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215078017f
To help y2038 work avoid duplicate all the logic of nanosleep on
non cancellable version, the patch replace it with a new futex
operation, lll_timedwait. The changes are:
- Add a expected value for __lll_clocklock_wait, so it can be used
to wait for generic values.
- Remove its internal atomic operation and move the logic to
__lll_clocklock. It makes __lll_clocklock_wait even more generic
and __lll_clocklock slight faster on fast-path (since it won't
require a function call anymore).
- Add lll_timedwait, which uses __lll_clocklock_wait, to replace both
__pause_nocancel and __nanosleep_nocancel.
It also allows remove the sparc32 __lll_clocklock_wait implementation
(since it is similar to the generic one).
Checked on x86_64-linux-gnu, sparcv9-linux-gnu, and i686-linux-gnu.
Reviewed-by: Carlos O'Donell <carlos@redhat.com>
131 lines
3.8 KiB
C
131 lines
3.8 KiB
C
/* Copyright (C) 2003-2019 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Jakub Jelinek <jakub@redhat.com>, 2003.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef _LOWLEVELLOCK_H
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#define _LOWLEVELLOCK_H 1
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#include <time.h>
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#include <sys/param.h>
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#include <bits/pthreadtypes.h>
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#include <atomic.h>
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#include <kernel-features.h>
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#include <errno.h>
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#include <lowlevellock-futex.h>
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static inline int
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__attribute__ ((always_inline))
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__lll_trylock (int *futex)
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{
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return atomic_compare_and_exchange_val_24_acq (futex, 1, 0) != 0;
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}
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#define lll_trylock(futex) __lll_trylock (&(futex))
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static inline int
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__attribute__ ((always_inline))
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__lll_cond_trylock (int *futex)
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{
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return atomic_compare_and_exchange_val_24_acq (futex, 2, 0) != 0;
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}
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#define lll_cond_trylock(futex) __lll_cond_trylock (&(futex))
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extern void __lll_lock_wait_private (int *futex) attribute_hidden;
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extern void __lll_lock_wait (int *futex, int private) attribute_hidden;
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static inline void
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__attribute__ ((always_inline))
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__lll_lock (int *futex, int private)
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{
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int val = atomic_compare_and_exchange_val_24_acq (futex, 1, 0);
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if (__glibc_unlikely (val != 0))
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{
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if (__builtin_constant_p (private) && private == LLL_PRIVATE)
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__lll_lock_wait_private (futex);
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else
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__lll_lock_wait (futex, private);
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}
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}
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#define lll_lock(futex, private) __lll_lock (&(futex), private)
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static inline void
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__attribute__ ((always_inline))
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__lll_cond_lock (int *futex, int private)
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{
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int val = atomic_compare_and_exchange_val_24_acq (futex, 2, 0);
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if (__glibc_unlikely (val != 0))
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__lll_lock_wait (futex, private);
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}
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#define lll_cond_lock(futex, private) __lll_cond_lock (&(futex), private)
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extern int __lll_clocklock_wait (int *futex, clockid_t, int val,
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const struct timespec *,
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int private) attribute_hidden;
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#define lll_timedwait(futex, val, clockid, abstime, private) \
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__lll_clocklock_wait (futex, val, clockid, abstime, private)
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static inline int
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__attribute__ ((always_inline))
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__lll_clocklock (int *futex, clockid_t clockid,
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const struct timespec *abstime, int private)
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{
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int val = atomic_compare_and_exchange_val_24_acq (futex, 1, 0);
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int result = 0;
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if (__glibc_unlikely (val != 0))
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{
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do
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{
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int oldval = atomic_compare_and_exchange_val_24_acq (futex, val, 1);
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if (oldval != 0)
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{
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result = __lll_clocklock_wait (futex, 2, clockid, abstime,
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private);
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if (result == EINVAL || result == ETIMEDOUT)
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break;
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}
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}
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while (atomic_compare_and_exchange_val_24_acq (futex, val, 0) != 0);
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}
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return result;
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}
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#define lll_clocklock(futex, clockid, abstime, private) \
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__lll_clocklock (&(futex), clockid, abstime, private)
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#define lll_unlock(lock, private) \
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((void) ({ \
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int *__futex = &(lock); \
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int __private = (private); \
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int __val = atomic_exchange_24_rel (__futex, 0); \
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if (__glibc_unlikely (__val > 1)) \
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lll_futex_wake (__futex, 1, __private); \
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}))
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#define lll_islocked(futex) \
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(futex != 0)
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/* Initializers for lock. */
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#define LLL_LOCK_INITIALIZER (0)
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#define LLL_LOCK_INITIALIZER_LOCKED (1)
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#endif /* lowlevellock.h */
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