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107 lines
2.9 KiB
107 lines
2.9 KiB
20 years ago
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/*
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* Copyright (c) 2000-2004 Silicon Graphics, Inc. All Rights Reserved.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of version 2 of the GNU General Public License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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*
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* Further, this software is distributed without any warranty that it is
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* free of the rightful claim of any third person regarding infringement
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* or the like. Any license provided herein, whether implied or
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* otherwise, applies only to this software file. Patent licenses, if
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* any, provided herein do not apply to combinations of this program with
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* other software, or any other product whatsoever.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write the Free Software Foundation, Inc., 59
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* Temple Place - Suite 330, Boston MA 02111-1307, USA.
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*
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* Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
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* Mountain View, CA 94043, or:
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*
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* http://www.sgi.com
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*
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* For further information regarding this notice, see:
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*
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* http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
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*/
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#ifndef __XFS_SUPPORT_MRLOCK_H__
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#define __XFS_SUPPORT_MRLOCK_H__
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#include <linux/rwsem.h>
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enum { MR_NONE, MR_ACCESS, MR_UPDATE };
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typedef struct {
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struct rw_semaphore mr_lock;
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int mr_writer;
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} mrlock_t;
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#define mrinit(mrp, name) \
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( (mrp)->mr_writer = 0, init_rwsem(&(mrp)->mr_lock) )
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#define mrlock_init(mrp, t,n,s) mrinit(mrp, n)
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#define mrfree(mrp) do { } while (0)
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#define mraccess(mrp) mraccessf(mrp, 0)
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#define mrupdate(mrp) mrupdatef(mrp, 0)
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static inline void mraccessf(mrlock_t *mrp, int flags)
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{
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down_read(&mrp->mr_lock);
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}
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static inline void mrupdatef(mrlock_t *mrp, int flags)
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{
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down_write(&mrp->mr_lock);
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mrp->mr_writer = 1;
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}
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static inline int mrtryaccess(mrlock_t *mrp)
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{
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return down_read_trylock(&mrp->mr_lock);
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}
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static inline int mrtryupdate(mrlock_t *mrp)
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{
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if (!down_write_trylock(&mrp->mr_lock))
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return 0;
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mrp->mr_writer = 1;
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return 1;
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}
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static inline void mrunlock(mrlock_t *mrp)
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{
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if (mrp->mr_writer) {
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mrp->mr_writer = 0;
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up_write(&mrp->mr_lock);
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} else {
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up_read(&mrp->mr_lock);
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}
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}
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static inline void mrdemote(mrlock_t *mrp)
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{
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mrp->mr_writer = 0;
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downgrade_write(&mrp->mr_lock);
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}
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#ifdef DEBUG
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/*
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* Debug-only routine, without some platform-specific asm code, we can
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* now only answer requests regarding whether we hold the lock for write
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* (reader state is outside our visibility, we only track writer state).
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* Note: means !ismrlocked would give false positivies, so don't do that.
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*/
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static inline int ismrlocked(mrlock_t *mrp, int type)
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{
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if (mrp && type == MR_UPDATE)
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return mrp->mr_writer;
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return 1;
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}
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#endif
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#endif /* __XFS_SUPPORT_MRLOCK_H__ */
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