69 lines
2.1 KiB
C
69 lines
2.1 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 <errno.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_setcancelstate (state, oldstate)
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int state;
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int *oldstate;
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{
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volatile struct pthread *self;
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if (state < PTHREAD_CANCEL_ENABLE || state > PTHREAD_CANCEL_DISABLE)
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return EINVAL;
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self = THREAD_SELF;
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while (1)
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{
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int oldval = THREAD_GETMEM (self, cancelhandling);
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int newval = (state == PTHREAD_CANCEL_DISABLE
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? oldval | CANCELSTATE_BITMASK
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: oldval & ~CANCELSTATE_BITMASK);
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/* Store the old value. */
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if (oldstate != NULL)
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*oldstate = ((oldval & CANCELSTATE_BITMASK)
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? PTHREAD_CANCEL_DISABLE : PTHREAD_CANCEL_ENABLE);
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/* Avoid doing unnecessary work. The atomic operation can
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potentially be expensive if the memory 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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/* Update the cancel handling word. 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 (&self->cancelhandling, newval,
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oldval) == 0)
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{
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if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval))
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__do_cancel ();
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break;
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}
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}
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return 0;
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}
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