projects / deliverable / linux.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 | 1 | /* |
| 72c93bcc | 2 | * Copyright (c) 2000-2006 Silicon Graphics, Inc. |
| 7b718769 | 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) \ | |
| 72c93bcc | 31 | do { (mrp)->mr_writer = 0; init_rwsem(&(mrp)->mr_lock); } while (0) |
| 1da177e4 LT |
32 | #define mrlock_init(mrp, t,n,s) mrinit(mrp, n) |
| 33 | #define mrfree(mrp) do { } while (0) | |
| 1da177e4 | 34 | |
| a3227fb9 | 35 | static inline void mraccess(mrlock_t *mrp) |
| 1da177e4 LT |
36 | { |
| 37 | down_read(&mrp->mr_lock); | |
| 38 | } | |
| 39 | ||
| a3227fb9 | 40 | static inline void mrupdate(mrlock_t *mrp) |
| 1da177e4 LT |
41 | { |
| 42 | down_write(&mrp->mr_lock); | |
| 43 | mrp->mr_writer = 1; | |
| 44 | } | |
| 45 | ||
| f7c66ce3 LM |
46 | static inline void mraccess_nested(mrlock_t *mrp, int subclass) |
| 47 | { | |
| 48 | down_read_nested(&mrp->mr_lock, subclass); | |
| 49 | } | |
| 50 | ||
| 51 | static inline void mrupdate_nested(mrlock_t *mrp, int subclass) | |
| 52 | { | |
| 53 | down_write_nested(&mrp->mr_lock, subclass); | |
| 54 | mrp->mr_writer = 1; | |
| 55 | } | |
| 56 | ||
| 57 | ||
| 1da177e4 LT |
58 | static inline int mrtryaccess(mrlock_t *mrp) |
| 59 | { | |
| 60 | return down_read_trylock(&mrp->mr_lock); | |
| 61 | } | |
| 62 | ||
| 63 | static inline int mrtryupdate(mrlock_t *mrp) | |
| 64 | { | |
| 65 | if (!down_write_trylock(&mrp->mr_lock)) | |
| 66 | return 0; | |
| 67 | mrp->mr_writer = 1; | |
| 68 | return 1; | |
| 69 | } | |
| 70 | ||
| 71 | static inline void mrunlock(mrlock_t *mrp) | |
| 72 | { | |
| 73 | if (mrp->mr_writer) { | |
| 74 | mrp->mr_writer = 0; | |
| 75 | up_write(&mrp->mr_lock); | |
| 76 | } else { | |
| 77 | up_read(&mrp->mr_lock); | |
| 78 | } | |
| 79 | } | |
| 80 | ||
| 81 | static inline void mrdemote(mrlock_t *mrp) | |
| 82 | { | |
| 83 | mrp->mr_writer = 0; | |
| 84 | downgrade_write(&mrp->mr_lock); | |
| 85 | } | |
| 86 | ||
| 87 | #ifdef DEBUG | |
| 88 | /* | |
| 89 | * Debug-only routine, without some platform-specific asm code, we can | |
| 90 | * now only answer requests regarding whether we hold the lock for write | |
| 91 | * (reader state is outside our visibility, we only track writer state). | |
| c41564b5 | 92 | * Note: means !ismrlocked would give false positives, so don't do that. |
| 1da177e4 LT |
93 | */ |
| 94 | static inline int ismrlocked(mrlock_t *mrp, int type) | |
| 95 | { | |
| 96 | if (mrp && type == MR_UPDATE) | |
| 97 | return mrp->mr_writer; | |
| 98 | return 1; | |
| 99 | } | |
| 100 | #endif | |
| 101 | ||
| 102 | #endif /* __XFS_SUPPORT_MRLOCK_H__ */ |