Optimize for kernels which are known to have the vfork syscall.
[glibc/pb-stable.git] / nptl / pthread_setcancelstate.c
blob3f6ed863c38e4f107bb28a71eed15b521d4f41f0
1 /* Copyright (C) 2002 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, write to the Free
17 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
18 02111-1307 USA. */
20 #include <errno.h>
21 #include "pthreadP.h"
22 #include <atomic.h>
25 int
26 __pthread_setcancelstate (state, oldstate)
27 int state;
28 int *oldstate;
30 volatile struct pthread *self;
32 if (state < PTHREAD_CANCEL_ENABLE || state > PTHREAD_CANCEL_DISABLE)
33 return EINVAL;
35 self = THREAD_SELF;
37 while (1)
39 int oldval = THREAD_GETMEM (self, cancelhandling);
40 int newval = (state == PTHREAD_CANCEL_DISABLE
41 ? oldval | CANCELSTATE_BITMASK
42 : oldval & ~CANCELSTATE_BITMASK);
44 /* Store the old value. */
45 if (oldstate != NULL)
46 *oldstate = ((oldval & CANCELSTATE_BITMASK)
47 ? PTHREAD_CANCEL_DISABLE : PTHREAD_CANCEL_ENABLE);
49 /* Avoid doing unnecessary work. The atomic operation can
50 potentially be expensive if the memory has to be locked and
51 remote cache lines have to be invalidated. */
52 if (oldval == newval)
53 break;
55 /* Update the cancel handling word. This has to be done
56 atomically since other bits could be modified as well. */
57 if (atomic_compare_and_exchange_acq (&self->cancelhandling, newval,
58 oldval) == 0)
60 if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval))
61 __do_cancel ();
63 break;
67 return 0;
69 strong_alias (__pthread_setcancelstate, pthread_setcancelstate)