glibc/nptl/cancellation.c
Florian Weimer ce0b7961ae nptl: Consolidate async cancel enable/disable implementation in libc
Previously, the source file nptl/cancellation.c was compiled multiple
times, for libc, libpthread, librt.  This commit switches to a single
implementation, with new __pthread_enable_asynccancel@@GLIBC_PRIVATE,
__pthread_disable_asynccancel@@GLIBC_PRIVATE exports.

The almost-unused CANCEL_ASYNC and CANCEL_RESET macros are replaced
by LIBC_CANCEL_ASYNC and LIBC_CANCEL_ASYNC macros.  They call the
__pthread_* functions unconditionally now.  The macros are still
needed because shared code uses them; Hurd has different definitions.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>
2021-05-05 17:19:32 +02:00

105 lines
3.1 KiB
C

/* Copyright (C) 2002-2021 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, see
<https://www.gnu.org/licenses/>. */
#include <setjmp.h>
#include <stdlib.h>
#include "pthreadP.h"
#include <futex-internal.h>
/* 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. These functions must be
AS-safe, with the exception of the actual cancellation, because they
are called by wrappers around AS-safe functions like write().*/
int
__pthread_enable_asynccancel (void)
{
struct pthread *self = THREAD_SELF;
int oldval = THREAD_GETMEM (self, cancelhandling);
while (1)
{
int newval = oldval | CANCELTYPE_BITMASK;
if (newval == oldval)
break;
int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
oldval);
if (__glibc_likely (curval == oldval))
{
if (CANCEL_ENABLED_AND_CANCELED_AND_ASYNCHRONOUS (newval))
{
THREAD_SETMEM (self, result, PTHREAD_CANCELED);
__do_cancel ();
}
break;
}
/* Prepare the next round. */
oldval = curval;
}
return oldval;
}
libc_hidden_def (__pthread_enable_asynccancel)
/* See the comment for __pthread_enable_asynccancel regarding
the AS-safety of this function. */
void
__pthread_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;
int curval = THREAD_ATOMIC_CMPXCHG_VAL (self, cancelhandling, newval,
oldval);
if (__glibc_likely (curval == oldval))
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))
{
futex_wait_simple ((unsigned int *) &self->cancelhandling, newval,
FUTEX_PRIVATE);
newval = THREAD_GETMEM (self, cancelhandling);
}
}
libc_hidden_def (__pthread_disable_asynccancel)