projects / mirror_ubuntu-jammy-kernel.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 LT |
1 | /* |
| 2 | * Copyright (c) 2000-2004 Silicon Graphics, Inc. All Rights Reserved. | |
| 3 | * | |
| 4 | * This program is free software; you can redistribute it and/or modify it | |
| 5 | * under the terms of version 2 of the GNU General Public License as | |
| 6 | * published by the Free Software Foundation. | |
| 7 | * | |
| 8 | * This program is distributed in the hope that it would be useful, but | |
| 9 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. | |
| 11 | * | |
| 12 | * Further, this software is distributed without any warranty that it is | |
| 13 | * free of the rightful claim of any third person regarding infringement | |
| 14 | * or the like. Any license provided herein, whether implied or | |
| 15 | * otherwise, applies only to this software file. Patent licenses, if | |
| 16 | * any, provided herein do not apply to combinations of this program with | |
| 17 | * other software, or any other product whatsoever. | |
| 18 | * | |
| 19 | * You should have received a copy of the GNU General Public License along | |
| 20 | * with this program; if not, write the Free Software Foundation, Inc., 59 | |
| 21 | * Temple Place - Suite 330, Boston MA 02111-1307, USA. | |
| 22 | * | |
| 23 | * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy, | |
| 24 | * Mountain View, CA 94043, or: | |
| 25 | * | |
| 26 | * http://www.sgi.com | |
| 27 | * | |
| 28 | * For further information regarding this notice, see: | |
| 29 | * | |
| 30 | * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/ | |
| 31 | */ | |
| 32 | #ifndef __XFS_SUPPORT_MRLOCK_H__ | |
| 33 | #define __XFS_SUPPORT_MRLOCK_H__ | |
| 34 | ||
| 35 | #include <linux/rwsem.h> | |
| 36 | ||
| 37 | enum { MR_NONE, MR_ACCESS, MR_UPDATE }; | |
| 38 | ||
| 39 | typedef struct { | |
| 40 | struct rw_semaphore mr_lock; | |
| 41 | int mr_writer; | |
| 42 | } mrlock_t; | |
| 43 | ||
| 44 | #define mrinit(mrp, name) \ | |
| 45 | ( (mrp)->mr_writer = 0, init_rwsem(&(mrp)->mr_lock) ) | |
| 46 | #define mrlock_init(mrp, t,n,s) mrinit(mrp, n) | |
| 47 | #define mrfree(mrp) do { } while (0) | |
| 48 | #define mraccess(mrp) mraccessf(mrp, 0) | |
| 49 | #define mrupdate(mrp) mrupdatef(mrp, 0) | |
| 50 | ||
| 51 | static inline void mraccessf(mrlock_t *mrp, int flags) | |
| 52 | { | |
| 53 | down_read(&mrp->mr_lock); | |
| 54 | } | |
| 55 | ||
| 56 | static inline void mrupdatef(mrlock_t *mrp, int flags) | |
| 57 | { | |
| 58 | down_write(&mrp->mr_lock); | |
| 59 | mrp->mr_writer = 1; | |
| 60 | } | |
| 61 | ||
| 62 | static inline int mrtryaccess(mrlock_t *mrp) | |
| 63 | { | |
| 64 | return down_read_trylock(&mrp->mr_lock); | |
| 65 | } | |
| 66 | ||
| 67 | static inline int mrtryupdate(mrlock_t *mrp) | |
| 68 | { | |
| 69 | if (!down_write_trylock(&mrp->mr_lock)) | |
| 70 | return 0; | |
| 71 | mrp->mr_writer = 1; | |
| 72 | return 1; | |
| 73 | } | |
| 74 | ||
| 75 | static inline void mrunlock(mrlock_t *mrp) | |
| 76 | { | |
| 77 | if (mrp->mr_writer) { | |
| 78 | mrp->mr_writer = 0; | |
| 79 | up_write(&mrp->mr_lock); | |
| 80 | } else { | |
| 81 | up_read(&mrp->mr_lock); | |
| 82 | } | |
| 83 | } | |
| 84 | ||
| 85 | static inline void mrdemote(mrlock_t *mrp) | |
| 86 | { | |
| 87 | mrp->mr_writer = 0; | |
| 88 | downgrade_write(&mrp->mr_lock); | |
| 89 | } | |
| 90 | ||
| 91 | #ifdef DEBUG | |
| 92 | /* | |
| 93 | * Debug-only routine, without some platform-specific asm code, we can | |
| 94 | * now only answer requests regarding whether we hold the lock for write | |
| 95 | * (reader state is outside our visibility, we only track writer state). | |
| 96 | * Note: means !ismrlocked would give false positivies, so don't do that. | |
| 97 | */ | |
| 98 | static inline int ismrlocked(mrlock_t *mrp, int type) | |
| 99 | { | |
| 100 | if (mrp && type == MR_UPDATE) | |
| 101 | return mrp->mr_writer; | |
| 102 | return 1; | |
| 103 | } | |
| 104 | #endif | |
| 105 | ||
| 106 | #endif /* __XFS_SUPPORT_MRLOCK_H__ */ |