return; | |
17dfb34b | 1100 | DBG("process %d", getpid()); |
e822f505 MD |
1101 | /* Release urcu mutexes */ |
1102 | rcu_bp_after_fork_child(); | |
17dfb34b | 1103 | lttng_ust_cleanup(0); |
a93bfc45 | 1104 | lttng_context_vtid_reset(); |
e822f505 | 1105 | /* Release mutexes and reenable signals */ |
b728d87e | 1106 | ust_after_fork_common(restore_sigset); |
318dfea9 | 1107 | lttng_ust_init(); |
e822f505 | 1108 | } |