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glibc/nptl/lowlevelrobustlock.c
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/* Copyright (C) 2006-2016 Free Software Foundation, Inc. | |
This file is part of the GNU C Library. | |
Contributed by Jakub Jelinek <jakub@redhat.com>, 2006. | |
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 <errno.h> | |
#include <sysdep.h> | |
#include <lowlevellock.h> | |
#include <sys/time.h> | |
#include <pthreadP.h> | |
#include <kernel-features.h> | |
int | |
__lll_robust_lock_wait (int *futex, int private) | |
{ | |
int oldval = *futex; | |
int tid = THREAD_GETMEM (THREAD_SELF, tid); | |
/* If the futex changed meanwhile try locking again. */ | |
if (oldval == 0) | |
goto try; | |
do | |
{ | |
/* If the owner died, return the present value of the futex. */ | |
if (__glibc_unlikely (oldval & FUTEX_OWNER_DIED)) | |
return oldval; | |
/* Try to put the lock into state 'acquired, possibly with waiters'. */ | |
int newval = oldval | FUTEX_WAITERS; | |
if (oldval != newval | |
&& atomic_compare_and_exchange_bool_acq (futex, newval, oldval)) | |
continue; | |
/* If *futex == 2, wait until woken. */ | |
lll_futex_wait (futex, newval, private); | |
try: | |
; | |
} | |
while ((oldval = atomic_compare_and_exchange_val_acq (futex, | |
tid | FUTEX_WAITERS, | |
0)) != 0); | |
return 0; | |
} | |
int | |
__lll_robust_timedlock_wait (int *futex, const struct timespec *abstime, | |
int private) | |
{ | |
/* Reject invalid timeouts. */ | |
if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000) | |
return EINVAL; | |
int tid = THREAD_GETMEM (THREAD_SELF, tid); | |
int oldval = *futex; | |
/* If the futex changed meanwhile, try locking again. */ | |
if (oldval == 0) | |
goto try; | |
/* Work around the fact that the kernel rejects negative timeout values | |
despite them being valid. */ | |
if (__glibc_unlikely (abstime->tv_sec < 0)) | |
return ETIMEDOUT; | |
do | |
{ | |
#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \ | |
|| !defined lll_futex_timed_wait_bitset) | |
struct timeval tv; | |
struct timespec rt; | |
/* Get the current time. */ | |
(void) __gettimeofday (&tv, NULL); | |
/* Compute relative timeout. */ | |
rt.tv_sec = abstime->tv_sec - tv.tv_sec; | |
rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000; | |
if (rt.tv_nsec < 0) | |
{ | |
rt.tv_nsec += 1000000000; | |
--rt.tv_sec; | |
} | |
/* Already timed out? */ | |
if (rt.tv_sec < 0) | |
return ETIMEDOUT; | |
#endif | |
/* If the owner died, return the present value of the futex. */ | |
if (__glibc_unlikely (oldval & FUTEX_OWNER_DIED)) | |
return oldval; | |
/* Try to put the lock into state 'acquired, possibly with waiters'. */ | |
int newval = oldval | FUTEX_WAITERS; | |
if (oldval != newval | |
&& atomic_compare_and_exchange_bool_acq (futex, newval, oldval)) | |
continue; | |
/* If *futex == 2, wait until woken or timeout. */ | |
#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \ | |
|| !defined lll_futex_timed_wait_bitset) | |
lll_futex_timed_wait (futex, newval, &rt, private); | |
#else | |
lll_futex_timed_wait_bitset (futex, newval, abstime, | |
FUTEX_CLOCK_REALTIME, private); | |
#endif | |
try: | |
; | |
} | |
while ((oldval = atomic_compare_and_exchange_val_acq (futex, | |
tid | FUTEX_WAITERS, | |
0)) != 0); | |
return 0; | |
} |