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/* Copyright (C) 2002, 2003 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <signal.h>
#include "pthreadP.h"
#include "atomic.h"
int
pthread_cancel (th)
pthread_t th;
{
volatile struct pthread *pd = (volatile struct pthread *) th;
int result = 0;
while (1)
{
int oldval = pd->cancelhandling;
int newval = oldval | CANCELING_BITMASK | CANCELED_BITMASK;
/* Avoid doing unnecessary work. The atomic operation can
potentially be expensive if the bug has to be locked and
remote cache lines have to be invalidated. */
if (oldval == newval)
break;
/* If the cancellation is handled asynchronously just send a
signal. We avoid this if possible since it's more
expensive. */
if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval))
{
/* Mark the cancellation as "in progress". */
atomic_bit_set (&pd->cancelhandling, CANCELING_BIT);
/* The cancellation handler will take care of marking the
thread as canceled. */
result = __pthread_kill (th, SIGCANCEL);
break;
}
/* Mark the thread as canceled. This has to be done
atomically since other bits could be modified as well. */
if (atomic_compare_and_exchange_acq (&pd->cancelhandling, newval,
oldval) == 0)
break;
}
return result;
}
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