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132 lines
3.7 KiB
C
132 lines
3.7 KiB
C
/* low level locking for pthread library. Generic futex-using version.
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Copyright (C) 2003-2014 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Paul Mackerras <paulus@au.ibm.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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<http://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <sysdep.h>
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#include <lowlevellock.h>
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#include <sys/time.h>
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#include <atomic.h>
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void
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__lll_lock_wait_private (int *futex)
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{
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if (*futex == 2)
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lll_futex_wait (futex, 2, LLL_PRIVATE); /* Wait if *futex == 2. */
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while (atomic_exchange_acq (futex, 2) != 0)
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lll_futex_wait (futex, 2, LLL_PRIVATE); /* Wait if *futex == 2. */
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}
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/* These functions don't get included in libc.so */
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#if IS_IN (libpthread)
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void
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__lll_lock_wait (int *futex, int private)
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{
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if (*futex == 2)
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lll_futex_wait (futex, 2, private); /* Wait if *futex == 2. */
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while (atomic_exchange_acq (futex, 2) != 0)
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lll_futex_wait (futex, 2, private); /* Wait if *futex == 2. */
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}
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int
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__lll_timedlock_wait (int *futex, const struct timespec *abstime, int private)
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{
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/* Reject invalid timeouts. */
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if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
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return EINVAL;
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/* Try locking. */
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while (atomic_exchange_acq (futex, 2) != 0)
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{
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struct timeval tv;
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/* Get the current time. */
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(void) __gettimeofday (&tv, NULL);
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/* Compute relative timeout. */
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struct timespec rt;
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rt.tv_sec = abstime->tv_sec - tv.tv_sec;
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rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
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if (rt.tv_nsec < 0)
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{
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rt.tv_nsec += 1000000000;
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--rt.tv_sec;
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}
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if (rt.tv_sec < 0)
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return ETIMEDOUT;
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/* If *futex == 2, wait until woken or timeout. */
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lll_futex_timed_wait (futex, 2, &rt, private);
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}
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return 0;
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}
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/* The kernel notifies a process which uses CLONE_CHILD_CLEARTID via futex
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wake-up when the clone terminates. The memory location contains the
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thread ID while the clone is running and is reset to zero by the kernel
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afterwards. The kernel up to version 3.16.3 does not use the private futex
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operations for futex wake-up when the clone terminates. */
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int
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__lll_timedwait_tid (int *tidp, const struct timespec *abstime)
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{
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int tid;
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if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
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return EINVAL;
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/* Repeat until thread terminated. */
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while ((tid = *tidp) != 0)
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{
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struct timeval tv;
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struct timespec rt;
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/* Get the current time. */
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(void) __gettimeofday (&tv, NULL);
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/* Compute relative timeout. */
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rt.tv_sec = abstime->tv_sec - tv.tv_sec;
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rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000;
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if (rt.tv_nsec < 0)
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{
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rt.tv_nsec += 1000000000;
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--rt.tv_sec;
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}
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/* Already timed out? */
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if (rt.tv_sec < 0)
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return ETIMEDOUT;
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/* If *tidp == tid, wait until thread terminates or the wait times out.
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The kernel up to version 3.16.3 does not use the private futex
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operations for futex wake-up when the clone terminates.
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*/
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if (lll_futex_timed_wait (tidp, tid, &rt, LLL_SHARED) == -ETIMEDOUT)
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return ETIMEDOUT;
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}
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return 0;
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}
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#endif
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