mirror_zfs/include/linux/compiler_compat.h
Ricardo M. Correia 22cd0f19b1 Fix compilation error due to undefined ACCESS_ONCE macro.
When CONFIG_DEBUG_MUTEXES is turned on in RHEL5's kernel config, the mutexes
store the owner for debugging purposes, therefore the SPL will enable
HAVE_MUTEX_OWNER. However, the SPL code uses ACCESS_ONCE() to access the
owner, and this macro is not defined in the RHEL5 kernel, therefore we define it
ourselves in include/linux/compiler_compat.h.

Signed-off-by: Ricardo M. Correia <ricardo.correia@oracle.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
2010-07-20 13:47:52 -07:00

48 lines
2.0 KiB
C

/*****************************************************************************\
* Copyright (C) 2007-2010 Lawrence Livermore National Security, LLC.
* Copyright (C) 2007 The Regents of the University of California.
* Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
* Written by Brian Behlendorf <behlendorf1@llnl.gov>.
* UCRL-CODE-235197
*
* This file is part of the SPL, Solaris Porting Layer.
* For details, see <http://github.com/behlendorf/spl/>.
*
* The SPL is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* The SPL 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 General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with the SPL. If not, see <http://www.gnu.org/licenses/>.
\*****************************************************************************/
#ifndef _SPL_COMPILER_COMPAT_H
#define _SPL_COMPILER_COMPAT_H
#include <linux/compiler.h>
#ifndef ACCESS_ONCE
/*
* Prevent the compiler from merging or refetching accesses. The compiler
* is also forbidden from reordering successive instances of ACCESS_ONCE(),
* but only when the compiler is aware of some particular ordering. One way
* to make the compiler aware of ordering is to put the two invocations of
* ACCESS_ONCE() in different C statements.
*
* This macro does absolutely -nothing- to prevent the CPU from reordering,
* merging, or refetching absolutely anything at any time. Its main intended
* use is to mediate communication between process-level code and irq/NMI
* handlers, all running on the same CPU.
*/
/* Taken from 2.6.33.2 */
# define ACCESS_ONCE(x) (*(volatile typeof(x) *)&(x))
#endif
#endif /* _SPL_COMPILER_COMPAT_H */