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When disabling async cancellation we cannot return from the function call if the thread is canceled. This happens when the cancel bits have been set before async cancel is disabled but the signal hasn't been sent/received yet. Delay for as long as necessary since otherwise the signal might be received in an unsafe context.
134 lines
3.6 KiB
C
134 lines
3.6 KiB
C
/* Copyright (C) 2002, 2003, 2005, 2009 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 <setjmp.h>
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#include <stdlib.h>
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#include "pthreadP.h"
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#include <atomic.h>
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#include <bits/libc-lock.h>
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#ifndef NOT_IN_libc
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/* The next two functions are similar to pthread_setcanceltype() but
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more specialized for the use in the cancelable functions like write().
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They do not need to check parameters etc. */
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int
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attribute_hidden
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__libc_enable_asynccancel (void)
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{
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struct pthread *self = THREAD_SELF;
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int oldval = THREAD_GETMEM (self, cancelhandling);
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while (1)
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{
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int newval = oldval | CANCELTYPE_BITMASK;
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if (__builtin_expect ((oldval & CANCELED_BITMASK) != 0, 0))
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{
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/* If we are already exiting or if PTHREAD_CANCEL_DISABLED,
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stop right here. */
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if ((oldval & (EXITING_BITMASK | CANCELSTATE_BITMASK)) != 0)
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break;
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int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
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newval, oldval);
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if (__builtin_expect (curval != oldval, 0))
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{
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/* Somebody else modified the word, try again. */
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oldval = curval;
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continue;
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}
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THREAD_SETMEM (self, result, PTHREAD_CANCELED);
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__do_cancel ();
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/* NOTREACHED */
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}
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int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
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oldval);
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if (__builtin_expect (curval == oldval, 1))
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break;
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/* Prepare the next round. */
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oldval = curval;
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}
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return oldval;
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}
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void
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internal_function attribute_hidden
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__libc_disable_asynccancel (int oldtype)
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{
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/* If asynchronous cancellation was enabled before we do not have
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anything to do. */
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if (oldtype & CANCELTYPE_BITMASK)
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return;
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struct pthread *self = THREAD_SELF;
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int newval;
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#ifdef THREAD_ATOMIC_AND
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THREAD_ATOMIC_AND (self, cancelhandling, ~CANCELTYPE_BITMASK);
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newval = THREAD_GETMEM (self, cancelhandling);
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#else
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int oldval = THREAD_GETMEM (self, cancelhandling);
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while (1)
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{
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newval = oldval & ~CANCELTYPE_BITMASK;
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if (newval == oldval)
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break;
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int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
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oldval);
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if (__builtin_expect (curval == oldval, 1))
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break;
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/* Prepare the next round. */
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oldval = curval;
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}
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#endif
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/* We cannot return when we are being canceled. Upon return the
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thread might be things which would have to be undone. The
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following loop should loop until the cancellation signal is
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delivered. */
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while (__builtin_expect (newval & CANCELED_BITMASK, 0))
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{
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lll_futex_wait (&self->cancelhandling, newval, LLL_PRIVATE);
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newval = THREAD_GETMEM (self, cancelhandling);
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}
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}
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void
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__libc_cleanup_routine (struct __pthread_cleanup_frame *f)
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{
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if (f->__do_it)
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f->__cancel_routine (f->__cancel_arg);
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}
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#endif
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