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Fix aio_error thread-safety.

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* sysdeps/pthread/aio_error.c: New file
* sysdeps/pthread/aio_misc.c: Remove optimistic comment about
synchronization.
This commit is contained in:
Samuel Thibault 2015-03-06 11:32:24 +01:00
parent 1597b7447a
commit 1cdf2ea1fa
3 changed files with 57 additions and 8 deletions
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8
ChangeLog
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@ -1,3 +1,11 @@
2015-03-06 Samuel Thibault <samuel.thibault@inria.fr>
Fix aio_error thread-safety.
* sysdeps/pthread/aio_error.c: New file
* sysdeps/pthread/aio_misc.c: Remove optimistic comment about
synchronization.
2015-03-06 Florian Weimer <fweimer@redhat.com>
* stdio-common/vfprintf.c (THOUSANDS_SEP_T): New typedef.

49
sysdeps/pthread/aio_error.c Normal file
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@ -0,0 +1,49 @@
/* Return error status of asynchronous I/O request.
Copyright (C) 1997-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
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
<http://www.gnu.org/licenses/>. */
/* We use an UGLY hack to prevent gcc from finding us cheating. The
implementation of aio_error and aio_error64 are identical and so
we want to avoid code duplication by using aliases. But gcc sees
the different parameter lists and prints a warning. We define here
a function so that aio_error64 has no prototype. */
#define aio_error64 XXX
#include <aio.h>
/* And undo the hack. */
#undef aio_error64
#include <aio_misc.h>
int
aio_error (aiocbp)
const struct aiocb *aiocbp;
{
int ret;
/* Acquire the mutex to make sure all operations for this request are
complete. */
pthread_mutex_lock(&__aio_requests_mutex);
ret = aiocbp->__error_code;
pthread_mutex_unlock(&__aio_requests_mutex);
return ret;
}
weak_alias (aio_error, aio_error64)

8
sysdeps/pthread/aio_misc.c
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@ -593,14 +593,6 @@ handle_fildes_io (void *arg)
/* Get the mutex. */
pthread_mutex_lock (&__aio_requests_mutex);
/* In theory we would need here a write memory barrier since the
callers test using aio_error() whether the request finished
and once this value != EINPROGRESS the field __return_value
must be committed to memory.
But since the pthread_mutex_lock call involves write memory
barriers as well it is not necessary. */
if (aiocbp->aiocb.__return_value == -1)
aiocbp->aiocb.__error_code = errno;
else