mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-05 03:01:05 +00:00
3d008a92a8
'sem' is the opaque 'sem_t', 'isem' is the actual 'struct new_sem'. Signed-off-by: Sergey Bugaev <bugaevc@gmail.com> Message-Id: <20230212111044.610942-6-bugaevc@gmail.com>
208 lines
5.0 KiB
C
208 lines
5.0 KiB
C
/* Wait on a semaphore with a timeout. Generic version.
|
|
Copyright (C) 2005-2023 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 <semaphore.h>
|
|
#include <errno.h>
|
|
#include <assert.h>
|
|
#include <time.h>
|
|
#include <hurdlock.h>
|
|
#include <hurd/hurd.h>
|
|
#include <sysdep-cancel.h>
|
|
|
|
#include <pt-internal.h>
|
|
|
|
#if !__HAVE_64B_ATOMICS
|
|
static void
|
|
__sem_wait_32_finish (struct new_sem *isem);
|
|
#endif
|
|
|
|
static void
|
|
__sem_wait_cleanup (void *arg)
|
|
{
|
|
struct new_sem *isem = arg;
|
|
|
|
#if __HAVE_64B_ATOMICS
|
|
atomic_fetch_add_relaxed (&isem->data, -((uint64_t) 1 << SEM_NWAITERS_SHIFT));
|
|
#else
|
|
__sem_wait_32_finish (isem);
|
|
#endif
|
|
}
|
|
|
|
int
|
|
__sem_timedwait_internal (sem_t *restrict sem,
|
|
clockid_t clock_id,
|
|
const struct timespec *restrict timeout)
|
|
{
|
|
struct new_sem *isem = (struct new_sem *) sem;
|
|
int err, ret = 0;
|
|
int flags = isem->pshared ? GSYNC_SHARED : 0;
|
|
|
|
__pthread_testcancel ();
|
|
|
|
if (__sem_waitfast (isem, 0) == 0)
|
|
return 0;
|
|
|
|
int cancel_oldtype = LIBC_CANCEL_ASYNC();
|
|
|
|
#if __HAVE_64B_ATOMICS
|
|
uint64_t d = atomic_fetch_add_relaxed (&isem->data,
|
|
(uint64_t) 1 << SEM_NWAITERS_SHIFT);
|
|
|
|
pthread_cleanup_push (__sem_wait_cleanup, isem);
|
|
|
|
for (;;)
|
|
{
|
|
if ((d & SEM_VALUE_MASK) == 0)
|
|
{
|
|
/* No token, sleep. */
|
|
if (timeout)
|
|
err = __lll_abstimed_wait_intr (
|
|
((unsigned int *) &isem->data) + SEM_VALUE_OFFSET,
|
|
0, timeout, flags, clock_id);
|
|
else
|
|
err = __lll_wait_intr (
|
|
((unsigned int *) &isem->data) + SEM_VALUE_OFFSET,
|
|
0, flags);
|
|
|
|
if (err != 0 && err != KERN_INVALID_ARGUMENT)
|
|
{
|
|
/* Error, interruption or timeout, abort. */
|
|
if (err == KERN_TIMEDOUT)
|
|
err = ETIMEDOUT;
|
|
if (err == KERN_INTERRUPTED)
|
|
err = EINTR;
|
|
ret = __hurd_fail (err);
|
|
__sem_wait_cleanup (isem);
|
|
break;
|
|
}
|
|
|
|
/* Token changed */
|
|
d = atomic_load_relaxed (&isem->data);
|
|
}
|
|
else
|
|
{
|
|
/* Try to acquire and dequeue. */
|
|
if (atomic_compare_exchange_weak_acquire (&isem->data,
|
|
&d, d - 1 - ((uint64_t) 1 << SEM_NWAITERS_SHIFT)))
|
|
{
|
|
/* Success */
|
|
ret = 0;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
pthread_cleanup_pop (0);
|
|
#else
|
|
unsigned int v;
|
|
|
|
atomic_fetch_add_acquire (&isem->nwaiters, 1);
|
|
|
|
pthread_cleanup_push (__sem_wait_cleanup, isem);
|
|
|
|
v = atomic_load_relaxed (&isem->value);
|
|
do
|
|
{
|
|
do
|
|
{
|
|
do
|
|
{
|
|
if ((v & SEM_NWAITERS_MASK) != 0)
|
|
break;
|
|
}
|
|
while (!atomic_compare_exchange_weak_release (&isem->value,
|
|
&v, v | SEM_NWAITERS_MASK));
|
|
|
|
if ((v >> SEM_VALUE_SHIFT) == 0)
|
|
{
|
|
/* No token, sleep. */
|
|
if (timeout)
|
|
err = __lll_abstimed_wait_intr (&isem->value,
|
|
SEM_NWAITERS_MASK, timeout, flags, clock_id);
|
|
else
|
|
err = __lll_wait_intr (&isem->value,
|
|
SEM_NWAITERS_MASK, flags);
|
|
|
|
if (err != 0 && err != KERN_INVALID_ARGUMENT)
|
|
{
|
|
/* Error, interruption or timeout, abort. */
|
|
if (err == KERN_TIMEDOUT)
|
|
err = ETIMEDOUT;
|
|
if (err == KERN_INTERRUPTED)
|
|
err = EINTR;
|
|
ret = __hurd_fail (err);
|
|
goto error;
|
|
}
|
|
|
|
/* Token changed */
|
|
v = atomic_load_relaxed (&isem->value);
|
|
}
|
|
}
|
|
while ((v >> SEM_VALUE_SHIFT) == 0);
|
|
}
|
|
while (!atomic_compare_exchange_weak_acquire (&isem->value,
|
|
&v, v - (1 << SEM_VALUE_SHIFT)));
|
|
|
|
error:
|
|
pthread_cleanup_pop (0);
|
|
|
|
__sem_wait_32_finish (isem);
|
|
#endif
|
|
|
|
LIBC_CANCEL_RESET (cancel_oldtype);
|
|
|
|
return ret;
|
|
}
|
|
|
|
#if !__HAVE_64B_ATOMICS
|
|
/* Stop being a registered waiter (non-64b-atomics code only). */
|
|
static void
|
|
__sem_wait_32_finish (struct new_sem *isem)
|
|
{
|
|
unsigned int wguess = atomic_load_relaxed (&isem->nwaiters);
|
|
if (wguess == 1)
|
|
atomic_fetch_and_acquire (&isem->value, ~SEM_NWAITERS_MASK);
|
|
|
|
unsigned int wfinal = atomic_fetch_add_release (&isem->nwaiters, -1);
|
|
if (wfinal > 1 && wguess == 1)
|
|
{
|
|
unsigned int v = atomic_fetch_or_relaxed (&isem->value,
|
|
SEM_NWAITERS_MASK);
|
|
v >>= SEM_VALUE_SHIFT;
|
|
while (v--)
|
|
__lll_wake (&isem->value, isem->pshared ? GSYNC_SHARED : 0);
|
|
}
|
|
}
|
|
#endif
|
|
|
|
int
|
|
__sem_clockwait (sem_t *sem, clockid_t clockid,
|
|
const struct timespec *restrict timeout)
|
|
{
|
|
return __sem_timedwait_internal (sem, clockid, timeout);
|
|
}
|
|
weak_alias (__sem_clockwait, sem_clockwait);
|
|
|
|
int
|
|
__sem_timedwait (sem_t *restrict sem, const struct timespec *restrict timeout)
|
|
{
|
|
return __sem_timedwait_internal (sem, CLOCK_REALTIME, timeout);
|
|
}
|
|
|
|
weak_alias (__sem_timedwait, sem_timedwait);
|