1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941
|
/* Copyright (C) 2002-2018 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <ctype.h>
#include <errno.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include "pthreadP.h"
#include <hp-timing.h>
#include <ldsodefs.h>
#include <atomic.h>
#include <libc-internal.h>
#include <resolv.h>
#include <kernel-features.h>
#include <exit-thread.h>
#include <default-sched.h>
#include <futex-internal.h>
#include <tls-setup.h>
#include "libioP.h"
#include <shlib-compat.h>
#include <stap-probe.h>
/* Nozero if debugging mode is enabled. */
int __pthread_debug;
/* Globally enabled events. */
static td_thr_events_t __nptl_threads_events __attribute_used__;
/* Pointer to descriptor with the last event. */
static struct pthread *__nptl_last_event __attribute_used__;
/* Number of threads running. */
unsigned int __nptl_nthreads = 1;
/* Code to allocate and deallocate a stack. */
#include "allocatestack.c"
/* CONCURRENCY NOTES:
Understanding who is the owner of the 'struct pthread' or 'PD'
(refers to the value of the 'struct pthread *pd' function argument)
is critically important in determining exactly which operations are
allowed and which are not and when, particularly when it comes to the
implementation of pthread_create, pthread_join, pthread_detach, and
other functions which all operate on PD.
The owner of PD is responsible for freeing the final resources
associated with PD, and may examine the memory underlying PD at any
point in time until it frees it back to the OS or to reuse by the
runtime.
The thread which calls pthread_create is called the creating thread.
The creating thread begins as the owner of PD.
During startup the new thread may examine PD in coordination with the
owner thread (which may be itself).
The four cases of ownership transfer are:
(1) Ownership of PD is released to the process (all threads may use it)
after the new thread starts in a joinable state
i.e. pthread_create returns a usable pthread_t.
(2) Ownership of PD is released to the new thread starting in a detached
state.
(3) Ownership of PD is dynamically released to a running thread via
pthread_detach.
(4) Ownership of PD is acquired by the thread which calls pthread_join.
Implementation notes:
The PD->stopped_start and thread_ran variables are used to determine
exactly which of the four ownership states we are in and therefore
what actions can be taken. For example after (2) we cannot read or
write from PD anymore since the thread may no longer exist and the
memory may be unmapped.
It is important to point out that PD->lock is being used both
similar to a one-shot semaphore and subsequently as a mutex. The
lock is taken in the parent to force the child to wait, and then the
child releases the lock. However, this semaphore-like effect is used
only for synchronizing the parent and child. After startup the lock
is used like a mutex to create a critical section during which a
single owner modifies the thread parameters.
The most complicated cases happen during thread startup:
(a) If the created thread is in a detached (PTHREAD_CREATE_DETACHED),
or joinable (default PTHREAD_CREATE_JOINABLE) state and
STOPPED_START is true, then the creating thread has ownership of
PD until the PD->lock is released by pthread_create. If any
errors occur we are in states (c), (d), or (e) below.
(b) If the created thread is in a detached state
(PTHREAD_CREATED_DETACHED), and STOPPED_START is false, then the
creating thread has ownership of PD until it invokes the OS
kernel's thread creation routine. If this routine returns
without error, then the created thread owns PD; otherwise, see
(c) and (e) below.
(c) If the detached thread setup failed and THREAD_RAN is true, then
the creating thread releases ownership to the new thread by
sending a cancellation signal. All threads set THREAD_RAN to
true as quickly as possible after returning from the OS kernel's
thread creation routine.
(d) If the joinable thread setup failed and THREAD_RAN is true, then
then the creating thread retains ownership of PD and must cleanup
state. Ownership cannot be released to the process via the
return of pthread_create since a non-zero result entails PD is
undefined and therefore cannot be joined to free the resources.
We privately call pthread_join on the thread to finish handling
the resource shutdown (Or at least we should, see bug 19511).
(e) If the thread creation failed and THREAD_RAN is false, then the
creating thread retains ownership of PD and must cleanup state.
No waiting for the new thread is required because it never
started.
The nptl_db interface:
The interface with nptl_db requires that we enqueue PD into a linked
list and then call a function which the debugger will trap. The PD
will then be dequeued and control returned to the thread. The caller
at the time must have ownership of PD and such ownership remains
after control returns to thread. The enqueued PD is removed from the
linked list by the nptl_db callback td_thr_event_getmsg. The debugger
must ensure that the thread does not resume execution, otherwise
ownership of PD may be lost and examining PD will not be possible.
Note that the GNU Debugger as of (December 10th 2015) commit
c2c2a31fdb228d41ce3db62b268efea04bd39c18 no longer uses
td_thr_event_getmsg and several other related nptl_db interfaces. The
principal reason for this is that nptl_db does not support non-stop
mode where other threads can run concurrently and modify runtime
structures currently in use by the debugger and the nptl_db
interface.
Axioms:
* The create_thread function can never set stopped_start to false.
* The created thread can read stopped_start but never write to it.
* The variable thread_ran is set some time after the OS thread
creation routine returns, how much time after the thread is created
is unspecified, but it should be as quickly as possible.
*/
/* CREATE THREAD NOTES:
createthread.c defines the create_thread function, and two macros:
START_THREAD_DEFN and START_THREAD_SELF (see below).
create_thread must initialize PD->stopped_start. It should be true
if the STOPPED_START parameter is true, or if create_thread needs the
new thread to synchronize at startup for some other implementation
reason. If STOPPED_START will be true, then create_thread is obliged
to lock PD->lock before starting the thread. Then pthread_create
unlocks PD->lock which synchronizes-with START_THREAD_DEFN in the
child thread which does an acquire/release of PD->lock as the last
action before calling the user entry point. The goal of all of this
is to ensure that the required initial thread attributes are applied
(by the creating thread) before the new thread runs user code. Note
that the the functions pthread_getschedparam, pthread_setschedparam,
pthread_setschedprio, __pthread_tpp_change_priority, and
__pthread_current_priority reuse the same lock, PD->lock, for a
similar purpose e.g. synchronizing the setting of similar thread
attributes. These functions are never called before the thread is
created, so don't participate in startup syncronization, but given
that the lock is present already and in the unlocked state, reusing
it saves space.
The return value is zero for success or an errno code for failure.
If the return value is ENOMEM, that will be translated to EAGAIN,
so create_thread need not do that. On failure, *THREAD_RAN should
be set to true iff the thread actually started up and then got
canceled before calling user code (*PD->start_routine). */
static int create_thread (struct pthread *pd, const struct pthread_attr *attr,
bool *stopped_start, STACK_VARIABLES_PARMS,
bool *thread_ran);
#include <createthread.c>
struct pthread *
__find_in_stack_list (struct pthread *pd)
{
list_t *entry;
struct pthread *result = NULL;
lll_lock (stack_cache_lock, LLL_PRIVATE);
list_for_each (entry, &stack_used)
{
struct pthread *curp;
curp = list_entry (entry, struct pthread, list);
if (curp == pd)
{
result = curp;
break;
}
}
if (result == NULL)
list_for_each (entry, &__stack_user)
{
struct pthread *curp;
curp = list_entry (entry, struct pthread, list);
if (curp == pd)
{
result = curp;
break;
}
}
lll_unlock (stack_cache_lock, LLL_PRIVATE);
return result;
}
/* Deallocate POSIX thread-local-storage. */
void
attribute_hidden
__nptl_deallocate_tsd (void)
{
struct pthread *self = THREAD_SELF;
/* Maybe no data was ever allocated. This happens often so we have
a flag for this. */
if (THREAD_GETMEM (self, specific_used))
{
size_t round;
size_t cnt;
round = 0;
do
{
size_t idx;
/* So far no new nonzero data entry. */
THREAD_SETMEM (self, specific_used, false);
for (cnt = idx = 0; cnt < PTHREAD_KEY_1STLEVEL_SIZE; ++cnt)
{
struct pthread_key_data *level2;
level2 = THREAD_GETMEM_NC (self, specific, cnt);
if (level2 != NULL)
{
size_t inner;
for (inner = 0; inner < PTHREAD_KEY_2NDLEVEL_SIZE;
++inner, ++idx)
{
void *data = level2[inner].data;
if (data != NULL)
{
/* Always clear the data. */
level2[inner].data = NULL;
/* Make sure the data corresponds to a valid
key. This test fails if the key was
deallocated and also if it was
re-allocated. It is the user's
responsibility to free the memory in this
case. */
if (level2[inner].seq
== __pthread_keys[idx].seq
/* It is not necessary to register a destructor
function. */
&& __pthread_keys[idx].destr != NULL)
/* Call the user-provided destructor. */
__pthread_keys[idx].destr (data);
}
}
}
else
idx += PTHREAD_KEY_1STLEVEL_SIZE;
}
if (THREAD_GETMEM (self, specific_used) == 0)
/* No data has been modified. */
goto just_free;
}
/* We only repeat the process a fixed number of times. */
while (__builtin_expect (++round < PTHREAD_DESTRUCTOR_ITERATIONS, 0));
/* Just clear the memory of the first block for reuse. */
memset (&THREAD_SELF->specific_1stblock, '\0',
sizeof (self->specific_1stblock));
just_free:
/* Free the memory for the other blocks. */
for (cnt = 1; cnt < PTHREAD_KEY_1STLEVEL_SIZE; ++cnt)
{
struct pthread_key_data *level2;
level2 = THREAD_GETMEM_NC (self, specific, cnt);
if (level2 != NULL)
{
/* The first block is allocated as part of the thread
descriptor. */
free (level2);
THREAD_SETMEM_NC (self, specific, cnt, NULL);
}
}
THREAD_SETMEM (self, specific_used, false);
}
}
/* Deallocate a thread's stack after optionally making sure the thread
descriptor is still valid. */
void
__free_tcb (struct pthread *pd)
{
/* The thread is exiting now. */
if (__builtin_expect (atomic_bit_test_set (&pd->cancelhandling,
TERMINATED_BIT) == 0, 1))
{
/* Remove the descriptor from the list. */
if (DEBUGGING_P && __find_in_stack_list (pd) == NULL)
/* Something is really wrong. The descriptor for a still
running thread is gone. */
abort ();
/* Free TPP data. */
if (__glibc_unlikely (pd->tpp != NULL))
{
struct priority_protection_data *tpp = pd->tpp;
pd->tpp = NULL;
free (tpp);
}
/* Queue the stack memory block for reuse and exit the process. The
kernel will signal via writing to the address returned by
QUEUE-STACK when the stack is available. */
__deallocate_stack (pd);
}
}
/* Local function to start thread and handle cleanup.
createthread.c defines the macro START_THREAD_DEFN to the
declaration that its create_thread function will refer to, and
START_THREAD_SELF to the expression to optimally deliver the new
thread's THREAD_SELF value. */
START_THREAD_DEFN
{
struct pthread *pd = START_THREAD_SELF;
#if HP_TIMING_AVAIL
/* Remember the time when the thread was started. */
hp_timing_t now;
HP_TIMING_NOW (now);
THREAD_SETMEM (pd, cpuclock_offset, now);
#endif
/* Initialize resolver state pointer. */
__resp = &pd->res;
/* Initialize pointers to locale data. */
__ctype_init ();
/* Allow setxid from now onwards. */
if (__glibc_unlikely (atomic_exchange_acq (&pd->setxid_futex, 0) == -2))
futex_wake (&pd->setxid_futex, 1, FUTEX_PRIVATE);
#ifdef __NR_set_robust_list
# ifndef __ASSUME_SET_ROBUST_LIST
if (__set_robust_list_avail >= 0)
# endif
{
INTERNAL_SYSCALL_DECL (err);
/* This call should never fail because the initial call in init.c
succeeded. */
INTERNAL_SYSCALL (set_robust_list, err, 2, &pd->robust_head,
sizeof (struct robust_list_head));
}
#endif
#ifdef SIGCANCEL
/* If the parent was running cancellation handlers while creating
the thread the new thread inherited the signal mask. Reset the
cancellation signal mask. */
if (__glibc_unlikely (pd->parent_cancelhandling & CANCELING_BITMASK))
{
INTERNAL_SYSCALL_DECL (err);
sigset_t mask;
__sigemptyset (&mask);
__sigaddset (&mask, SIGCANCEL);
(void) INTERNAL_SYSCALL (rt_sigprocmask, err, 4, SIG_UNBLOCK, &mask,
NULL, _NSIG / 8);
}
#endif
/* This is where the try/finally block should be created. For
compilers without that support we do use setjmp. */
struct pthread_unwind_buf unwind_buf;
int not_first_call;
not_first_call = setjmp ((struct __jmp_buf_tag *) unwind_buf.cancel_jmp_buf);
/* No previous handlers. NB: This must be done after setjmp since the
private space in the unwind jump buffer may overlap space used by
setjmp to store extra architecture-specific information which is
never used by the cancellation-specific __libc_unwind_longjmp.
The private space is allowed to overlap because the unwinder never
has to return through any of the jumped-to call frames, and thus
only a minimum amount of saved data need be stored, and for example,
need not include the process signal mask information. This is all
an optimization to reduce stack usage when pushing cancellation
handlers. */
unwind_buf.priv.data.prev = NULL;
unwind_buf.priv.data.cleanup = NULL;
if (__glibc_likely (! not_first_call))
{
/* Store the new cleanup handler info. */
THREAD_SETMEM (pd, cleanup_jmp_buf, &unwind_buf);
/* We are either in (a) or (b), and in either case we either own
PD already (2) or are about to own PD (1), and so our only
restriction would be that we can't free PD until we know we
have ownership (see CONCURRENCY NOTES above). */
if (__glibc_unlikely (pd->stopped_start))
{
int oldtype = CANCEL_ASYNC ();
/* Get the lock the parent locked to force synchronization. */
lll_lock (pd->lock, LLL_PRIVATE);
/* We have ownership of PD now. */
/* And give it up right away. */
lll_unlock (pd->lock, LLL_PRIVATE);
CANCEL_RESET (oldtype);
}
LIBC_PROBE (pthread_start, 3, (pthread_t) pd, pd->start_routine, pd->arg);
/* Run the code the user provided. */
void *ret;
if (pd->c11)
{
/* The function pointer of the c11 thread start is cast to an incorrect
type on __pthread_create_2_1 call, however it is casted back to correct
one so the call behavior is well-defined (it is assumed that pointers
to void are able to represent all values of int. */
int (*start)(void*) = (int (*) (void*)) pd->start_routine;
ret = (void*) (uintptr_t) start (pd->arg);
}
else
ret = pd->start_routine (pd->arg);
THREAD_SETMEM (pd, result, ret);
}
/* Call destructors for the thread_local TLS variables. */
#ifndef SHARED
if (&__call_tls_dtors != NULL)
#endif
__call_tls_dtors ();
/* Run the destructor for the thread-local data. */
__nptl_deallocate_tsd ();
/* Clean up any state libc stored in thread-local variables. */
__libc_thread_freeres ();
/* If this is the last thread we terminate the process now. We
do not notify the debugger, it might just irritate it if there
is no thread left. */
if (__glibc_unlikely (atomic_decrement_and_test (&__nptl_nthreads)))
/* This was the last thread. */
exit (0);
/* Report the death of the thread if this is wanted. */
if (__glibc_unlikely (pd->report_events))
{
/* See whether TD_DEATH is in any of the mask. */
const int idx = __td_eventword (TD_DEATH);
const uint32_t mask = __td_eventmask (TD_DEATH);
if ((mask & (__nptl_threads_events.event_bits[idx]
| pd->eventbuf.eventmask.event_bits[idx])) != 0)
{
/* Yep, we have to signal the death. Add the descriptor to
the list but only if it is not already on it. */
if (pd->nextevent == NULL)
{
pd->eventbuf.eventnum = TD_DEATH;
pd->eventbuf.eventdata = pd;
do
pd->nextevent = __nptl_last_event;
while (atomic_compare_and_exchange_bool_acq (&__nptl_last_event,
pd, pd->nextevent));
}
/* Now call the function which signals the event. See
CONCURRENCY NOTES for the nptl_db interface comments. */
__nptl_death_event ();
}
}
/* The thread is exiting now. Don't set this bit until after we've hit
the event-reporting breakpoint, so that td_thr_get_info on us while at
the breakpoint reports TD_THR_RUN state rather than TD_THR_ZOMBIE. */
atomic_bit_set (&pd->cancelhandling, EXITING_BIT);
#ifndef __ASSUME_SET_ROBUST_LIST
/* If this thread has any robust mutexes locked, handle them now. */
# if __PTHREAD_MUTEX_HAVE_PREV
void *robust = pd->robust_head.list;
# else
__pthread_slist_t *robust = pd->robust_list.__next;
# endif
/* We let the kernel do the notification if it is able to do so.
If we have to do it here there for sure are no PI mutexes involved
since the kernel support for them is even more recent. */
if (__set_robust_list_avail < 0
&& __builtin_expect (robust != (void *) &pd->robust_head, 0))
{
do
{
struct __pthread_mutex_s *this = (struct __pthread_mutex_s *)
((char *) robust - offsetof (struct __pthread_mutex_s,
__list.__next));
robust = *((void **) robust);
# if __PTHREAD_MUTEX_HAVE_PREV
this->__list.__prev = NULL;
# endif
this->__list.__next = NULL;
atomic_or (&this->__lock, FUTEX_OWNER_DIED);
futex_wake ((unsigned int *) &this->__lock, 1,
/* XYZ */ FUTEX_SHARED);
}
while (robust != (void *) &pd->robust_head);
}
#endif
advise_stack_range (pd->stackblock, pd->stackblock_size, (uintptr_t) pd,
pd->guardsize);
/* If the thread is detached free the TCB. */
if (IS_DETACHED (pd))
/* Free the TCB. */
__free_tcb (pd);
else if (__glibc_unlikely (pd->cancelhandling & SETXID_BITMASK))
{
/* Some other thread might call any of the setXid functions and expect
us to reply. In this case wait until we did that. */
do
/* XXX This differs from the typical futex_wait_simple pattern in that
the futex_wait condition (setxid_futex) is different from the
condition used in the surrounding loop (cancelhandling). We need
to check and document why this is correct. */
futex_wait_simple (&pd->setxid_futex, 0, FUTEX_PRIVATE);
while (pd->cancelhandling & SETXID_BITMASK);
/* Reset the value so that the stack can be reused. */
pd->setxid_futex = 0;
}
/* We cannot call '_exit' here. '_exit' will terminate the process.
The 'exit' implementation in the kernel will signal when the
process is really dead since 'clone' got passed the CLONE_CHILD_CLEARTID
flag. The 'tid' field in the TCB will be set to zero.
The exit code is zero since in case all threads exit by calling
'pthread_exit' the exit status must be 0 (zero). */
__exit_thread ();
/* NOTREACHED */
}
/* Return true iff obliged to report TD_CREATE events. */
static bool
report_thread_creation (struct pthread *pd)
{
if (__glibc_unlikely (THREAD_GETMEM (THREAD_SELF, report_events)))
{
/* The parent thread is supposed to report events.
Check whether the TD_CREATE event is needed, too. */
const size_t idx = __td_eventword (TD_CREATE);
const uint32_t mask = __td_eventmask (TD_CREATE);
return ((mask & (__nptl_threads_events.event_bits[idx]
| pd->eventbuf.eventmask.event_bits[idx])) != 0);
}
return false;
}
int
__pthread_create_2_1 (pthread_t *newthread, const pthread_attr_t *attr,
void *(*start_routine) (void *), void *arg)
{
STACK_VARIABLES;
const struct pthread_attr *iattr = (struct pthread_attr *) attr;
struct pthread_attr default_attr;
bool free_cpuset = false;
bool c11 = (attr == ATTR_C11_THREAD);
if (iattr == NULL || c11)
{
lll_lock (__default_pthread_attr_lock, LLL_PRIVATE);
default_attr = __default_pthread_attr;
size_t cpusetsize = default_attr.cpusetsize;
if (cpusetsize > 0)
{
cpu_set_t *cpuset;
if (__glibc_likely (__libc_use_alloca (cpusetsize)))
cpuset = __alloca (cpusetsize);
else
{
cpuset = malloc (cpusetsize);
if (cpuset == NULL)
{
lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
return ENOMEM;
}
free_cpuset = true;
}
memcpy (cpuset, default_attr.cpuset, cpusetsize);
default_attr.cpuset = cpuset;
}
lll_unlock (__default_pthread_attr_lock, LLL_PRIVATE);
iattr = &default_attr;
}
struct pthread *pd = NULL;
int err = ALLOCATE_STACK (iattr, &pd);
int retval = 0;
if (__glibc_unlikely (err != 0))
/* Something went wrong. Maybe a parameter of the attributes is
invalid or we could not allocate memory. Note we have to
translate error codes. */
{
retval = err == ENOMEM ? EAGAIN : err;
goto out;
}
/* Initialize the TCB. All initializations with zero should be
performed in 'get_cached_stack'. This way we avoid doing this if
the stack freshly allocated with 'mmap'. */
#if TLS_TCB_AT_TP
/* Reference to the TCB itself. */
pd->header.self = pd;
/* Self-reference for TLS. */
pd->header.tcb = pd;
#endif
/* Store the address of the start routine and the parameter. Since
we do not start the function directly the stillborn thread will
get the information from its thread descriptor. */
pd->start_routine = start_routine;
pd->arg = arg;
pd->c11 = c11;
/* Copy the thread attribute flags. */
struct pthread *self = THREAD_SELF;
pd->flags = ((iattr->flags & ~(ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET))
| (self->flags & (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET)));
/* Initialize the field for the ID of the thread which is waiting
for us. This is a self-reference in case the thread is created
detached. */
pd->joinid = iattr->flags & ATTR_FLAG_DETACHSTATE ? pd : NULL;
/* The debug events are inherited from the parent. */
pd->eventbuf = self->eventbuf;
/* Copy the parent's scheduling parameters. The flags will say what
is valid and what is not. */
pd->schedpolicy = self->schedpolicy;
pd->schedparam = self->schedparam;
/* Copy the stack guard canary. */
#ifdef THREAD_COPY_STACK_GUARD
THREAD_COPY_STACK_GUARD (pd);
#endif
/* Copy the pointer guard value. */
#ifdef THREAD_COPY_POINTER_GUARD
THREAD_COPY_POINTER_GUARD (pd);
#endif
/* Setup tcbhead. */
tls_setup_tcbhead (pd);
/* Verify the sysinfo bits were copied in allocate_stack if needed. */
#ifdef NEED_DL_SYSINFO
CHECK_THREAD_SYSINFO (pd);
#endif
/* Inform start_thread (above) about cancellation state that might
translate into inherited signal state. */
pd->parent_cancelhandling = THREAD_GETMEM (THREAD_SELF, cancelhandling);
/* Determine scheduling parameters for the thread. */
if (__builtin_expect ((iattr->flags & ATTR_FLAG_NOTINHERITSCHED) != 0, 0)
&& (iattr->flags & (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET)) != 0)
{
/* Use the scheduling parameters the user provided. */
if (iattr->flags & ATTR_FLAG_POLICY_SET)
{
pd->schedpolicy = iattr->schedpolicy;
pd->flags |= ATTR_FLAG_POLICY_SET;
}
if (iattr->flags & ATTR_FLAG_SCHED_SET)
{
/* The values were validated in pthread_attr_setschedparam. */
pd->schedparam = iattr->schedparam;
pd->flags |= ATTR_FLAG_SCHED_SET;
}
if ((pd->flags & (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET))
!= (ATTR_FLAG_SCHED_SET | ATTR_FLAG_POLICY_SET))
collect_default_sched (pd);
}
if (__glibc_unlikely (__nptl_nthreads == 1))
_IO_enable_locks ();
/* Pass the descriptor to the caller. */
*newthread = (pthread_t) pd;
LIBC_PROBE (pthread_create, 4, newthread, attr, start_routine, arg);
/* One more thread. We cannot have the thread do this itself, since it
might exist but not have been scheduled yet by the time we've returned
and need to check the value to behave correctly. We must do it before
creating the thread, in case it does get scheduled first and then
might mistakenly think it was the only thread. In the failure case,
we momentarily store a false value; this doesn't matter because there
is no kosher thing a signal handler interrupting us right here can do
that cares whether the thread count is correct. */
atomic_increment (&__nptl_nthreads);
/* Our local value of stopped_start and thread_ran can be accessed at
any time. The PD->stopped_start may only be accessed if we have
ownership of PD (see CONCURRENCY NOTES above). */
bool stopped_start = false; bool thread_ran = false;
/* Start the thread. */
if (__glibc_unlikely (report_thread_creation (pd)))
{
stopped_start = true;
/* We always create the thread stopped at startup so we can
notify the debugger. */
retval = create_thread (pd, iattr, &stopped_start,
STACK_VARIABLES_ARGS, &thread_ran);
if (retval == 0)
{
/* We retain ownership of PD until (a) (see CONCURRENCY NOTES
above). */
/* Assert stopped_start is true in both our local copy and the
PD copy. */
assert (stopped_start);
assert (pd->stopped_start);
/* Now fill in the information about the new thread in
the newly created thread's data structure. We cannot let
the new thread do this since we don't know whether it was
already scheduled when we send the event. */
pd->eventbuf.eventnum = TD_CREATE;
pd->eventbuf.eventdata = pd;
/* Enqueue the descriptor. */
do
pd->nextevent = __nptl_last_event;
while (atomic_compare_and_exchange_bool_acq (&__nptl_last_event,
pd, pd->nextevent)
!= 0);
/* Now call the function which signals the event. See
CONCURRENCY NOTES for the nptl_db interface comments. */
__nptl_create_event ();
}
}
else
retval = create_thread (pd, iattr, &stopped_start,
STACK_VARIABLES_ARGS, &thread_ran);
if (__glibc_unlikely (retval != 0))
{
if (thread_ran)
/* State (c) or (d) and we may not have PD ownership (see
CONCURRENCY NOTES above). We can assert that STOPPED_START
must have been true because thread creation didn't fail, but
thread attribute setting did. */
/* See bug 19511 which explains why doing nothing here is a
resource leak for a joinable thread. */
assert (stopped_start);
else
{
/* State (e) and we have ownership of PD (see CONCURRENCY
NOTES above). */
/* Oops, we lied for a second. */
atomic_decrement (&__nptl_nthreads);
/* Perhaps a thread wants to change the IDs and is waiting for this
stillborn thread. */
if (__glibc_unlikely (atomic_exchange_acq (&pd->setxid_futex, 0)
== -2))
futex_wake (&pd->setxid_futex, 1, FUTEX_PRIVATE);
/* Free the resources. */
__deallocate_stack (pd);
}
/* We have to translate error codes. */
if (retval == ENOMEM)
retval = EAGAIN;
}
else
{
/* We don't know if we have PD ownership. Once we check the local
stopped_start we'll know if we're in state (a) or (b) (see
CONCURRENCY NOTES above). */
if (stopped_start)
/* State (a), we own PD. The thread blocked on this lock either
because we're doing TD_CREATE event reporting, or for some
other reason that create_thread chose. Now let it run
free. */
lll_unlock (pd->lock, LLL_PRIVATE);
/* We now have for sure more than one thread. The main thread might
not yet have the flag set. No need to set the global variable
again if this is what we use. */
THREAD_SETMEM (THREAD_SELF, header.multiple_threads, 1);
}
out:
if (__glibc_unlikely (free_cpuset))
free (default_attr.cpuset);
return retval;
}
versioned_symbol (libpthread, __pthread_create_2_1, pthread_create, GLIBC_2_1);
#if SHLIB_COMPAT(libpthread, GLIBC_2_0, GLIBC_2_1)
int
__pthread_create_2_0 (pthread_t *newthread, const pthread_attr_t *attr,
void *(*start_routine) (void *), void *arg)
{
/* The ATTR attribute is not really of type `pthread_attr_t *'. It has
the old size and access to the new members might crash the program.
We convert the struct now. */
struct pthread_attr new_attr;
if (attr != NULL)
{
struct pthread_attr *iattr = (struct pthread_attr *) attr;
size_t ps = __getpagesize ();
/* Copy values from the user-provided attributes. */
new_attr.schedparam = iattr->schedparam;
new_attr.schedpolicy = iattr->schedpolicy;
new_attr.flags = iattr->flags;
/* Fill in default values for the fields not present in the old
implementation. */
new_attr.guardsize = ps;
new_attr.stackaddr = NULL;
new_attr.stacksize = 0;
new_attr.cpuset = NULL;
/* We will pass this value on to the real implementation. */
attr = (pthread_attr_t *) &new_attr;
}
return __pthread_create_2_1 (newthread, attr, start_routine, arg);
}
compat_symbol (libpthread, __pthread_create_2_0, pthread_create,
GLIBC_2_0);
#endif
/* Information for libthread_db. */
#include "../nptl_db/db_info.c"
/* If pthread_create is present, libgcc_eh.a and libsupc++.a expects some other POSIX thread
functions to be present as well. */
PTHREAD_STATIC_FN_REQUIRE (__pthread_mutex_lock)
PTHREAD_STATIC_FN_REQUIRE (__pthread_mutex_trylock)
PTHREAD_STATIC_FN_REQUIRE (__pthread_mutex_unlock)
PTHREAD_STATIC_FN_REQUIRE (__pthread_once)
PTHREAD_STATIC_FN_REQUIRE (__pthread_cancel)
PTHREAD_STATIC_FN_REQUIRE (__pthread_key_create)
PTHREAD_STATIC_FN_REQUIRE (__pthread_key_delete)
PTHREAD_STATIC_FN_REQUIRE (__pthread_setspecific)
PTHREAD_STATIC_FN_REQUIRE (__pthread_getspecific)
|