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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 2 | pj | 1 | |
| 1063 | tullio | 2 | /* |
| 3 | * This program is free software; you can redistribute it and/or modify |
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| 4 | * it under the terms of the GNU General Public License as published by |
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| 5 | * the Free Software Foundation; either version 2 of the License, or |
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| 6 | * (at your option) any later version. |
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| 7 | * |
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| 8 | * This program is distributed in the hope that it will be useful, |
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| 9 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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| 11 | * GNU General Public License for more details. |
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| 12 | * |
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| 13 | * You should have received a copy of the GNU General Public License |
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| 14 | * along with this program; if not, write to the Free Software |
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| 15 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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| 16 | * |
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| 17 | */ |
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| 18 | |||
| 2 | pj | 19 | #include <fs/mutex.h> |
| 20 | #include <fs/semaph.h> |
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| 21 | #include "mutex.h" |
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| 22 | #include "rwlock.h" |
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| 23 | |||
| 24 | void __rwlock_init(__rwlock_t *ptr) |
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| 25 | { |
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| 26 | __mutex_init(&ptr->mutex,fsmutexattr); |
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| 27 | __sem_init(&ptr->readers_semaph,0); |
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| 28 | __sem_init(&ptr->writers_semaph,0); |
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| 29 | ptr->active_readers=0; |
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| 30 | ptr->active_writers=0; |
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| 31 | ptr->blocked_readers=0; |
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| 32 | ptr->blocked_writers=0; |
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| 33 | } |
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| 34 | |||
| 35 | void __rwlock_rdlock(__rwlock_t *ptr) |
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| 36 | { |
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| 37 | __mutex_lock(&ptr->mutex); |
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| 38 | |||
| 39 | if (ptr->active_writers==0&&ptr->blocked_writers==0) { |
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| 40 | ptr->active_readers++; |
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| 41 | __sem_signal(&ptr->readers_semaph); |
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| 42 | } else |
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| 43 | ptr->blocked_readers++; |
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| 44 | |||
| 45 | __mutex_unlock(&ptr->mutex); |
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| 46 | |||
| 47 | __sem_wait(&ptr->readers_semaph); |
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| 48 | } |
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| 49 | |||
| 50 | int __rwlock_tryrdlock(__rwlock_t *ptr) |
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| 51 | { |
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| 52 | int ret; |
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| 53 | |||
| 54 | __mutex_lock(&ptr->mutex); |
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| 55 | |||
| 56 | ret=0; |
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| 57 | if (ptr->active_writers==0&&ptr->blocked_writers==0) { |
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| 58 | ptr->active_readers++; |
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| 59 | __sem_signal(&ptr->readers_semaph); |
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| 60 | } else |
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| 61 | ret=-1; |
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| 62 | |||
| 63 | __mutex_unlock(&ptr->mutex); |
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| 64 | |||
| 65 | if (ret==0) __sem_wait(&ptr->readers_semaph); |
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| 66 | return ret; |
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| 67 | } |
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| 68 | |||
| 69 | void __rwlock_wrlock(__rwlock_t *ptr) |
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| 70 | { |
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| 71 | __mutex_lock(&ptr->mutex); |
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| 72 | |||
| 73 | if (ptr->active_readers==0&&ptr->active_writers==0) { |
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| 74 | ptr->active_writers=1; |
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| 75 | __sem_signal(&ptr->writers_semaph); |
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| 76 | } |
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| 77 | else |
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| 78 | ptr->blocked_writers++; |
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| 79 | |||
| 80 | __mutex_unlock(&ptr->mutex); |
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| 81 | |||
| 82 | __sem_wait(&ptr->writers_semaph); |
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| 83 | } |
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| 84 | |||
| 85 | int __rwlock_trywrlock(__rwlock_t *ptr) |
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| 86 | { |
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| 87 | int ret; |
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| 88 | |||
| 89 | __mutex_lock(&ptr->mutex); |
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| 90 | |||
| 91 | ret=0; |
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| 92 | if (ptr->active_readers==0&&ptr->active_writers==0) { |
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| 93 | ptr->active_writers=1; |
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| 94 | __sem_signal(&ptr->writers_semaph); |
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| 95 | } |
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| 96 | else |
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| 97 | ret=-1; |
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| 98 | |||
| 99 | __mutex_unlock(&ptr->mutex); |
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| 100 | |||
| 101 | if (ret==0) __sem_wait(&ptr->writers_semaph); |
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| 102 | return ret; |
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| 103 | } |
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| 104 | |||
| 105 | void __rwlock_rdunlock(__rwlock_t *ptr) |
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| 106 | { |
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| 107 | __mutex_lock(&ptr->mutex); |
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| 108 | |||
| 109 | ptr->active_readers--; |
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| 110 | if (ptr->active_readers==0&&ptr->blocked_writers>0) { |
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| 111 | ptr->active_writers=1; |
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| 112 | ptr->blocked_writers--; |
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| 113 | __sem_signal(&ptr->writers_semaph); |
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| 114 | } |
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| 115 | |||
| 116 | __mutex_unlock(&ptr->mutex); |
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| 117 | } |
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| 118 | |||
| 119 | void __rwlock_wrunlock(__rwlock_t *ptr) |
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| 120 | { |
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| 121 | __mutex_lock(&ptr->mutex); |
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| 122 | |||
| 123 | ptr->active_writers=0; |
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| 124 | if (ptr->blocked_readers>0) { |
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| 125 | do { |
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| 126 | ptr->blocked_readers--; |
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| 127 | ptr->active_readers++; |
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| 128 | __sem_signal(&ptr->readers_semaph); |
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| 129 | } while(ptr->blocked_readers!=0); |
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| 130 | } else if (ptr->blocked_writers>0) { |
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| 131 | ptr->active_writers=1; |
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| 132 | ptr->blocked_writers--; |
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| 133 | __sem_signal(&ptr->writers_semaph); |
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| 134 | } |
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| 135 | |||
| 136 | __mutex_unlock(&ptr->mutex); |
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| 137 | } |