kernel/spinlock.c

   1 /*
   2  * Copyright (2004) Linus Torvalds
   3  *
   4  * Author: Zwane Mwaikambo <zwane@fsmlabs.com>
   5  */
   6
   7 #include <linux/config.h>
   8 #include <linux/linkage.h>
   9 #include <linux/preempt.h>
  10 #include <linux/spinlock.h>
  11 #include <linux/interrupt.h>
  12 #include <linux/module.h>
  13
  14 int __lockfunc _spin_trylock(spinlock_t *lock)
  15 {
  16         preempt_disable();
  17         if (_raw_spin_trylock(lock))
  18                 return 1;
  19
  20         preempt_enable();
  21         return 0;
  22 }
  23 EXPORT_SYMBOL(_spin_trylock);
  24
  25 int __lockfunc _write_trylock(rwlock_t *lock)
  26 {
  27         preempt_disable();
  28         if (_raw_write_trylock(lock))
  29                 return 1;
  30
  31         preempt_enable();
  32         return 0;
  33 }
  34 EXPORT_SYMBOL(_write_trylock);
  35
  36 #ifdef CONFIG_PREEMPT
  37 /*
  38  * This could be a long-held lock.  If another CPU holds it for a long time,
  39  * and that CPU is not asked to reschedule then *this* CPU will spin on the
  40  * lock for a long time, even if *this* CPU is asked to reschedule.
  41  *
  42  * So what we do here, in the slow (contended) path is to spin on the lock by
  43  * hand while permitting preemption.
  44  *
  45  * Called inside preempt_disable().
  46  */
  47 static inline void __preempt_spin_lock(spinlock_t *lock)
  48 {
  49         if (preempt_count() > 1) {
  50                 _raw_spin_lock(lock);
  51                 return;
  52         }
  53
  54         do {
  55                 preempt_enable();
  56                 while (spin_is_locked(lock))
  57                         cpu_relax();
  58                 preempt_disable();
  59         } while (!_raw_spin_trylock(lock));
  60 }
  61
  62 void __lockfunc _spin_lock(spinlock_t *lock)
  63 {
  64         preempt_disable();
  65         if (unlikely(!_raw_spin_trylock(lock)))
  66                 __preempt_spin_lock(lock);
  67 }
  68
  69 static inline void __preempt_write_lock(rwlock_t *lock)
  70 {
  71         if (preempt_count() > 1) {
  72                 _raw_write_lock(lock);
  73                 return;
  74         }
  75
  76         do {
  77                 preempt_enable();
  78                 while (rwlock_is_locked(lock))
  79                         cpu_relax();
  80                 preempt_disable();
  81         } while (!_raw_write_trylock(lock));
  82 }
  83
  84 void __lockfunc _write_lock(rwlock_t *lock)
  85 {
  86         preempt_disable();
  87         if (unlikely(!_raw_write_trylock(lock)))
  88                 __preempt_write_lock(lock);
  89 }
  90 #else
  91 void __lockfunc _spin_lock(spinlock_t *lock)
  92 {
  93         preempt_disable();
  94         _raw_spin_lock(lock);
  95 }
  96
  97 void __lockfunc _write_lock(rwlock_t *lock)
  98 {
  99         preempt_disable();
 100         _raw_write_lock(lock);
 101 }
 102 #endif
 103 EXPORT_SYMBOL(_spin_lock);
 104 EXPORT_SYMBOL(_write_lock);
 105
 106 void __lockfunc _read_lock(rwlock_t *lock)
 107 {
 108         preempt_disable();
 109         _raw_read_lock(lock);
 110 }
 111 EXPORT_SYMBOL(_read_lock);
 112
 113 void __lockfunc _spin_unlock(spinlock_t *lock)
 114 {
 115         _raw_spin_unlock(lock);
 116         preempt_enable();
 117 }
 118 EXPORT_SYMBOL(_spin_unlock);
 119
 120 void __lockfunc _write_unlock(rwlock_t *lock)
 121 {
 122         _raw_write_unlock(lock);
 123         preempt_enable();
 124 }
 125 EXPORT_SYMBOL(_write_unlock);
 126
 127 void __lockfunc _read_unlock(rwlock_t *lock)
 128 {
 129         _raw_read_unlock(lock);
 130         preempt_enable();
 131 }
 132 EXPORT_SYMBOL(_read_unlock);
 133
 134 unsigned long __lockfunc _spin_lock_irqsave(spinlock_t *lock)
 135 {
 136         unsigned long flags;
 137
 138         local_irq_save(flags);
 139         preempt_disable();
 140         _raw_spin_lock_flags(lock, flags);
 141         return flags;
 142 }
 143 EXPORT_SYMBOL(_spin_lock_irqsave);
 144
 145 void __lockfunc _spin_lock_irq(spinlock_t *lock)
 146 {
 147         local_irq_disable();
 148         preempt_disable();
 149         _raw_spin_lock(lock);
 150 }
 151 EXPORT_SYMBOL(_spin_lock_irq);
 152
 153 void __lockfunc _spin_lock_bh(spinlock_t *lock)
 154 {
 155         local_bh_disable();
 156         preempt_disable();
 157         _raw_spin_lock(lock);
 158 }
 159 EXPORT_SYMBOL(_spin_lock_bh);
 160
 161 unsigned long __lockfunc _read_lock_irqsave(rwlock_t *lock)
 162 {
 163         unsigned long flags;
 164
 165         local_irq_save(flags);
 166         preempt_disable();
 167         _raw_read_lock(lock);
 168         return flags;
 169 }
 170 EXPORT_SYMBOL(_read_lock_irqsave);
 171
 172 void __lockfunc _read_lock_irq(rwlock_t *lock)
 173 {
 174         local_irq_disable();
 175         preempt_disable();
 176         _raw_read_lock(lock);
 177 }
 178 EXPORT_SYMBOL(_read_lock_irq);
 179
 180 void __lockfunc _read_lock_bh(rwlock_t *lock)
 181 {
 182         local_bh_disable();
 183         preempt_disable();
 184         _raw_read_lock(lock);
 185 }
 186 EXPORT_SYMBOL(_read_lock_bh);
 187
 188 unsigned long __lockfunc _write_lock_irqsave(rwlock_t *lock)
 189 {
 190         unsigned long flags;
 191
 192         local_irq_save(flags);
 193         preempt_disable();
 194         _raw_write_lock(lock);
 195         return flags;
 196 }
 197 EXPORT_SYMBOL(_write_lock_irqsave);
 198
 199 void __lockfunc _write_lock_irq(rwlock_t *lock)
 200 {
 201         local_irq_disable();
 202         preempt_disable();
 203         _raw_write_lock(lock);
 204 }
 205 EXPORT_SYMBOL(_write_lock_irq);
 206
 207 void __lockfunc _write_lock_bh(rwlock_t *lock)
 208 {
 209         local_bh_disable();
 210         preempt_disable();
 211         _raw_write_lock(lock);
 212 }
 213 EXPORT_SYMBOL(_write_lock_bh);
 214
 215 void __lockfunc _spin_unlock_irqrestore(spinlock_t *lock, unsigned long flags)
 216 {
 217         _raw_spin_unlock(lock);
 218         local_irq_restore(flags);
 219         preempt_enable();
 220 }
 221 EXPORT_SYMBOL(_spin_unlock_irqrestore);
 222
 223 void __lockfunc _spin_unlock_irq(spinlock_t *lock)
 224 {
 225         _raw_spin_unlock(lock);
 226         local_irq_enable();
 227         preempt_enable();
 228 }
 229 EXPORT_SYMBOL(_spin_unlock_irq);
 230
 231 void __lockfunc _spin_unlock_bh(spinlock_t *lock)
 232 {
 233         _raw_spin_unlock(lock);
 234         preempt_enable();
 235         local_bh_enable();
 236 }
 237 EXPORT_SYMBOL(_spin_unlock_bh);
 238
 239 void __lockfunc _read_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
 240 {
 241         _raw_read_unlock(lock);
 242         local_irq_restore(flags);
 243         preempt_enable();
 244 }
 245 EXPORT_SYMBOL(_read_unlock_irqrestore);
 246
 247 void __lockfunc _read_unlock_irq(rwlock_t *lock)
 248 {
 249         _raw_read_unlock(lock);
 250         local_irq_enable();
 251         preempt_enable();
 252 }
 253 EXPORT_SYMBOL(_read_unlock_irq);
 254
 255 void __lockfunc _read_unlock_bh(rwlock_t *lock)
 256 {
 257         _raw_read_unlock(lock);
 258         preempt_enable();
 259         local_bh_enable();
 260 }
 261 EXPORT_SYMBOL(_read_unlock_bh);
 262
 263 void __lockfunc _write_unlock_irqrestore(rwlock_t *lock, unsigned long flags)
 264 {
 265         _raw_write_unlock(lock);
 266         local_irq_restore(flags);
 267         preempt_enable();
 268 }
 269 EXPORT_SYMBOL(_write_unlock_irqrestore);
 270
 271 void __lockfunc _write_unlock_irq(rwlock_t *lock)
 272 {
 273         _raw_write_unlock(lock);
 274         local_irq_enable();
 275         preempt_enable();
 276 }
 277 EXPORT_SYMBOL(_write_unlock_irq);
 278
 279 void __lockfunc _write_unlock_bh(rwlock_t *lock)
 280 {
 281         _raw_write_unlock(lock);
 282         preempt_enable();
 283         local_bh_enable();
 284 }
 285 EXPORT_SYMBOL(_write_unlock_bh);
 286
 287 int __lockfunc _spin_trylock_bh(spinlock_t *lock)
 288 {
 289         local_bh_disable();
 290         preempt_disable();
 291         if (_raw_spin_trylock(lock))
 292                 return 1;
 293
 294         preempt_enable();
 295         local_bh_enable();
 296         return 0;
 297 }
 298 EXPORT_SYMBOL(_spin_trylock_bh);
 299
 300 int in_lock_functions(unsigned long addr)
 301 {
 302         /* Linker adds these: start and end of __lockfunc functions */
 303         extern char __lock_text_start[], __lock_text_end[];
 304
 305         return addr >= (unsigned long)__lock_text_start
 306         && addr < (unsigned long)__lock_text_end;
 307 }
 308 EXPORT_SYMBOL(in_lock_functions);