glibc/htl/pt-create.c
Samuel Thibault 514638699d htl: Fix sigset of main thread
d482ebfa67 ('htl: Keep thread signals blocked during its initialization')
fixed not letting signals get delivered too early during thread creation,
but it also affected the main thread, thus making it block signals by
default.  We need to just let the main thread sigset as it is.
2021-09-26 02:40:26 +02:00

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8.5 KiB
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/* Thread creation.
Copyright (C) 2000-2021 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 <sys/single_threaded.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)
{
int err;
___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 ();
/* We can now unleash signals. */
err = __pthread_sigstate (self, SIG_SETMASK, &self->init_sigset, 0, 0);
assert_perror (err);
if (self->c11)
{
/* The function pointer of the c11 thread start is cast to an incorrect
type on __pthread_create 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*)) start_routine;
__pthread_exit ((void*) (uintptr_t) start (arg));
}
else
__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;
}
weak_alias (__pthread_create, pthread_create)
hidden_def (__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;
/* Avoid a data race in the multi-threaded case. */
if (__libc_single_threaded)
__libc_single_threaded = 0;
/* Allocate a new thread structure. */
err = __pthread_alloc (&pthread);
if (err)
goto failed;
if (attr == ATTR_C11_THREAD)
{
attr = NULL;
pthread->c11 = true;
}
else
pthread->c11 = false;
/* 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 (GL (dl_pthread_num_threads) == 1)
err = __sigprocmask (0, 0, &pthread->init_sigset);
else
err = __pthread_sigstate (_pthread_self (), 0, 0, &pthread->init_sigset, 0);
assert_perror (err);
if (start_routine)
/* But block the signals for now, until the thread is fully initialized. */
__sigfillset (&sigset);
else
sigset = pthread->init_sigset;
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). */
__libc_rwlock_rdlock (GL (dl_pthread_threads_lock));
GL (dl_pthread_threads)[pthread->thread - 1] = pthread;
__libc_rwlock_unlock (GL (dl_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;
}