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NPTL: Conditionalize direct futex syscall uses.

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This commit is contained in:
Roland McGrath
2014-10-17 14:30:16 -07:00
parent 327ae25707
commit 184ee94010
7 changed files with 62 additions and 22 deletions
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36
nptl/pthread_mutex_init.c
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@ -18,6 +18,7 @@
#include <assert.h>
#include <errno.h>
#include <stdbool.h>
#include <string.h>
#include <kernel-features.h>
#include "pthreadP.h"
@ -31,10 +32,26 @@ static const struct pthread_mutexattr default_mutexattr =
};
#ifndef __ASSUME_FUTEX_LOCK_PI
static int tpi_supported;
static bool
prio_inherit_missing (void)
{
#ifdef __NR_futex
# ifndef __ASSUME_FUTEX_LOCK_PI
static int tpi_supported;
if (__glibc_unlikely (tpi_supported == 0))
{
int lock = 0;
INTERNAL_SYSCALL_DECL (err);
int ret = INTERNAL_SYSCALL (futex, err, 4, &lock, FUTEX_UNLOCK_PI, 0, 0);
assert (INTERNAL_SYSCALL_ERROR_P (ret, err));
tpi_supported = INTERNAL_SYSCALL_ERRNO (ret, err) == ENOSYS ? -1 : 1;
}
return __glibc_unlikely (tpi_supported < 0);
# endif
return false;
#endif
return true;
}
int
__pthread_mutex_init (mutex, mutexattr)
@ -58,19 +75,8 @@ __pthread_mutex_init (mutex, mutexattr)
break;
case PTHREAD_PRIO_INHERIT << PTHREAD_MUTEXATTR_PROTOCOL_SHIFT:
#ifndef __ASSUME_FUTEX_LOCK_PI
if (__glibc_unlikely (tpi_supported == 0))
{
int lock = 0;
INTERNAL_SYSCALL_DECL (err);
int ret = INTERNAL_SYSCALL (futex, err, 4, &lock, FUTEX_UNLOCK_PI,
0, 0);
assert (INTERNAL_SYSCALL_ERROR_P (ret, err));
tpi_supported = INTERNAL_SYSCALL_ERRNO (ret, err) == ENOSYS ? -1 : 1;
}
if (__glibc_unlikely (tpi_supported < 0))
if (__glibc_unlikely (prio_inherit_missing ()))
return ENOTSUP;
#endif
break;
default: