63 lines
1.9 KiB
C
63 lines
1.9 KiB
C
/* Copyright (C) 2002 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
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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, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <signal.h>
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#include "pthreadP.h"
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#include "atomic.h"
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int
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pthread_cancel (th)
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pthread_t th;
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{
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volatile struct pthread *pd = (volatile struct pthread *) th;
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while (1)
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{
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int oldval = pd->cancelhandling;
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int newval = oldval | CANCELED_BITMASK;
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/* Avoid doing unnecessary work. The atomic operation can
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potentially be expensive if the bug has to be locked and
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remote cache lines have to be invalidated. */
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if (oldval == newval)
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break;
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/* If the cancellation is handled asynchronously just send a
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signal. We avoid this if possible since it's more
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expensive. */
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if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval))
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{
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/* The cancellation handler will take care of marking the
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thread as canceled. */
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__pthread_kill (th, SIGCANCEL);
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break;
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}
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/* Mark the thread as canceled. This has to be done
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atomically since other bits could be modified as well. */
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if (atomic_compare_and_exchange_acq (&pd->cancelhandling, newval,
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oldval) == 0)
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break;
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}
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return 0;
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}
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