1 | /* Copyright (C) 2002-2017 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. |
3 | Contributed by Ulrich Drepper <drepper@redhat.com>, 2002. |
4 | |
5 | The GNU C Library is free software; you can redistribute it and/or |
6 | modify it under the terms of the GNU Lesser General Public |
7 | License as published by the Free Software Foundation; either |
8 | version 2.1 of the License, or (at your option) any later version. |
9 | |
10 | The GNU C Library is distributed in the hope that it will be useful, |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
13 | Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public |
16 | License along with the GNU C Library; if not, see |
17 | <http://www.gnu.org/licenses/>. */ |
18 | |
19 | #include <ctype.h> |
20 | #include <errno.h> |
21 | #include <stdbool.h> |
22 | #include <stdlib.h> |
23 | #include <string.h> |
24 | #include <stdint.h> |
25 | #include "pthreadP.h" |
26 | #include <hp-timing.h> |
27 | #include <ldsodefs.h> |
28 | #include <atomic.h> |
29 | #include <libc-internal.h> |
30 | #include <resolv.h> |
31 | #include <kernel-features.h> |
32 | #include <exit-thread.h> |
33 | #include <default-sched.h> |
34 | #include <futex-internal.h> |
35 | #include "libioP.h" |
36 | |
37 | #include <shlib-compat.h> |
38 | |
39 | #include <stap-probe.h> |
40 | |
41 | |
42 | /* Nozero if debugging mode is enabled. */ |
43 | int __pthread_debug; |
44 | |
45 | /* Globally enabled events. */ |
46 | static td_thr_events_t __nptl_threads_events __attribute_used__; |
47 | |
48 | /* Pointer to descriptor with the last event. */ |
49 | static struct pthread *__nptl_last_event __attribute_used__; |
50 | |
51 | /* Number of threads running. */ |
52 | unsigned int __nptl_nthreads = 1; |
53 | |
54 | |
55 | /* Code to allocate and deallocate a stack. */ |
56 | #include "allocatestack.c" |
57 | |
58 | /* CONCURRENCY NOTES: |
59 | |
60 | Understanding who is the owner of the 'struct pthread' or 'PD' |
61 | (refers to the value of the 'struct pthread *pd' function argument) |
62 | is critically important in determining exactly which operations are |
63 | allowed and which are not and when, particularly when it comes to the |
64 | implementation of pthread_create, pthread_join, pthread_detach, and |
65 | other functions which all operate on PD. |
66 | |
67 | The owner of PD is responsible for freeing the final resources |
68 | associated with PD, and may examine the memory underlying PD at any |
69 | point in time until it frees it back to the OS or to reuse by the |
70 | runtime. |
71 | |
72 | The thread which calls pthread_create is called the creating thread. |
73 | The creating thread begins as the owner of PD. |
74 | |
75 | During startup the new thread may examine PD in coordination with the |
76 | owner thread (which may be itself). |
77 | |
78 | The four cases of ownership transfer are: |
79 | |
80 | (1) Ownership of PD is released to the process (all threads may use it) |
81 | after the new thread starts in a joinable state |
82 | i.e. pthread_create returns a usable pthread_t. |
83 | |
84 | (2) Ownership of PD is released to the new thread starting in a detached |
85 | state. |
86 | |
87 | (3) Ownership of PD is dynamically released to a running thread via |
88 | pthread_detach. |
89 | |
90 | (4) Ownership of PD is acquired by the thread which calls pthread_join. |
91 | |
92 | Implementation notes: |
93 | |
94 | The PD->stopped_start and thread_ran variables are used to determine |
95 | exactly which of the four ownership states we are in and therefore |
96 | what actions can be taken. For example after (2) we cannot read or |
97 | write from PD anymore since the thread may no longer exist and the |
98 | memory may be unmapped. |
99 | |
100 | It is important to point out that PD->lock is being used both |
101 | similar to a one-shot semaphore and subsequently as a mutex. The |
102 | lock is taken in the parent to force the child to wait, and then the |
103 | child releases the lock. However, this semaphore-like effect is used |
104 | only for synchronizing the parent and child. After startup the lock |
105 | is used like a mutex to create a critical section during which a |
106 | single owner modifies the thread parameters. |
107 | |
108 | The most complicated cases happen during thread startup: |
109 | |
110 | (a) If the created thread is in a detached (PTHREAD_CREATE_DETACHED), |
111 | or joinable (default PTHREAD_CREATE_JOINABLE) state and |
112 | STOPPED_START is true, then the creating thread has ownership of |
113 | PD until the PD->lock is released by pthread_create. If any |
114 | errors occur we are in states (c), (d), or (e) below. |
115 | |
116 | (b) If the created thread is in a detached state |
117 | (PTHREAD_CREATED_DETACHED), and STOPPED_START is false, then the |
118 | creating thread has ownership of PD until it invokes the OS |
119 | kernel's thread creation routine. If this routine returns |
120 | without error, then the created thread owns PD; otherwise, see |
121 | (c) and (e) below. |
122 | |
123 | (c) If the detached thread setup failed and THREAD_RAN is true, then |
124 | the creating thread releases ownership to the new thread by |
125 | sending a cancellation signal. All threads set THREAD_RAN to |
126 | true as quickly as possible after returning from the OS kernel's |
127 | thread creation routine. |
128 | |
129 | (d) If the joinable thread setup failed and THREAD_RAN is true, then |
130 | then the creating thread retains ownership of PD and must cleanup |
131 | state. Ownership cannot be released to the process via the |
132 | return of pthread_create since a non-zero result entails PD is |
133 | undefined and therefore cannot be joined to free the resources. |
134 | We privately call pthread_join on the thread to finish handling |
135 | the resource shutdown (Or at least we should, see bug 19511). |
136 | |
137 | (e) If the thread creation failed and THREAD_RAN is false, then the |
138 | creating thread retains ownership of PD and must cleanup state. |
139 | No waiting for the new thread is required because it never |
140 | started. |
141 | |
142 | The nptl_db interface: |
143 | |
144 | The interface with nptl_db requires that we enqueue PD into a linked |
145 | list and then call a function which the debugger will trap. The PD |
146 | will then be dequeued and control returned to the thread. The caller |
147 | at the time must have ownership of PD and such ownership remains |
148 | after control returns to thread. The enqueued PD is removed from the |
149 | linked list by the nptl_db callback td_thr_event_getmsg. The debugger |
150 | must ensure that the thread does not resume execution, otherwise |
151 | ownership of PD may be lost and examining PD will not be possible. |
152 | |
153 | Note that the GNU Debugger as of (December 10th 2015) commit |
154 | c2c2a31fdb228d41ce3db62b268efea04bd39c18 no longer uses |
155 | td_thr_event_getmsg and several other related nptl_db interfaces. The |
156 | principal reason for this is that nptl_db does not support non-stop |
157 | mode where other threads can run concurrently and modify runtime |
158 | structures currently in use by the debugger and the nptl_db |
159 | interface. |
160 | |
161 | Axioms: |
162 | |
163 | * The create_thread function can never set stopped_start to false. |
164 | * The created thread can read stopped_start but never write to it. |
165 | * The variable thread_ran is set some time after the OS thread |
166 | creation routine returns, how much time after the thread is created |
167 | is unspecified, but it should be as quickly as possible. |
168 | |
169 | */ |
170 | |
171 | /* CREATE THREAD NOTES: |
172 | |
173 | createthread.c defines the create_thread function, and two macros: |
174 | START_THREAD_DEFN and START_THREAD_SELF (see below). |
175 | |
176 | create_thread must initialize PD->stopped_start. It should be true |
177 | if the STOPPED_START parameter is true, or if create_thread needs the |
178 | new thread to synchronize at startup for some other implementation |
179 | reason. If STOPPED_START will be true, then create_thread is obliged |
180 | to lock PD->lock before starting the thread. Then pthread_create |
181 | unlocks PD->lock which synchronizes-with START_THREAD_DEFN in the |
182 | child thread which does an acquire/release of PD->lock as the last |
183 | action before calling the user entry point. The goal of all of this |
184 | is to ensure that the required initial thread attributes are applied |
185 | (by the creating thread) before the new thread runs user code. Note |
186 | that the the functions pthread_getschedparam, pthread_setschedparam, |
187 | pthread_setschedprio, __pthread_tpp_change_priority, and |
188 | __pthread_current_priority reuse the same lock, PD->lock, for a |
189 | similar purpose e.g. synchronizing the setting of similar thread |
190 | attributes. These functions are never called before the thread is |
191 | created, so don't participate in startup syncronization, but given |
192 | that the lock is present already and in the unlocked state, reusing |
193 | it saves space. |
194 | |
195 | The return value is zero for success or an errno code for failure. |
196 | If the return value is ENOMEM, that will be translated to EAGAIN, |
197 | so create_thread need not do that. On failure, *THREAD_RAN should |
198 | be set to true iff the thread actually started up and then got |
199 | canceled before calling user code (*PD->start_routine). */ |
200 | static int create_thread (struct pthread *pd, const struct pthread_attr *attr, |
201 | bool *stopped_start, STACK_VARIABLES_PARMS, |
202 | bool *thread_ran); |
203 | |
204 | #include <createthread.c> |
205 | |
206 | |
207 | struct pthread * |
208 | internal_function |
209 | __find_in_stack_list (struct pthread *pd) |
210 | { |
211 | list_t *entry; |
212 | struct pthread *result = NULL; |
213 | |
214 | lll_lock (stack_cache_lock, LLL_PRIVATE); |
215 | |
216 | list_for_each (entry, &stack_used) |
217 | { |
218 | struct pthread *curp; |
219 | |
220 | curp = list_entry (entry, struct pthread, list); |
221 | if (curp == pd) |
222 | { |
223 | result = curp; |
224 | break; |
225 | } |
226 | } |
227 | |
228 | if (result == NULL) |
229 | list_for_each (entry, &__stack_user) |
230 | { |
231 | struct pthread *curp; |
232 | |
233 | curp = list_entry (entry, struct pthread, list); |
234 | if (curp == pd) |
235 | { |
236 | result = curp; |
237 | break; |
238 | } |
239 | } |
240 | |
241 | lll_unlock (stack_cache_lock, LLL_PRIVATE); |
242 | |
243 | return result; |
244 | } |
245 | |
246 | |
247 | /* Deallocate POSIX thread-local-storage. */ |
248 | void |
249 | attribute_hidden |
250 | __nptl_deallocate_tsd (void) |
251 | { |
252 | struct pthread *self = THREAD_SELF; |
253 | |
254 | /* Maybe no data was ever allocated. This happens often so we have |
255 | a flag for this. */ |
256 | if (THREAD_GETMEM (self, specific_used)) |
257 | { |
258 | size_t round; |
259 | size_t cnt; |
260 | |
261 | round = 0; |
262 | do |
263 | { |
264 | size_t idx; |
265 | |
266 | /* So far no new nonzero data entry. */ |
267 | THREAD_SETMEM (self, specific_used, false); |
268 | |
269 | for (cnt = idx = 0; cnt < PTHREAD_KEY_1STLEVEL_SIZE; ++cnt) |
270 | { |
271 | struct pthread_key_data *level2; |
272 | |
273 | level2 = THREAD_GETMEM_NC (self, specific, cnt); |
274 | |
275 | if (level2 != NULL) |
276 | { |
277 | size_t inner; |
278 | |
279 | for (inner = 0; inner < PTHREAD_KEY_2NDLEVEL_SIZE; |
280 | ++inner, ++idx) |
281 | { |
282 | void *data = level2[inner].data; |
283 | |
284 | if (data != NULL) |
285 | { |
286 | /* Always clear the data. */ |
287 | level2[inner].data = NULL; |
288 | |
289 | /* Make sure the data corresponds to a valid |
290 | key. This test fails if the key was |
291 | deallocated and also if it was |
292 | re-allocated. It is the user's |
293 | responsibility to free the memory in this |
294 | case. */ |
295 | if (level2[inner].seq |
296 | == __pthread_keys[idx].seq |
297 | /* It is not necessary to register a destructor |
298 | function. */ |
299 | && __pthread_keys[idx].destr != NULL) |
300 | /* Call the user-provided destructor. */ |
301 | __pthread_keys[idx].destr (data); |
302 | } |
303 | } |
304 | } |
305 | else |
306 | idx += PTHREAD_KEY_1STLEVEL_SIZE; |
307 | } |
308 | |
309 | if (THREAD_GETMEM (self, specific_used) == 0) |
310 | /* No data has been modified. */ |
311 | goto just_free; |
312 | } |
313 | /* We only repeat the process a fixed number of times. */ |
314 | while (__builtin_expect (++round < PTHREAD_DESTRUCTOR_ITERATIONS, 0)); |
315 | |
316 | /* Just clear the memory of the first block for reuse. */ |
317 | memset (&THREAD_SELF->specific_1stblock, '\0', |
318 | sizeof (self->specific_1stblock)); |
319 | |
320 | just_free: |
321 | /* Free the memory for the other blocks. */ |
322 | for (cnt = 1; cnt < PTHREAD_KEY_1STLEVEL_SIZE; ++cnt) |
323 | { |
324 | struct pthread_key_data *level2; |
325 | |
326 | level2 = THREAD_GETMEM_NC (self, specific, cnt); |
327 | if (level2 != NULL) |
328 | { |
329 | /* The first block is allocated as part of the thread |
330 | descriptor. */ |
331 | free (level2); |
332 | THREAD_SETMEM_NC (self, specific, cnt, NULL); |
333 | } |
334 | } |
335 | |
336 | THREAD_SETMEM (self, specific_used, false); |
337 | } |
338 | } |
339 | |
340 | |
341 | /* Deallocate a thread's stack after optionally making sure the thread |
342 | descriptor is still valid. */ |
343 | void |
344 | internal_function |
345 | __free_tcb (struct pthread *pd) |
346 | { |
347 | /* The thread is exiting now. */ |
348 | if (__builtin_expect (atomic_bit_test_set (&pd->cancelhandling, |
349 | TERMINATED_BIT) == 0, 1)) |
350 | { |
351 | /* Remove the descriptor from the list. */ |
352 | if (DEBUGGING_P && __find_in_stack_list (pd) == NULL) |
353 | /* Something is really wrong. The descriptor for a still |
354 | running thread is gone. */ |
355 | abort (); |
356 | |
357 | /* Free TPP data. */ |
358 | if (__glibc_unlikely (pd->tpp != NULL)) |
359 | { |
360 | struct priority_protection_data *tpp = pd->tpp; |
361 | |
362 | pd->tpp = NULL; |
363 | free (tpp); |
364 | } |
365 | |
366 | /* Queue the stack memory block for reuse and exit the process. The |
367 | kernel will signal via writing to the address returned by |
368 | QUEUE-STACK when the stack is available. */ |
369 | __deallocate_stack (pd); |
370 | } |
371 | } |
372 | |
373 | |
374 | /* Local function to start thread and handle cleanup. |
375 | createthread.c defines the macro START_THREAD_DEFN to the |
376 | declaration that its create_thread function will refer to, and |
377 | START_THREAD_SELF to the expression to optimally deliver the new |
378 | thread's THREAD_SELF value. */ |
379 | START_THREAD_DEFN |
380 | { |
381 | struct pthread *pd = START_THREAD_SELF; |
382 | |
383 | #if HP_TIMING_AVAIL |
384 | /* Remember the time when the thread was started. */ |
385 | hp_timing_t now; |
386 | HP_TIMING_NOW (now); |
387 | THREAD_SETMEM (pd, cpuclock_offset, now); |
388 | #endif |
389 | |
390 | /* Initialize resolver state pointer. */ |
391 | __resp = &pd->res; |
392 | |
393 | /* Initialize pointers to locale data. */ |
394 | __ctype_init (); |
395 | |
396 | /* Allow setxid from now onwards. */ |
397 | if (__glibc_unlikely (atomic_exchange_acq (&pd->setxid_futex, 0) == -2)) |
398 | futex_wake (&pd->setxid_futex, 1, FUTEX_PRIVATE); |
399 | |
400 | #ifdef __NR_set_robust_list |
401 | # ifndef __ASSUME_SET_ROBUST_LIST |
402 | if (__set_robust_list_avail >= 0) |
403 | # endif |
404 | { |
405 | INTERNAL_SYSCALL_DECL (err); |
406 | /* This call should never fail because the initial call in init.c |
407 | succeeded. */ |
408 | INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head, |
409 | sizeof (struct robust_list_head)); |
410 | } |
411 | #endif |
412 | |
413 | #ifdef SIGCANCEL |
414 | /* If the parent was running cancellation handlers while creating |
415 | the thread the new thread inherited the signal mask. Reset the |
416 | cancellation signal mask. */ |
417 | if (__glibc_unlikely (pd->parent_cancelhandling & CANCELING_BITMASK)) |
418 | { |
419 | INTERNAL_SYSCALL_DECL (err); |
420 | sigset_t mask; |
421 | __sigemptyset (&mask); |
422 | __sigaddset (&mask, SIGCANCEL); |
423 | (void) INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_UNBLOCK, &mask, |
424 | NULL, _NSIG / 8); |
425 | } |
426 | #endif |
427 | |
428 | /* This is where the try/finally block should be created. For |
429 | compilers without that support we do use setjmp. */ |
430 | struct pthread_unwind_buf unwind_buf; |
431 | |
432 | /* No previous handlers. */ |
433 | unwind_buf.priv.data.prev = NULL; |
434 | unwind_buf.priv.data.cleanup = NULL; |
435 | |
436 | int not_first_call; |
437 | not_first_call = setjmp ((struct __jmp_buf_tag *) unwind_buf.cancel_jmp_buf); |
438 | if (__glibc_likely (! not_first_call)) |
439 | { |
440 | /* Store the new cleanup handler info. */ |
441 | THREAD_SETMEM (pd, cleanup_jmp_buf, &unwind_buf); |
442 | |
443 | /* We are either in (a) or (b), and in either case we either own |
444 | PD already (2) or are about to own PD (1), and so our only |
445 | restriction would be that we can't free PD until we know we |
446 | have ownership (see CONCURRENCY NOTES above). */ |
447 | if (__glibc_unlikely (pd->stopped_start)) |
448 | { |
449 | int oldtype = CANCEL_ASYNC (); |
450 | |
451 | /* Get the lock the parent locked to force synchronization. */ |
452 | lll_lock (pd->lock, LLL_PRIVATE); |
453 | |
454 | /* We have ownership of PD now. */ |
455 | |
456 | /* And give it up right away. */ |
457 | lll_unlock (pd->lock, LLL_PRIVATE); |
458 | |
459 | CANCEL_RESET (oldtype); |
460 | } |
461 | |
462 | LIBC_PROBE (pthread_start, 3, (pthread_t) pd, pd->start_routine, pd->arg); |
463 | |
464 | /* Run the code the user provided. */ |
465 | THREAD_SETMEM (pd, result, pd->start_routine (pd->arg)); |
466 | } |
467 | |
468 | /* Call destructors for the thread_local TLS variables. */ |
469 | #ifndef SHARED |
470 | if (&__call_tls_dtors != NULL) |
471 | #endif |
472 | __call_tls_dtors (); |
473 | |
474 | /* Run the destructor for the thread-local data. */ |
475 | __nptl_deallocate_tsd (); |
476 | |
477 | /* Clean up any state libc stored in thread-local variables. */ |
478 | __libc_thread_freeres (); |
479 | |
480 | /* If this is the last thread we terminate the process now. We |
481 | do not notify the debugger, it might just irritate it if there |
482 | is no thread left. */ |
483 | if (__glibc_unlikely (atomic_decrement_and_test (&__nptl_nthreads))) |
484 | /* This was the last thread. */ |
485 | exit (0); |
486 | |
487 | /* Report the death of the thread if this is wanted. */ |
488 | if (__glibc_unlikely (pd->report_events)) |
489 | { |
490 | /* See whether TD_DEATH is in any of the mask. */ |
491 | const int idx = __td_eventword (TD_DEATH); |
492 | const uint32_t mask = __td_eventmask (TD_DEATH); |
493 | |
494 | if ((mask & (__nptl_threads_events.event_bits[idx] |
495 | | pd->eventbuf.eventmask.event_bits[idx])) != 0) |
496 | { |
497 | /* Yep, we have to signal the death. Add the descriptor to |
498 | the list but only if it is not already on it. */ |
499 | if (pd->nextevent == NULL) |
500 | { |
501 | pd->eventbuf.eventnum = TD_DEATH; |
502 | pd->eventbuf.eventdata = pd; |
503 | |
504 | do |
505 | pd->nextevent = __nptl_last_event; |
506 | while (atomic_compare_and_exchange_bool_acq (&__nptl_last_event, |
507 | pd, pd->nextevent)); |
508 | } |
509 | |
510 | /* Now call the function which signals the event. See |
511 | CONCURRENCY NOTES for the nptl_db interface comments. */ |
512 | __nptl_death_event (); |
513 | } |
514 | } |
515 | |
516 | /* The thread is exiting now. Don't set this bit until after we've hit |
517 | the event-reporting breakpoint, so that td_thr_get_info on us while at |
518 | the breakpoint reports TD_THR_RUN state rather than TD_THR_ZOMBIE. */ |
519 | atomic_bit_set (&pd->cancelhandling, EXITING_BIT); |
520 | |
521 | #ifndef __ASSUME_SET_ROBUST_LIST |
522 | /* If this thread has any robust mutexes locked, handle them now. */ |
523 | # if __PTHREAD_MUTEX_HAVE_PREV |
524 | void *robust = pd->robust_head.list; |
525 | # else |
526 | __pthread_slist_t *robust = pd->robust_list.__next; |
527 | # endif |
528 | /* We let the kernel do the notification if it is able to do so. |
529 | If we have to do it here there for sure are no PI mutexes involved |
530 | since the kernel support for them is even more recent. */ |
531 | if (__set_robust_list_avail < 0 |
532 | && __builtin_expect (robust != (void *) &pd->robust_head, 0)) |
533 | { |
534 | do |
535 | { |
536 | struct __pthread_mutex_s *this = (struct __pthread_mutex_s *) |
537 | ((char *) robust - offsetof (struct __pthread_mutex_s, |
538 | __list.__next)); |
539 | robust = *((void **) robust); |
540 | |
541 | # if __PTHREAD_MUTEX_HAVE_PREV |
542 | this->__list.__prev = NULL; |
543 | # endif |
544 | this->__list.__next = NULL; |
545 | |
546 | atomic_or (&this->__lock, FUTEX_OWNER_DIED); |
547 | futex_wake ((unsigned int *) &this->__lock, 1, |
548 | /* XYZ */ FUTEX_SHARED); |
549 | } |
550 | while (robust != (void *) &pd->robust_head); |
551 | } |
552 | #endif |
553 | |
554 | advise_stack_range (pd->stackblock, pd->stackblock_size, (uintptr_t) pd, |
555 | pd->guardsize); |
556 | |
557 | /* If the thread is detached free the TCB. */ |
558 | if (IS_DETACHED (pd)) |
559 | /* Free the TCB. */ |
560 | __free_tcb (pd); |
561 | else if (__glibc_unlikely (pd->cancelhandling & SETXID_BITMASK)) |
562 | { |
563 | /* Some other thread might call any of the setXid functions and expect |
564 | us to reply. In this case wait until we did that. */ |
565 | do |
566 | /* XXX This differs from the typical futex_wait_simple pattern in that |
567 | the futex_wait condition (setxid_futex) is different from the |
568 | condition used in the surrounding loop (cancelhandling). We need |
569 | to check and document why this is correct. */ |
570 | futex_wait_simple (&pd->setxid_futex, 0, FUTEX_PRIVATE); |
571 | while (pd->cancelhandling & SETXID_BITMASK); |
572 | |
573 | /* Reset the value so that the stack can be reused. */ |
574 | pd->setxid_futex = 0; |
575 | } |
576 | |
577 | /* We cannot call '_exit' here. '_exit' will terminate the process. |
578 | |
579 | The 'exit' implementation in the kernel will signal when the |
580 | process is really dead since 'clone' got passed the CLONE_CHILD_CLEARTID |
581 | flag. The 'tid' field in the TCB will be set to zero. |
582 | |
583 | The exit code is zero since in case all threads exit by calling |
584 | 'pthread_exit' the exit status must be 0 (zero). */ |
585 | __exit_thread (); |
586 | |
587 | /* NOTREACHED */ |
588 | } |
589 | |
590 | |
591 | /* Return true iff obliged to report TD_CREATE events. */ |
592 | static bool |
593 | report_thread_creation (struct pthread *pd) |
594 | { |
595 | if (__glibc_unlikely (THREAD_GETMEM (THREAD_SELF, report_events))) |
596 | { |
597 | /* The parent thread is supposed to report events. |
598 | Check whether the TD_CREATE event is needed, too. */ |
599 | const size_t idx = __td_eventword (TD_CREATE); |
600 | const uint32_t mask = __td_eventmask (TD_CREATE); |
601 | |
602 | return ((mask & (__nptl_threads_events.event_bits[idx] |
603 | | pd->eventbuf.eventmask.event_bits[idx])) != 0); |
604 | } |
605 | return false; |
606 | } |
607 | |
608 | |
609 | int |
610 | __pthread_create_2_1 (pthread_t *newthread, const pthread_attr_t *attr, |
611 | void *(*start_routine) (void *), void *arg) |
612 | { |
613 | STACK_VARIABLES; |
614 | |
615 | const struct pthread_attr *iattr = (struct pthread_attr *) attr; |
616 | struct pthread_attr default_attr; |
617 | bool free_cpuset = false; |
618 | if (iattr == NULL) |
619 | { |
620 | lll_lock (__default_pthread_attr_lock, LLL_PRIVATE); |
621 | default_attr = __default_pthread_attr; |
622 | size_t cpusetsize = default_attr.cpusetsize; |
623 | if (cpusetsize > 0) |
624 | { |
625 | cpu_set_t *cpuset; |
626 | if (__glibc_likely (__libc_use_alloca (cpusetsize))) |
627 | cpuset = __alloca (cpusetsize); |
628 | else |
629 | { |
630 | cpuset = malloc (cpusetsize); |
631 | if (cpuset == NULL) |
632 | { |
633 | lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE); |
634 | return ENOMEM; |
635 | } |
636 | free_cpuset = true; |
637 | } |
638 | memcpy (cpuset, default_attr.cpuset, cpusetsize); |
639 | default_attr.cpuset = cpuset; |
640 | } |
641 | lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE); |
642 | iattr = &default_attr; |
643 | } |
644 | |
645 | struct pthread *pd = NULL; |
646 | int err = ALLOCATE_STACK (iattr, &pd); |
647 | int retval = 0; |
648 | |
649 | if (__glibc_unlikely (err != 0)) |
650 | /* Something went wrong. Maybe a parameter of the attributes is |
651 | invalid or we could not allocate memory. Note we have to |
652 | translate error codes. */ |
653 | { |
654 | retval = err == ENOMEM ? EAGAIN : err; |
655 | goto out; |
656 | } |
657 | |
658 | |
659 | /* Initialize the TCB. All initializations with zero should be |
660 | performed in 'get_cached_stack'. This way we avoid doing this if |
661 | the stack freshly allocated with 'mmap'. */ |
662 | |
663 | #if TLS_TCB_AT_TP |
664 | /* Reference to the TCB itself. */ |
665 | pd->header.self = pd; |
666 | |
667 | /* Self-reference for TLS. */ |
668 | pd->header.tcb = pd; |
669 | #endif |
670 | |
671 | /* Store the address of the start routine and the parameter. Since |
672 | we do not start the function directly the stillborn thread will |
673 | get the information from its thread descriptor. */ |
674 | pd->start_routine = start_routine; |
675 | pd->arg = arg; |
676 | |
677 | /* Copy the thread attribute flags. */ |
678 | struct pthread *self = THREAD_SELF; |
679 | pd->flags = ((iattr->flags & ~(ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET)) |
680 | | (self->flags & (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET))); |
681 | |
682 | /* Initialize the field for the ID of the thread which is waiting |
683 | for us. This is a self-reference in case the thread is created |
684 | detached. */ |
685 | pd->joinid = iattr->flags & ATTR_FLAG_DETACHSTATE ? pd : NULL; |
686 | |
687 | /* The debug events are inherited from the parent. */ |
688 | pd->eventbuf = self->eventbuf; |
689 | |
690 | |
691 | /* Copy the parent's scheduling parameters. The flags will say what |
692 | is valid and what is not. */ |
693 | pd->schedpolicy = self->schedpolicy; |
694 | pd->schedparam = self->schedparam; |
695 | |
696 | /* Copy the stack guard canary. */ |
697 | #ifdef THREAD_COPY_STACK_GUARD |
698 | THREAD_COPY_STACK_GUARD (pd); |
699 | #endif |
700 | |
701 | /* Copy the pointer guard value. */ |
702 | #ifdef THREAD_COPY_POINTER_GUARD |
703 | THREAD_COPY_POINTER_GUARD (pd); |
704 | #endif |
705 | |
706 | /* Verify the sysinfo bits were copied in allocate_stack if needed. */ |
707 | #ifdef NEED_DL_SYSINFO |
708 | CHECK_THREAD_SYSINFO (pd); |
709 | #endif |
710 | |
711 | /* Inform start_thread (above) about cancellation state that might |
712 | translate into inherited signal state. */ |
713 | pd->parent_cancelhandling = THREAD_GETMEM (THREAD_SELF, cancelhandling); |
714 | |
715 | /* Determine scheduling parameters for the thread. */ |
716 | if (__builtin_expect ((iattr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0, 0) |
717 | && (iattr->flags & (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET)) != 0) |
718 | { |
719 | /* Use the scheduling parameters the user provided. */ |
720 | if (iattr->flags & ATTR_FLAG_POLICY_SET) |
721 | { |
722 | pd->schedpolicy = iattr->schedpolicy; |
723 | pd->flags |= ATTR_FLAG_POLICY_SET; |
724 | } |
725 | if (iattr->flags & ATTR_FLAG_SCHED_SET) |
726 | { |
727 | /* The values were validated in pthread_attr_setschedparam. */ |
728 | pd->schedparam = iattr->schedparam; |
729 | pd->flags |= ATTR_FLAG_SCHED_SET; |
730 | } |
731 | |
732 | if ((pd->flags & (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET)) |
733 | != (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET)) |
734 | collect_default_sched (pd); |
735 | } |
736 | |
737 | if (__glibc_unlikely (__nptl_nthreads == 1)) |
738 | _IO_enable_locks (); |
739 | |
740 | /* Pass the descriptor to the caller. */ |
741 | *newthread = (pthread_t) pd; |
742 | |
743 | LIBC_PROBE (pthread_create, 4, newthread, attr, start_routine, arg); |
744 | |
745 | /* One more thread. We cannot have the thread do this itself, since it |
746 | might exist but not have been scheduled yet by the time we've returned |
747 | and need to check the value to behave correctly. We must do it before |
748 | creating the thread, in case it does get scheduled first and then |
749 | might mistakenly think it was the only thread. In the failure case, |
750 | we momentarily store a false value; this doesn't matter because there |
751 | is no kosher thing a signal handler interrupting us right here can do |
752 | that cares whether the thread count is correct. */ |
753 | atomic_increment (&__nptl_nthreads); |
754 | |
755 | /* Our local value of stopped_start and thread_ran can be accessed at |
756 | any time. The PD->stopped_start may only be accessed if we have |
757 | ownership of PD (see CONCURRENCY NOTES above). */ |
758 | bool stopped_start = false; bool thread_ran = false; |
759 | |
760 | /* Start the thread. */ |
761 | if (__glibc_unlikely (report_thread_creation (pd))) |
762 | { |
763 | stopped_start = true; |
764 | |
765 | /* We always create the thread stopped at startup so we can |
766 | notify the debugger. */ |
767 | retval = create_thread (pd, iattr, &stopped_start, |
768 | STACK_VARIABLES_ARGS, &thread_ran); |
769 | if (retval == 0) |
770 | { |
771 | /* We retain ownership of PD until (a) (see CONCURRENCY NOTES |
772 | above). */ |
773 | |
774 | /* Assert stopped_start is true in both our local copy and the |
775 | PD copy. */ |
776 | assert (stopped_start); |
777 | assert (pd->stopped_start); |
778 | |
779 | /* Now fill in the information about the new thread in |
780 | the newly created thread's data structure. We cannot let |
781 | the new thread do this since we don't know whether it was |
782 | already scheduled when we send the event. */ |
783 | pd->eventbuf.eventnum = TD_CREATE; |
784 | pd->eventbuf.eventdata = pd; |
785 | |
786 | /* Enqueue the descriptor. */ |
787 | do |
788 | pd->nextevent = __nptl_last_event; |
789 | while (atomic_compare_and_exchange_bool_acq (&__nptl_last_event, |
790 | pd, pd->nextevent) |
791 | != 0); |
792 | |
793 | /* Now call the function which signals the event. See |
794 | CONCURRENCY NOTES for the nptl_db interface comments. */ |
795 | __nptl_create_event (); |
796 | } |
797 | } |
798 | else |
799 | retval = create_thread (pd, iattr, &stopped_start, |
800 | STACK_VARIABLES_ARGS, &thread_ran); |
801 | |
802 | if (__glibc_unlikely (retval != 0)) |
803 | { |
804 | if (thread_ran) |
805 | /* State (c) or (d) and we may not have PD ownership (see |
806 | CONCURRENCY NOTES above). We can assert that STOPPED_START |
807 | must have been true because thread creation didn't fail, but |
808 | thread attribute setting did. */ |
809 | /* See bug 19511 which explains why doing nothing here is a |
810 | resource leak for a joinable thread. */ |
811 | assert (stopped_start); |
812 | else |
813 | { |
814 | /* State (e) and we have ownership of PD (see CONCURRENCY |
815 | NOTES above). */ |
816 | |
817 | /* Oops, we lied for a second. */ |
818 | atomic_decrement (&__nptl_nthreads); |
819 | |
820 | /* Perhaps a thread wants to change the IDs and is waiting for this |
821 | stillborn thread. */ |
822 | if (__glibc_unlikely (atomic_exchange_acq (&pd->setxid_futex, 0) |
823 | == -2)) |
824 | futex_wake (&pd->setxid_futex, 1, FUTEX_PRIVATE); |
825 | |
826 | /* Free the resources. */ |
827 | __deallocate_stack (pd); |
828 | } |
829 | |
830 | /* We have to translate error codes. */ |
831 | if (retval == ENOMEM) |
832 | retval = EAGAIN; |
833 | } |
834 | else |
835 | { |
836 | /* We don't know if we have PD ownership. Once we check the local |
837 | stopped_start we'll know if we're in state (a) or (b) (see |
838 | CONCURRENCY NOTES above). */ |
839 | if (stopped_start) |
840 | /* State (a), we own PD. The thread blocked on this lock either |
841 | because we're doing TD_CREATE event reporting, or for some |
842 | other reason that create_thread chose. Now let it run |
843 | free. */ |
844 | lll_unlock (pd->lock, LLL_PRIVATE); |
845 | |
846 | /* We now have for sure more than one thread. The main thread might |
847 | not yet have the flag set. No need to set the global variable |
848 | again if this is what we use. */ |
849 | THREAD_SETMEM (THREAD_SELF, header.multiple_threads, 1); |
850 | } |
851 | |
852 | out: |
853 | if (__glibc_unlikely (free_cpuset)) |
854 | free (default_attr.cpuset); |
855 | |
856 | return retval; |
857 | } |
858 | versioned_symbol (libpthread, __pthread_create_2_1, pthread_create, GLIBC_2_1); |
859 | |
860 | |
861 | #if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_1) |
862 | int |
863 | __pthread_create_2_0 (pthread_t *newthread, const pthread_attr_t *attr, |
864 | void *(*start_routine) (void *), void *arg) |
865 | { |
866 | /* The ATTR attribute is not really of type `pthread_attr_t *'. It has |
867 | the old size and access to the new members might crash the program. |
868 | We convert the struct now. */ |
869 | struct pthread_attr new_attr; |
870 | |
871 | if (attr != NULL) |
872 | { |
873 | struct pthread_attr *iattr = (struct pthread_attr *) attr; |
874 | size_t ps = __getpagesize (); |
875 | |
876 | /* Copy values from the user-provided attributes. */ |
877 | new_attr.schedparam = iattr->schedparam; |
878 | new_attr.schedpolicy = iattr->schedpolicy; |
879 | new_attr.flags = iattr->flags; |
880 | |
881 | /* Fill in default values for the fields not present in the old |
882 | implementation. */ |
883 | new_attr.guardsize = ps; |
884 | new_attr.stackaddr = NULL; |
885 | new_attr.stacksize = 0; |
886 | new_attr.cpuset = NULL; |
887 | |
888 | /* We will pass this value on to the real implementation. */ |
889 | attr = (pthread_attr_t *) &new_attr; |
890 | } |
891 | |
892 | return __pthread_create_2_1 (newthread, attr, start_routine, arg); |
893 | } |
894 | compat_symbol (libpthread, __pthread_create_2_0, pthread_create, |
895 | GLIBC_2_0); |
896 | #endif |
897 | |
898 | /* Information for libthread_db. */ |
899 | |
900 | #include "../nptl_db/db_info.c" |
901 | |
902 | /* If pthread_create is present, libgcc_eh.a and libsupc++.a expects some other POSIX thread |
903 | functions to be present as well. */ |
904 | PTHREAD_STATIC_FN_REQUIRE (__pthread_mutex_lock) |
905 | PTHREAD_STATIC_FN_REQUIRE (__pthread_mutex_trylock) |
906 | PTHREAD_STATIC_FN_REQUIRE (__pthread_mutex_unlock) |
907 | |
908 | PTHREAD_STATIC_FN_REQUIRE (__pthread_once) |
909 | PTHREAD_STATIC_FN_REQUIRE (__pthread_cancel) |
910 | |
911 | PTHREAD_STATIC_FN_REQUIRE (__pthread_key_create) |
912 | PTHREAD_STATIC_FN_REQUIRE (__pthread_key_delete) |
913 | PTHREAD_STATIC_FN_REQUIRE (__pthread_setspecific) |
914 | PTHREAD_STATIC_FN_REQUIRE (__pthread_getspecific) |
915 | |