projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 | 1 | /* |
| 7b718769 NS |
2 | * Copyright (c) 2000-2005 Silicon Graphics, Inc. |
| 3 | * All Rights Reserved. | |
| 1da177e4 | 4 | * |
| 7b718769 NS |
5 | * This program is free software; you can redistribute it and/or |
| 6 | * modify it under the terms of the GNU General Public License as | |
| 1da177e4 LT |
7 | * published by the Free Software Foundation. |
| 8 | * | |
| 7b718769 NS |
9 | * This program is distributed in the hope that it would be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 12 | * GNU General Public License for more details. | |
| 1da177e4 | 13 | * |
| 7b718769 NS |
14 | * You should have received a copy of the GNU General Public License |
| 15 | * along with this program; if not, write the Free Software Foundation, | |
| 16 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | |
| 1da177e4 LT |
17 | */ |
| 18 | #ifndef __XFS_SUPPORT_MRLOCK_H__ | |
| 19 | #define __XFS_SUPPORT_MRLOCK_H__ | |
| 20 | ||
| 21 | #include <linux/rwsem.h> | |
| 22 | ||
| 23 | enum { MR_NONE, MR_ACCESS, MR_UPDATE }; | |
| 24 | ||
| 25 | typedef struct { | |
| 26 | struct rw_semaphore mr_lock; | |
| 27 | int mr_writer; | |
| 28 | } mrlock_t; | |
| 29 | ||
| 30 | #define mrinit(mrp, name) \ | |
| 31 | ( (mrp)->mr_writer = 0, init_rwsem(&(mrp)->mr_lock) ) | |
| 32 | #define mrlock_init(mrp, t,n,s) mrinit(mrp, n) | |
| 33 | #define mrfree(mrp) do { } while (0) | |
| 34 | #define mraccess(mrp) mraccessf(mrp, 0) | |
| 35 | #define mrupdate(mrp) mrupdatef(mrp, 0) | |
| 36 | ||
| 37 | static inline void mraccessf(mrlock_t *mrp, int flags) | |
| 38 | { | |
| 39 | down_read(&mrp->mr_lock); | |
| 40 | } | |
| 41 | ||
| 42 | static inline void mrupdatef(mrlock_t *mrp, int flags) | |
| 43 | { | |
| 44 | down_write(&mrp->mr_lock); | |
| 45 | mrp->mr_writer = 1; | |
| 46 | } | |
| 47 | ||
| 48 | static inline int mrtryaccess(mrlock_t *mrp) | |
| 49 | { | |
| 50 | return down_read_trylock(&mrp->mr_lock); | |
| 51 | } | |
| 52 | ||
| 53 | static inline int mrtryupdate(mrlock_t *mrp) | |
| 54 | { | |
| 55 | if (!down_write_trylock(&mrp->mr_lock)) | |
| 56 | return 0; | |
| 57 | mrp->mr_writer = 1; | |
| 58 | return 1; | |
| 59 | } | |
| 60 | ||
| 61 | static inline void mrunlock(mrlock_t *mrp) | |
| 62 | { | |
| 63 | if (mrp->mr_writer) { | |
| 64 | mrp->mr_writer = 0; | |
| 65 | up_write(&mrp->mr_lock); | |
| 66 | } else { | |
| 67 | up_read(&mrp->mr_lock); | |
| 68 | } | |
| 69 | } | |
| 70 | ||
| 71 | static inline void mrdemote(mrlock_t *mrp) | |
| 72 | { | |
| 73 | mrp->mr_writer = 0; | |
| 74 | downgrade_write(&mrp->mr_lock); | |
| 75 | } | |
| 76 | ||
| 77 | #ifdef DEBUG | |
| 78 | /* | |
| 79 | * Debug-only routine, without some platform-specific asm code, we can | |
| 80 | * now only answer requests regarding whether we hold the lock for write | |
| 81 | * (reader state is outside our visibility, we only track writer state). | |
| c41564b5 | 82 | * Note: means !ismrlocked would give false positives, so don't do that. |
| 1da177e4 LT |
83 | */ |
| 84 | static inline int ismrlocked(mrlock_t *mrp, int type) | |
| 85 | { | |
| 86 | if (mrp && type == MR_UPDATE) | |
| 87 | return mrp->mr_writer; | |
| 88 | return 1; | |
| 89 | } | |
| 90 | #endif | |
| 91 | ||
| 92 | #endif /* __XFS_SUPPORT_MRLOCK_H__ */ |