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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>
63 lines
2.6 KiB
C
63 lines
2.6 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 <shlib-compat.h>
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#include "pthreadP.h"
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#include <stap-probe.h>
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#include <atomic.h>
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#include <futex-internal.h>
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#include "pthread_cond_common.c"
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/* See __pthread_cond_wait for a high-level description of the algorithm.
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A correct program must make sure that no waiters are blocked on the condvar
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when it is destroyed, and that there are no concurrent signals or
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broadcasts. To wake waiters reliably, the program must signal or
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broadcast while holding the mutex or after having held the mutex. It must
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also ensure that no signal or broadcast are still pending to unblock
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waiters; IOW, because waiters can wake up spuriously, the program must
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effectively ensure that destruction happens after the execution of those
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signal or broadcast calls.
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Thus, we can assume that all waiters that are still accessing the condvar
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have been woken. We wait until they have confirmed to have woken up by
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decrementing __wrefs. */
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int
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__pthread_cond_destroy (pthread_cond_t *cond)
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{
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LIBC_PROBE (cond_destroy, 1, cond);
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/* Set the wake request flag. We could also spin, but destruction that is
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concurrent with still-active waiters is probably neither common nor
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performance critical. Acquire MO to synchronize with waiters confirming
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that they finished. */
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unsigned int wrefs = atomic_fetch_or_acquire (&cond->__data.__wrefs, 4);
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int private = __condvar_get_private (wrefs);
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while (wrefs >> 3 != 0)
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{
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futex_wait_simple (&cond->__data.__wrefs, wrefs, private);
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/* See above. */
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wrefs = atomic_load_acquire (&cond->__data.__wrefs);
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}
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/* The memory the condvar occupies can now be reused. */
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return 0;
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}
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libc_hidden_def (__pthread_cond_destroy)
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versioned_symbol (libc, __pthread_cond_destroy,
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pthread_cond_destroy, GLIBC_2_3_2);
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