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/* Copyright (C) 2003-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003.
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 <endian.h>
#include <errno.h>
#include <sysdep.h>
#include <lowlevellock.h>
#include <pthread.h>
#include <pthreadP.h>
#include <kernel-features.h>
#include <shlib-compat.h>
#ifndef HAVE_CLOCK_GETTIME_VSYSCALL
# undef INTERNAL_VSYSCALL
# define INTERNAL_VSYSCALL INTERNAL_SYSCALL
# undef INLINE_VSYSCALL
# define INLINE_VSYSCALL INLINE_SYSCALL
#else
# include <bits/libc-vdso.h>
#endif
/* Cleanup handler, defined in pthread_cond_wait.c. */
extern void __condvar_cleanup (void *arg)
__attribute__ ((visibility ("hidden")));
struct _condvar_cleanup_buffer
{
int oldtype;
pthread_cond_t *cond;
pthread_mutex_t *mutex;
unsigned int bc_seq;
};
int
__pthread_cond_timedwait (cond, mutex, abstime)
pthread_cond_t *cond;
pthread_mutex_t *mutex;
const struct timespec *abstime;
{
struct _pthread_cleanup_buffer buffer;
struct _condvar_cleanup_buffer cbuffer;
int result = 0;
/* Catch invalid parameters. */
if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
return EINVAL;
int pshared = (cond->__data.__mutex == (void *) ~0l)
? LLL_SHARED : LLL_PRIVATE;
/* Make sure we are alone. */
lll_lock (cond->__data.__lock, pshared);
/* Now we can release the mutex. */
int err = __pthread_mutex_unlock_usercnt (mutex, 0);
if (err)
{
lll_unlock (cond->__data.__lock, pshared);
return err;
}
/* We have one new user of the condvar. */
++cond->__data.__total_seq;
++cond->__data.__futex;
cond->__data.__nwaiters += 1 << COND_NWAITERS_SHIFT;
/* Work around the fact that the kernel rejects negative timeout values
despite them being valid. */
if (__builtin_expect (abstime->tv_sec < 0, 0))
goto timeout;
/* Remember the mutex we are using here. If there is already a
different address store this is a bad user bug. Do not store
anything for pshared condvars. */
if (cond->__data.__mutex != (void *) ~0l)
cond->__data.__mutex = mutex;
/* Prepare structure passed to cancellation handler. */
cbuffer.cond = cond;
cbuffer.mutex = mutex;
/* Before we block we enable cancellation. Therefore we have to
install a cancellation handler. */
__pthread_cleanup_push (&buffer, __condvar_cleanup, &cbuffer);
/* The current values of the wakeup counter. The "woken" counter
must exceed this value. */
unsigned long long int val;
unsigned long long int seq;
val = seq = cond->__data.__wakeup_seq;
/* Remember the broadcast counter. */
cbuffer.bc_seq = cond->__data.__broadcast_seq;
while (1)
{
#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
|| !defined lll_futex_timed_wait_bitset)
struct timespec rt;
{
# ifdef __NR_clock_gettime
INTERNAL_SYSCALL_DECL (err);
int ret;
ret = INTERNAL_VSYSCALL (clock_gettime, err, 2,
(cond->__data.__nwaiters
& ((1 << COND_NWAITERS_SHIFT) - 1)),
&rt);
/* Convert the absolute timeout value to a relative timeout. */
rt.tv_sec = abstime->tv_sec - rt.tv_sec;
rt.tv_nsec = abstime->tv_nsec - rt.tv_nsec;
# else
/* Get the current time. So far we support only one clock. */
struct timeval tv;
(void) gettimeofday (&tv, NULL);
/* Convert the absolute timeout value to a relative timeout. */
rt.tv_sec = abstime->tv_sec - tv.tv_sec;
rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
# endif
}
if (rt.tv_nsec < 0)
{
rt.tv_nsec += 1000000000;
--rt.tv_sec;
}
/* Did we already time out? */
if (__builtin_expect (rt.tv_sec < 0, 0))
{
if (cbuffer.bc_seq != cond->__data.__broadcast_seq)
goto bc_out;
goto timeout;
}
#endif
unsigned int futex_val = cond->__data.__futex;
/* Prepare to wait. Release the condvar futex. */
lll_unlock (cond->__data.__lock, pshared);
/* Enable asynchronous cancellation. Required by the standard. */
cbuffer.oldtype = __pthread_enable_asynccancel ();
#if (!defined __ASSUME_FUTEX_CLOCK_REALTIME \
|| !defined lll_futex_timed_wait_bitset)
/* Wait until woken by signal or broadcast. */
err = lll_futex_timed_wait (&cond->__data.__futex,
futex_val, &rt, pshared);
#else
unsigned int clockbit = (cond->__data.__nwaiters & 1
? 0 : FUTEX_CLOCK_REALTIME);
err = lll_futex_timed_wait_bitset (&cond->__data.__futex, futex_val,
abstime, clockbit, pshared);
#endif
/* Disable asynchronous cancellation. */
__pthread_disable_asynccancel (cbuffer.oldtype);
/* We are going to look at shared data again, so get the lock. */
lll_lock (cond->__data.__lock, pshared);
/* If a broadcast happened, we are done. */
if (cbuffer.bc_seq != cond->__data.__broadcast_seq)
goto bc_out;
/* Check whether we are eligible for wakeup. */
val = cond->__data.__wakeup_seq;
if (val != seq && cond->__data.__woken_seq != val)
break;
/* Not woken yet. Maybe the time expired? */
if (__builtin_expect (err == -ETIMEDOUT, 0))
{
timeout:
/* Yep. Adjust the counters. */
++cond->__data.__wakeup_seq;
++cond->__data.__futex;
/* The error value. */
result = ETIMEDOUT;
break;
}
}
/* Another thread woken up. */
++cond->__data.__woken_seq;
bc_out:
cond->__data.__nwaiters -= 1 << COND_NWAITERS_SHIFT;
/* If pthread_cond_destroy was called on this variable already,
notify the pthread_cond_destroy caller all waiters have left
and it can be successfully destroyed. */
if (cond->__data.__total_seq == -1ULL
&& cond->__data.__nwaiters < (1 << COND_NWAITERS_SHIFT))
lll_futex_wake (&cond->__data.__nwaiters, 1, pshared);
/* We are done with the condvar. */
lll_unlock (cond->__data.__lock, pshared);
/* The cancellation handling is back to normal, remove the handler. */
__pthread_cleanup_pop (&buffer, 0);
/* Get the mutex before returning. */
err = __pthread_mutex_cond_lock (mutex);
return err ?: result;
}
versioned_symbol (libpthread, __pthread_cond_timedwait, pthread_cond_timedwait,
GLIBC_2_3_2);
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