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/* Thread creation.
Copyright (C) 2000-2020 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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
<https://www.gnu.org/licenses/>. */
#include <assert.h>
#include <errno.h>
#include <pthread.h>
#include <signal.h>
#include <resolv.h>
#include <atomic.h>
#include <hurd/resource.h>
#include <pt-internal.h>
#include <pthreadP.h>
#if IS_IN (libpthread)
# include <ctype.h>
#endif
#ifdef HAVE_USELOCALE
# include <locale.h>
#endif
/* The total number of pthreads currently active. This is defined
here since it would be really stupid to have a threads-using
program that doesn't call `pthread_create'. */
unsigned int __pthread_total;
/* The entry-point for new threads. */
static void
entry_point (struct __pthread *self, void *(*start_routine) (void *), void *arg)
{
___pthread_self = self;
__resp = &self->res_state;
#if IS_IN (libpthread)
/* Initialize pointers to locale data. */
__ctype_init ();
#endif
#ifdef HAVE_USELOCALE
/* A fresh thread needs to be bound to the global locale. */
uselocale (LC_GLOBAL_LOCALE);
#endif
__pthread_startup ();
__pthread_exit (start_routine (arg));
}
/* Create a thread with attributes given by ATTR, executing
START_ROUTINE with argument ARG. */
int
__pthread_create (pthread_t * thread, const pthread_attr_t * attr,
void *(*start_routine) (void *), void *arg)
{
int err;
struct __pthread *pthread;
err = __pthread_create_internal (&pthread, attr, start_routine, arg);
if (!err)
*thread = pthread->thread;
else if (err == ENOMEM)
err = EAGAIN;
return err;
}
strong_alias (__pthread_create, pthread_create)
/* Internal version of pthread_create. See comment in
pt-internal.h. */
int
__pthread_create_internal (struct __pthread **thread,
const pthread_attr_t * attr,
void *(*start_routine) (void *), void *arg)
{
int err;
struct __pthread *pthread;
const struct __pthread_attr *setup;
sigset_t sigset;
size_t stacksize;
/* Allocate a new thread structure. */
err = __pthread_alloc (&pthread);
if (err)
goto failed;
/* Use the default attributes if ATTR is NULL. */
setup = attr ? attr : &__pthread_default_attr;
stacksize = setup->__stacksize;
if (stacksize == 0)
{
struct rlimit rlim;
__getrlimit (RLIMIT_STACK, &rlim);
if (rlim.rlim_cur != RLIM_INFINITY)
stacksize = rlim.rlim_cur;
if (stacksize == 0)
stacksize = PTHREAD_STACK_DEFAULT;
}
/* Initialize the thread state. */
pthread->state = (setup->__detachstate == PTHREAD_CREATE_DETACHED
? PTHREAD_DETACHED : PTHREAD_JOINABLE);
if (setup->__stackaddr)
{
pthread->stackaddr = setup->__stackaddr;
/* If the user supplied a stack, it is not our responsibility to
setup a stack guard. */
pthread->guardsize = 0;
pthread->stack = 0;
}
else
{
/* Allocate a stack. */
err = __pthread_stack_alloc (&pthread->stackaddr,
((setup->__guardsize + __vm_page_size - 1)
/ __vm_page_size) * __vm_page_size
+ stacksize);
if (err)
goto failed_stack_alloc;
pthread->guardsize = setup->__guardsize;
pthread->stack = 1;
}
pthread->stacksize = stacksize;
/* Allocate the kernel thread and other required resources. */
err = __pthread_thread_alloc (pthread);
if (err)
goto failed_thread_alloc;
pthread->tcb = _dl_allocate_tls (NULL);
if (pthread->tcb == NULL)
{
err = ENOMEM;
goto failed_thread_tls_alloc;
}
pthread->tcb->tcb = pthread->tcb;
/* And initialize the rest of the machine context. This may include
additional machine- and system-specific initializations that
prove convenient. */
err = __pthread_setup (pthread, entry_point, start_routine, arg);
if (err)
goto failed_setup;
/* Initialize the system-specific signal state for the new
thread. */
err = __pthread_sigstate_init (pthread);
if (err)
goto failed_sigstate;
/* If the new thread is joinable, add a reference for the caller. */
if (pthread->state == PTHREAD_JOINABLE)
pthread->nr_refs++;
/* Set the new thread's signal mask and set the pending signals to
empty. POSIX says: "The signal mask shall be inherited from the
creating thread. The set of signals pending for the new thread
shall be empty." If the currnet thread is not a pthread then we
just inherit the process' sigmask. */
if (__pthread_num_threads == 1)
err = __sigprocmask (0, 0, &sigset);
else
err = __pthread_sigstate (_pthread_self (), 0, 0, &sigset, 0);
assert_perror (err);
err = __pthread_sigstate (pthread, SIG_SETMASK, &sigset, 0, 1);
assert_perror (err);
/* Increase the total number of threads. We do this before actually
starting the new thread, since the new thread might immediately
call `pthread_exit' which decreases the number of threads and
calls `exit' if the number of threads reaches zero. Increasing
the number of threads from within the new thread isn't an option
since this thread might return and call `pthread_exit' before the
new thread runs. */
atomic_increment (&__pthread_total);
/* Store a pointer to this thread in the thread ID lookup table. We
could use __thread_setid, however, we only lock for reading as no
other thread should be using this entry (we also assume that the
store is atomic). */
__pthread_rwlock_rdlock (&__pthread_threads_lock);
__pthread_threads[pthread->thread - 1] = pthread;
__pthread_rwlock_unlock (&__pthread_threads_lock);
/* At this point it is possible to guess our pthread ID. We have to
make sure that all functions taking a pthread_t argument can
handle the fact that this thread isn't really running yet. Since
the new thread might be passed its ID through pthread_create (to
avoid calling pthread_self), read it before starting the thread. */
*thread = pthread;
/* Schedule the new thread. */
err = __pthread_thread_start (pthread);
if (err)
goto failed_starting;
return 0;
failed_starting:
/* If joinable, a reference was added for the caller. */
if (pthread->state == PTHREAD_JOINABLE)
__pthread_dealloc (pthread);
__pthread_setid (pthread->thread, NULL);
atomic_decrement (&__pthread_total);
failed_sigstate:
__pthread_sigstate_destroy (pthread);
failed_setup:
_dl_deallocate_tls (pthread->tcb, 1);
pthread->tcb = NULL;
failed_thread_tls_alloc:
__pthread_thread_terminate (pthread);
/* __pthread_thread_terminate has taken care of deallocating the stack and
the thread structure. */
goto failed;
failed_thread_alloc:
if (pthread->stack)
__pthread_stack_dealloc (pthread->stackaddr,
((setup->__guardsize + __vm_page_size - 1)
/ __vm_page_size) * __vm_page_size + stacksize);
failed_stack_alloc:
__pthread_dealloc (pthread);
failed:
return err;
}
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