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001 /* Copyright (C) 2004 David Decotigny 001 /* Copyright (C) 2004 David Decotigny 002 002 003 This program is free software; you can redi 003 This program is free software; you can redistribute it and/or 004 modify it under the terms of the GNU Genera 004 modify it under the terms of the GNU General Public License 005 as published by the Free Software Foundatio 005 as published by the Free Software Foundation; either version 2 006 of the License, or (at your option) any lat 006 of the License, or (at your option) any later version. 007 007 008 This program is distributed in the hope tha 008 This program is distributed in the hope that it will be useful, 009 but WITHOUT ANY WARRANTY; without even the 009 but WITHOUT ANY WARRANTY; without even the implied warranty of 010 MERCHANTABILITY or FITNESS FOR A PARTICULAR 010 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 011 GNU General Public License for more details 011 GNU General Public License for more details. 012 012 013 You should have received a copy of the GNU 013 You should have received a copy of the GNU General Public License 014 along with this program; if not, write to t 014 along with this program; if not, write to the Free Software 015 Foundation, Inc., 59 Temple Place - Suite 3 015 Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 016 USA. 016 USA. 017 */ 017 */ 018 018 019 019 020 #include <hwcore/irq.h> 020 #include <hwcore/irq.h> 021 #include <sos/assert.h> << 022 021 023 022 024 #include "ksynch.h" 023 #include "ksynch.h" 025 024 026 025 027 sos_ret_t sos_ksema_init(struct sos_ksema *sem 026 sos_ret_t sos_ksema_init(struct sos_ksema *sema, const char *name, 028 int initial_value, 027 int initial_value, 029 sos_kwaitq_ordering_t 028 sos_kwaitq_ordering_t ordering) 030 { 029 { 031 sema->value = initial_value; 030 sema->value = initial_value; 032 return sos_kwaitq_init(& sema->kwaitq, name, 031 return sos_kwaitq_init(& sema->kwaitq, name, ordering); 033 } 032 } 034 033 035 034 036 sos_ret_t sos_ksema_dispose(struct sos_ksema * 035 sos_ret_t sos_ksema_dispose(struct sos_ksema *sema) 037 { 036 { 038 return sos_kwaitq_dispose(& sema->kwaitq); 037 return sos_kwaitq_dispose(& sema->kwaitq); 039 } 038 } 040 039 041 040 042 sos_ret_t sos_ksema_down(struct sos_ksema *sem 041 sos_ret_t sos_ksema_down(struct sos_ksema *sema, 043 struct sos_time *time 042 struct sos_time *timeout) 044 { 043 { 045 sos_ui32_t flags; 044 sos_ui32_t flags; 046 sos_ret_t retval; 045 sos_ret_t retval; 047 046 048 sos_disable_IRQs(flags); 047 sos_disable_IRQs(flags); 049 retval = SOS_OK; 048 retval = SOS_OK; 050 049 051 sema->value --; 050 sema->value --; 052 if (sema->value < 0) 051 if (sema->value < 0) 053 { 052 { 054 /* Wait for somebody to wake us */ 053 /* Wait for somebody to wake us */ 055 retval = sos_kwaitq_wait(& sema->kwaitq, 054 retval = sos_kwaitq_wait(& sema->kwaitq, timeout); 056 055 057 /* Something wrong happened (timeout, ex 056 /* Something wrong happened (timeout, external wakeup, ...) ? */ 058 if (SOS_OK != retval) 057 if (SOS_OK != retval) 059 { 058 { 060 /* Yes: pretend we did not ask for t 059 /* Yes: pretend we did not ask for the semaphore */ 061 sema->value ++; 060 sema->value ++; 062 } 061 } 063 } 062 } 064 063 065 sos_restore_IRQs(flags); 064 sos_restore_IRQs(flags); 066 return retval; 065 return retval; 067 } 066 } 068 067 069 068 070 sos_ret_t sos_ksema_trydown(struct sos_ksema * 069 sos_ret_t sos_ksema_trydown(struct sos_ksema *sema) 071 { 070 { 072 sos_ui32_t flags; 071 sos_ui32_t flags; 073 sos_ret_t retval; 072 sos_ret_t retval; 074 073 075 sos_disable_IRQs(flags); 074 sos_disable_IRQs(flags); 076 075 077 /* Can we take the semaphore without blockin 076 /* Can we take the semaphore without blocking ? */ 078 if (sema->value >= 1) 077 if (sema->value >= 1) 079 { 078 { 080 /* Yes: we take it now */ 079 /* Yes: we take it now */ 081 sema->value --; 080 sema->value --; 082 retval = SOS_OK; 081 retval = SOS_OK; 083 } 082 } 084 else 083 else 085 { 084 { 086 /* No: we signal it */ 085 /* No: we signal it */ 087 retval = -SOS_EBUSY; 086 retval = -SOS_EBUSY; 088 } 087 } 089 088 090 sos_restore_IRQs(flags); 089 sos_restore_IRQs(flags); 091 return retval; 090 return retval; 092 } 091 } 093 092 094 093 095 sos_ret_t sos_ksema_up(struct sos_ksema *sema) 094 sos_ret_t sos_ksema_up(struct sos_ksema *sema) 096 { 095 { 097 sos_ui32_t flags; 096 sos_ui32_t flags; 098 sos_ret_t retval; 097 sos_ret_t retval; 099 098 100 sos_disable_IRQs(flags); 099 sos_disable_IRQs(flags); 101 100 102 sema->value ++; 101 sema->value ++; 103 retval = sos_kwaitq_wakeup(& sema->kwaitq, 1 102 retval = sos_kwaitq_wakeup(& sema->kwaitq, 1, SOS_OK); 104 103 105 sos_restore_IRQs(flags); 104 sos_restore_IRQs(flags); 106 return retval; 105 return retval; 107 } 106 } 108 107 109 108 110 sos_ret_t sos_kmutex_init(struct sos_kmutex *m 109 sos_ret_t sos_kmutex_init(struct sos_kmutex *mutex, const char *name, 111 sos_kwaitq_ordering_ 110 sos_kwaitq_ordering_t ordering) 112 { 111 { 113 mutex->owner = NULL; 112 mutex->owner = NULL; 114 return sos_kwaitq_init(& mutex->kwaitq, name 113 return sos_kwaitq_init(& mutex->kwaitq, name, ordering); 115 } 114 } 116 115 117 116 118 sos_ret_t sos_kmutex_dispose(struct sos_kmutex 117 sos_ret_t sos_kmutex_dispose(struct sos_kmutex *mutex) 119 { 118 { 120 return sos_kwaitq_dispose(& mutex->kwaitq); 119 return sos_kwaitq_dispose(& mutex->kwaitq); 121 } 120 } 122 121 123 122 124 /* 123 /* 125 * Implementation based on ownership transfer 124 * Implementation based on ownership transfer (ie no while() 126 * loop). The only assumption is that the thre 125 * loop). The only assumption is that the thread awoken by 127 * kmutex_unlock is not suppressed before effe 126 * kmutex_unlock is not suppressed before effectively waking up: in 128 * that case the mutex will be forever locked 127 * that case the mutex will be forever locked AND unlockable (by 129 * nobody other than the owner, but this is no 128 * nobody other than the owner, but this is not natural since this 130 * owner already issued an unlock()...). The s 129 * owner already issued an unlock()...). The same problem happens with 131 * the semaphores, but in a less obvious manne 130 * the semaphores, but in a less obvious manner. 132 */ 131 */ 133 sos_ret_t sos_kmutex_lock(struct sos_kmutex *m 132 sos_ret_t sos_kmutex_lock(struct sos_kmutex *mutex, 134 struct sos_time *tim 133 struct sos_time *timeout) 135 { 134 { 136 __label__ exit_kmutex_lock; 135 __label__ exit_kmutex_lock; 137 sos_ui32_t flags; 136 sos_ui32_t flags; 138 sos_ret_t retval; 137 sos_ret_t retval; 139 138 140 sos_disable_IRQs(flags); 139 sos_disable_IRQs(flags); 141 retval = SOS_OK; 140 retval = SOS_OK; 142 141 143 /* Mutex already owned ? */ 142 /* Mutex already owned ? */ 144 if (NULL != mutex->owner) 143 if (NULL != mutex->owner) 145 { 144 { 146 /* Owned by us or by someone else ? */ 145 /* Owned by us or by someone else ? */ 147 if (sos_thread_get_current() == mutex->o 146 if (sos_thread_get_current() == mutex->owner) 148 { 147 { 149 /* Owned by us: do nothing */ 148 /* Owned by us: do nothing */ 150 retval = -SOS_EBUSY; 149 retval = -SOS_EBUSY; 151 goto exit_kmutex_lock; 150 goto exit_kmutex_lock; 152 } 151 } 153 152 154 /* Wait for somebody to wake us */ 153 /* Wait for somebody to wake us */ 155 retval = sos_kwaitq_wait(& mutex->kwaitq 154 retval = sos_kwaitq_wait(& mutex->kwaitq, timeout); 156 155 157 /* Something wrong happened ? */ 156 /* Something wrong happened ? */ 158 if (SOS_OK != retval) 157 if (SOS_OK != retval) 159 { 158 { 160 goto exit_kmutex_lock; 159 goto exit_kmutex_lock; 161 } 160 } 162 } 161 } 163 162 164 /* Ok, the mutex is available to us: take it 163 /* Ok, the mutex is available to us: take it */ 165 mutex->owner = sos_thread_get_current(); 164 mutex->owner = sos_thread_get_current(); 166 165 167 exit_kmutex_lock: 166 exit_kmutex_lock: 168 sos_restore_IRQs(flags); 167 sos_restore_IRQs(flags); 169 return retval; 168 return retval; 170 } 169 } 171 170 172 171 173 sos_bool_t sos_kmutex_owned_by_me(struct sos_k << 174 { << 175 sos_ui32_t flags; << 176 sos_bool_t retval; << 177 << 178 sos_disable_IRQs(flags); << 179 retval = (sos_thread_get_current() == mutex- << 180 sos_restore_IRQs(flags); << 181 << 182 return retval; << 183 } << 184 << 185 << 186 sos_ret_t sos_kmutex_trylock(struct sos_kmutex 172 sos_ret_t sos_kmutex_trylock(struct sos_kmutex *mutex) 187 { 173 { 188 sos_ui32_t flags; 174 sos_ui32_t flags; 189 sos_ret_t retval; 175 sos_ret_t retval; 190 176 191 sos_disable_IRQs(flags); 177 sos_disable_IRQs(flags); 192 178 193 /* Mutex available to us ? */ 179 /* Mutex available to us ? */ 194 if (NULL == mutex->owner) 180 if (NULL == mutex->owner) 195 { 181 { 196 /* Great ! Take it now */ 182 /* Great ! Take it now */ 197 mutex->owner = sos_thread_get_current(); 183 mutex->owner = sos_thread_get_current(); 198 184 199 retval = SOS_OK; 185 retval = SOS_OK; 200 } 186 } 201 else 187 else 202 { 188 { 203 /* No: signal it */ 189 /* No: signal it */ 204 retval = -SOS_EBUSY; 190 retval = -SOS_EBUSY; 205 } 191 } 206 192 207 sos_restore_IRQs(flags); 193 sos_restore_IRQs(flags); 208 return retval; 194 return retval; 209 } 195 } 210 196 211 197 212 sos_ret_t sos_kmutex_unlock(struct sos_kmutex 198 sos_ret_t sos_kmutex_unlock(struct sos_kmutex *mutex) 213 { 199 { 214 sos_ui32_t flags; 200 sos_ui32_t flags; 215 sos_ret_t retval; 201 sos_ret_t retval; 216 202 217 sos_disable_IRQs(flags); 203 sos_disable_IRQs(flags); 218 204 219 if (sos_thread_get_current() != mutex->owner 205 if (sos_thread_get_current() != mutex->owner) 220 retval = -SOS_EPERM; 206 retval = -SOS_EPERM; 221 207 222 else if (sos_kwaitq_is_empty(& mutex->kwaitq 208 else if (sos_kwaitq_is_empty(& mutex->kwaitq)) 223 { 209 { 224 /* 210 /* 225 * There is NOT ANY thread waiting => we 211 * There is NOT ANY thread waiting => we really mark the mutex 226 * as FREE 212 * as FREE 227 */ 213 */ 228 mutex->owner = NULL; 214 mutex->owner = NULL; 229 retval = SOS_OK; 215 retval = SOS_OK; 230 } 216 } 231 else 217 else 232 { 218 { 233 /* 219 /* 234 * There is at least 1 thread waiting => 220 * There is at least 1 thread waiting => we DO NOT mark the 235 * mutex as free ! 221 * mutex as free ! 236 * Actually, we should have written: 222 * Actually, we should have written: 237 * mutex->owner = thread_that_is_woken 223 * mutex->owner = thread_that_is_woken_up; 238 * But the real Id of the next thread ow 224 * But the real Id of the next thread owning the mutex is not 239 * that important. What is important her 225 * that important. What is important here is that mutex->owner 240 * IS NOT NULL and does not correspond t !! 226 * IS NOT NULL. Otherwise there will be a possibility for the 241 * (address 0x43 is a good candidate bec << 242 * below 4kB are never mapped in order t << 243 * pointers). Otherwise there will be a << 244 * thread woken up here to have the mute 227 * thread woken up here to have the mutex stolen by a thread 245 * locking the mutex in the meantime. 228 * locking the mutex in the meantime. 246 */ 229 */ 247 #define MUTEX_STILL_LOCKED ((struct sos_thread << 248 mutex->owner = MUTEX_STILL_LOCKED; << 249 << 250 /* We wake up ONE thread ONLY */ << 251 retval = sos_kwaitq_wakeup(& mutex->kwai 230 retval = sos_kwaitq_wakeup(& mutex->kwaitq, 1, SOS_OK); 252 } 231 } 253 232 254 sos_restore_IRQs(flags); 233 sos_restore_IRQs(flags); 255 return retval; 234 return retval; 256 } 235 }
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