mirror of
https://sourceware.org/git/glibc.git
synced 2024-12-23 11:20:07 +00:00
9437b427ce
The bits tested to decide when to delay the return when switching off async cancel mode were wrong. Fix that. Also close a race condition in pthread_cancel where the bit indicating the cancellation is unconditionally set even if the cancel type might have changed.
130 lines
3.5 KiB
C
130 lines
3.5 KiB
C
/* Copyright (C) 2002, 2003, 2005, 2009 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 <setjmp.h>
|
|
#include <stdlib.h>
|
|
#include "pthreadP.h"
|
|
#include <atomic.h>
|
|
#include <bits/libc-lock.h>
|
|
|
|
|
|
#ifndef NOT_IN_libc
|
|
|
|
/* The next two functions are similar to pthread_setcanceltype() but
|
|
more specialized for the use in the cancelable functions like write().
|
|
They do not need to check parameters etc. */
|
|
int
|
|
attribute_hidden
|
|
__libc_enable_asynccancel (void)
|
|
{
|
|
struct pthread *self = THREAD_SELF;
|
|
int oldval = THREAD_GETMEM (self, cancelhandling);
|
|
|
|
while (1)
|
|
{
|
|
int newval = oldval | CANCELTYPE_BITMASK;
|
|
|
|
if (__builtin_expect ((oldval & CANCELED_BITMASK) != 0, 0))
|
|
{
|
|
/* If we are already exiting or if PTHREAD_CANCEL_DISABLED,
|
|
stop right here. */
|
|
if ((oldval & (EXITING_BITMASK | CANCELSTATE_BITMASK)) != 0)
|
|
break;
|
|
|
|
int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling,
|
|
newval, oldval);
|
|
if (__builtin_expect (curval != oldval, 0))
|
|
{
|
|
/* Somebody else modified the word, try again. */
|
|
oldval = curval;
|
|
continue;
|
|
}
|
|
|
|
THREAD_SETMEM (self, result, PTHREAD_CANCELED);
|
|
|
|
__do_cancel ();
|
|
|
|
/* NOTREACHED */
|
|
}
|
|
|
|
int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
|
|
oldval);
|
|
if (__builtin_expect (curval == oldval, 1))
|
|
break;
|
|
|
|
/* Prepare the next round. */
|
|
oldval = curval;
|
|
}
|
|
|
|
return oldval;
|
|
}
|
|
|
|
|
|
void
|
|
internal_function attribute_hidden
|
|
__libc_disable_asynccancel (int oldtype)
|
|
{
|
|
/* If asynchronous cancellation was enabled before we do not have
|
|
anything to do. */
|
|
if (oldtype & CANCELTYPE_BITMASK)
|
|
return;
|
|
|
|
struct pthread *self = THREAD_SELF;
|
|
int newval;
|
|
|
|
int oldval = THREAD_GETMEM (self, cancelhandling);
|
|
|
|
while (1)
|
|
{
|
|
newval = oldval & ~CANCELTYPE_BITMASK;
|
|
|
|
if (newval == oldval)
|
|
break;
|
|
|
|
int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
|
|
oldval);
|
|
if (__builtin_expect (curval == oldval, 1))
|
|
break;
|
|
|
|
/* Prepare the next round. */
|
|
oldval = curval;
|
|
}
|
|
|
|
/* We cannot return when we are being canceled. Upon return the
|
|
thread might be things which would have to be undone. The
|
|
following loop should loop until the cancellation signal is
|
|
delivered. */
|
|
while (__builtin_expect ((newval & (CANCELING_BITMASK | CANCELED_BITMASK))
|
|
== CANCELING_BITMASK, 0))
|
|
{
|
|
lll_futex_wait (&self->cancelhandling, newval, LLL_PRIVATE);
|
|
newval = THREAD_GETMEM (self, cancelhandling);
|
|
}
|
|
}
|
|
|
|
|
|
void
|
|
__libc_cleanup_routine (struct __pthread_cleanup_frame *f)
|
|
{
|
|
if (f->__do_it)
|
|
f->__cancel_routine (f->__cancel_arg);
|
|
}
|
|
|
|
#endif
|