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 #include <asm/processor.h>      /* for cpu_relax() */
   9
  10 /*
  11  * include/linux/spinlock_up.h - UP-debug version of spinlocks.
  12  *
  13  * portions Copyright 2005, Red Hat, Inc., Ingo Molnar
  14  * Released under the General Public License (GPL).
  15  *
  16  * In the debug case, 1 means unlocked, 0 means locked. (the values
  17  * are inverted, to catch initialization bugs)
  18  *
  19  * No atomicity anywhere, we are on UP.
  20  */
  21
  22 #ifdef CONFIG_DEBUG_SPINLOCK
  23 #define arch_spin_is_locked(x)          ((x)->slock == 0)
  24
  25 static inline void arch_spin_lock(arch_spinlock_t *lock)
  26 {
  27         lock->slock = 0;
  28 }
  29
  30 static inline void
  31 arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags)
  32 {
  33         local_irq_save(flags);
  34         lock->slock = 0;
  35 }
  36
  37 static inline int arch_spin_trylock(arch_spinlock_t *lock)
  38 {
  39         char oldval = lock->slock;
  40
  41         lock->slock = 0;
  42
  43         return oldval > 0;
  44 }
  45
  46 static inline void arch_spin_unlock(arch_spinlock_t *lock)
  47 {
  48         lock->slock = 1;
  49 }
  50
  51 /*
  52  * Read-write spinlocks. No debug version.
  53  */
  54 #define arch_read_lock(lock)            do { (void)(lock); } while (0)
  55 #define arch_write_lock(lock)           do { (void)(lock); } while (0)
  56 #define arch_read_trylock(lock) ({ (void)(lock); 1; })
  57 #define arch_write_trylock(lock)        ({ (void)(lock); 1; })
  58 #define arch_read_unlock(lock)          do { (void)(lock); } while (0)
  59 #define arch_write_unlock(lock) do { (void)(lock); } while (0)
  60
  61 #else /* DEBUG_SPINLOCK */
  62 #define arch_spin_is_locked(lock)       ((void)(lock), 0)
  63 /* for sched.c and kernel_lock.c: */
  64 # define arch_spin_lock(lock)           do { (void)(lock); } while (0)
  65 # define arch_spin_lock_flags(lock, flags)      do { (void)(lock); } while (0)
  66 # define arch_spin_unlock(lock) do { (void)(lock); } while (0)
  67 # define arch_spin_trylock(lock)        ({ (void)(lock); 1; })
  68 #endif /* DEBUG_SPINLOCK */
  69
  70 #define arch_spin_is_contended(lock)    (((void)(lock), 0))
  71
  72 #define arch_read_can_lock(lock)        (((void)(lock), 1))
  73 #define arch_write_can_lock(lock)       (((void)(lock), 1))
  74
  75 #define arch_spin_unlock_wait(lock) \
  76                 do { cpu_relax(); } while (arch_spin_is_locked(lock))
  77
  78 #endif /* __LINUX_SPINLOCK_UP_H */