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30891f35fa
We stopped adding "Contributed by" or similar lines in sources in 2012 in favour of git logs and keeping the Contributors section of the glibc manual up to date. Removing these lines makes the license header a bit more consistent across files and also removes the possibility of error in attribution when license blocks or files are copied across since the contributed-by lines don't actually reflect reality in those cases. Move all "Contributed by" and similar lines (Written by, Test by, etc.) into a new file CONTRIBUTED-BY to retain record of these contributions. These contributors are also mentioned in manual/contrib.texi, so we just maintain this additional record as a courtesy to the earlier developers. The following scripts were used to filter a list of files to edit in place and to clean up the CONTRIBUTED-BY file respectively. These were not added to the glibc sources because they're not expected to be of any use in future given that this is a one time task: https://gist.github.com/siddhesh/b5ecac94eabfd72ed2916d6d8157e7dc https://gist.github.com/siddhesh/15ea1f5e435ace9774f485030695ee02 Reviewed-by: Carlos O'Donell <carlos@redhat.com>
68 lines
2.8 KiB
C
68 lines
2.8 KiB
C
/* Copyright (C) 2002-2021 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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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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#include <errno.h>
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#include "pthreadP.h"
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#include <atomic.h>
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#include <futex-internal.h>
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#include <shlib-compat.h>
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int
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__pthread_barrier_destroy (pthread_barrier_t *barrier)
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{
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struct pthread_barrier *bar = (struct pthread_barrier *) barrier;
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/* Destroying a barrier is only allowed if no thread is blocked on it.
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Thus, there is no unfinished round, and all modifications to IN will
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have happened before us (either because the calling thread took part
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in the most recent round and thus synchronized-with all other threads
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entering, or the program ensured this through other synchronization).
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We must wait until all threads that entered so far have confirmed that
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they have exited as well. To get the notification, pretend that we have
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reached the reset threshold. */
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unsigned int count = bar->count;
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unsigned int max_in_before_reset = BARRIER_IN_THRESHOLD
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- BARRIER_IN_THRESHOLD % count;
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/* Relaxed MO sufficient because the program must have ensured that all
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modifications happen-before this load (see above). */
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unsigned int in = atomic_load_relaxed (&bar->in);
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/* Trigger reset. The required acquire MO is below. */
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if (atomic_fetch_add_relaxed (&bar->out, max_in_before_reset - in) < in)
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{
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/* Not all threads confirmed yet that they have exited, so another
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thread will perform a reset. Wait until that has happened. */
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while (in != 0)
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{
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futex_wait_simple (&bar->in, in, bar->shared);
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in = atomic_load_relaxed (&bar->in);
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}
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}
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/* We must ensure that memory reuse happens after all prior use of the
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barrier (specifically, synchronize-with the reset of the barrier or the
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confirmation of threads leaving the barrier). */
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atomic_thread_fence_acquire ();
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return 0;
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}
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versioned_symbol (libc, __pthread_barrier_destroy, pthread_barrier_destroy,
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GLIBC_2_34);
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#if OTHER_SHLIB_COMPAT (libpthread, GLIBC_2_2, GLIBC_2_34)
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compat_symbol (libpthread, __pthread_barrier_destroy, pthread_barrier_destroy,
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GLIBC_2_2);
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#endif
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