include/linux/spinlock_up.h

   1 #ifndef __LINUX_SPINLOCK_UP_H
   2 #define __LINUX_SPINLOCK_UP_H
   3
   4 #ifndef __LINUX_SPINLOCK_H
   5 # error "please don't include this file directly"
   6 #endif
   7
   8 /*
   9  * include/linux/spinlock_up.h - UP-debug version of spinlocks.
  10  *
  11  * portions Copyright 2005, Red Hat, Inc., Ingo Molnar
  12  * Released under the General Public License (GPL).
  13  *
  14  * In the debug case, 1 means unlocked, 0 means locked. (the values
  15  * are inverted, to catch initialization bugs)
  16  *
  17  * No atomicity anywhere, we are on UP.
  18  */
  19
  20 #ifdef CONFIG_DEBUG_SPINLOCK
  21 #define arch_spin_is_locked(x)          ((x)->slock == 0)
  22
  23 static inline void arch_spin_lock(arch_spinlock_t *lock)
  24 {
  25         lock->slock = 0;
  26 }
  27
  28 static inline void
  29 arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags)
  30 {
  31         local_irq_save(flags);
  32         lock->slock = 0;
  33 }
  34
  35 static inline int arch_spin_trylock(arch_spinlock_t *lock)
  36 {
  37         char oldval = lock->slock;
  38
  39         lock->slock = 0;
  40
  41         return oldval > 0;
  42 }
  43
  44 static inline void arch_spin_unlock(arch_spinlock_t *lock)
  45 {
  46         lock->slock = 1;
  47 }
  48
  49 /*
  50  * Read-write spinlocks. No debug version.
  51  */
  52 #define arch_read_lock(lock)            do { (void)(lock); } while (0)
  53 #define arch_write_lock(lock)           do { (void)(lock); } while (0)
  54 #define arch_read_trylock(lock) ({ (void)(lock); 1; })
  55 #define arch_write_trylock(lock)        ({ (void)(lock); 1; })
  56 #define arch_read_unlock(lock)          do { (void)(lock); } while (0)
  57 #define arch_write_unlock(lock) do { (void)(lock); } while (0)
  58
  59 #else /* DEBUG_SPINLOCK */
  60 #define arch_spin_is_locked(lock)       ((void)(lock), 0)
  61 /* for sched.c and kernel_lock.c: */
  62 # define arch_spin_lock(lock)           do { (void)(lock); } while (0)
  63 # define arch_spin_lock_flags(lock, flags)      do { (void)(lock); } while (0)
  64 # define arch_spin_unlock(lock) do { (void)(lock); } while (0)
  65 # define arch_spin_trylock(lock)        ({ (void)(lock); 1; })
  66 #endif /* DEBUG_SPINLOCK */
  67
  68 #define arch_spin_is_contended(lock)    (((void)(lock), 0))
  69
  70 #define arch_read_can_lock(lock)        (((void)(lock), 1))
  71 #define arch_write_can_lock(lock)       (((void)(lock), 1))
  72
  73 #define arch_spin_unlock_wait(lock) \
  74                 do { cpu_relax(); } while (arch_spin_is_locked(lock))
  75
  76 #endif /* __LINUX_SPINLOCK_UP_H */