mirror_zfs/include/linux/compiler_compat.h
Olaf Faaland ce319db57b Make include/linux/ conform to ZFS style standard
No semantic changes.

Fix the following types of style issues:
	blank after preprocessor #
	#define followed by space instead of tab
	improper first line of block comment
	indent by spaces instead of tabs
	last line in file is blank
	missing blank after open comment
	missing space before left brace
	non-continuation indented 4 spaces
	spaces instead of tabs
	unparenthesized return expression

Signed-off-by: Olaf Faaland <faaland1@llnl.gov>
2017-10-09 14:27:27 -07:00

48 lines
1.9 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://zfsonlinux.org/>.
*
* 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 */