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nptl: Export __libc_multiple_threads from libc as an internal symbol

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This allows the elimination of the __libc_multiple_threads_ptr
variable in libpthread and its initialization procedure.

Tested-by: Carlos O'Donell <carlos@redhat.com>
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
This commit is contained in:
Florian Weimer 2021-05-10 10:31:41 +02:00
parent d6163dfd38
commit 321789f61a
8 changed files with 13 additions and 30 deletions
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1
nptl/Versions
View File

@ -305,6 +305,7 @@ libc {
__libc_cleanup_pop_restore;
__libc_cleanup_push_defer;
__libc_dl_error_tsd;
__libc_multiple_threads;
__libc_pthread_init;
__lll_clocklock_elision;
__lll_lock_elision;

4
nptl/allocatestack.c
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@ -477,7 +477,7 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
/* This is at least the second thread. */
pd->header.multiple_threads = 1;
#ifndef TLS_MULTIPLE_THREADS_IN_TCB
__pthread_multiple_threads = *__libc_multiple_threads_ptr = 1;
__pthread_multiple_threads = __libc_multiple_threads = 1;
#endif
#ifdef NEED_DL_SYSINFO
@ -598,7 +598,7 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
/* This is at least the second thread. */
pd->header.multiple_threads = 1;
#ifndef TLS_MULTIPLE_THREADS_IN_TCB
__pthread_multiple_threads = *__libc_multiple_threads_ptr = 1;
__pthread_multiple_threads = __libc_multiple_threads = 1;
#endif
#ifdef NEED_DL_SYSINFO

3
nptl/libc_multiple_threads.c
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@ -23,6 +23,7 @@
/* Variable set to a nonzero value either if more than one thread runs or ran,
or if a single-threaded process is trying to cancel itself. See
nptl/descr.h for more context on the single-threaded process case. */
int __libc_multiple_threads attribute_hidden;
int __libc_multiple_threads __attribute__ ((nocommon));
libc_hidden_data_def (__libc_multiple_threads)
# endif
#endif

11
nptl/libc_pthread_init.c
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@ -27,20 +27,9 @@
#include <sysdep.h>
#include <ldsodefs.h>
#ifdef TLS_MULTIPLE_THREADS_IN_TCB
void
#else
extern int __libc_multiple_threads attribute_hidden;
int *
#endif
__libc_pthread_init (void (*reclaim) (void))
{
/* Called by a child after fork. */
__register_atfork (NULL, NULL, reclaim, NULL);
#ifndef TLS_MULTIPLE_THREADS_IN_TCB
return &__libc_multiple_threads;
#endif
}

10
nptl/nptl-init.c
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@ -37,11 +37,6 @@
#include <libc-pointer-arith.h>
#include <pthread_mutex_conf.h>
#ifndef TLS_MULTIPLE_THREADS_IN_TCB
/* Pointer to the corresponding variable in libc. */
int *__libc_multiple_threads_ptr attribute_hidden;
#endif
/* Size and alignment of static TLS block. */
size_t __static_tls_size;
size_t __static_tls_align_m1;
@ -183,10 +178,7 @@ __pthread_initialize_minimal_internal (void)
#endif
/* Register the fork generation counter with the libc. */
#ifndef TLS_MULTIPLE_THREADS_IN_TCB
__libc_multiple_threads_ptr =
#endif
__libc_pthread_init (__reclaim_stacks);
__libc_pthread_init (__reclaim_stacks);
}
strong_alias (__pthread_initialize_minimal_internal,
__pthread_initialize_minimal)

6
nptl/pthreadP.h
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@ -368,17 +368,13 @@ extern unsigned long int __fork_generation attribute_hidden;
extern unsigned long int *__fork_generation_pointer attribute_hidden;
/* Register the generation counter in the libpthread with the libc. */
#ifdef TLS_MULTIPLE_THREADS_IN_TCB
extern void __libc_pthread_init (void (*reclaim) (void));
#else
extern int *__libc_pthread_init (void (*reclaim) (void));
#ifndef TLS_MULTIPLE_THREADS_IN_TCB
/* Variable set to a nonzero value either if more than one thread runs or ran,
or if a single-threaded process is trying to cancel itself. See
nptl/descr.h for more context on the single-threaded process case. */
extern int __pthread_multiple_threads attribute_hidden;
/* Pointer to the corresponding variable in libc. */
extern int *__libc_multiple_threads_ptr attribute_hidden;
#endif
extern size_t __pthread_get_minstack (const pthread_attr_t *attr);

2
nptl/pthread_cancel.c
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@ -90,7 +90,7 @@ __pthread_cancel (pthread_t th)
points get executed. */
THREAD_SETMEM (THREAD_SELF, header.multiple_threads, 1);
#ifndef TLS_MULTIPLE_THREADS_IN_TCB
__pthread_multiple_threads = *__libc_multiple_threads_ptr = 1;
__pthread_multiple_threads = __libc_multiple_threads = 1;
#endif
}
/* Mark the thread as canceled. This has to be done

6
sysdeps/unix/sysv/linux/single-thread.h
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@ -27,9 +27,13 @@
The ABI might define SINGLE_THREAD_BY_GLOBAL to enable the single thread
check to use global variables instead of the pthread_t field. */
#ifndef __ASSEMBLER__
extern int __libc_multiple_threads;
libc_hidden_proto (__libc_multiple_threads)
#endif
#ifdef SINGLE_THREAD_BY_GLOBAL
# if IS_IN (libc)
extern int __libc_multiple_threads;
# define SINGLE_THREAD_P \
__glibc_likely (__libc_multiple_threads == 0)
# elif IS_IN (libpthread)