Edit File: spinlock_up.h
#ifndef __LINUX_SPINLOCK_UP_H #define __LINUX_SPINLOCK_UP_H #ifndef __LINUX_SPINLOCK_H # error "please don't include this file directly" #endif #include <asm/processor.h> /* for cpu_relax() */ /* * include/linux/spinlock_up.h - UP-debug version of spinlocks. * * portions Copyright 2005, Red Hat, Inc., Ingo Molnar * Released under the General Public License (GPL). * * In the debug case, 1 means unlocked, 0 means locked. (the values * are inverted, to catch initialization bugs) * * No atomicity anywhere, we are on UP. However, we still need * the compiler barriers, because we do not want the compiler to * move potentially faulting instructions (notably user accesses) * into the locked sequence, resulting in non-atomic execution. */ #ifdef CONFIG_DEBUG_SPINLOCK #define arch_spin_is_locked(x) ((x)->slock == 0) static inline void arch_spin_lock(arch_spinlock_t *lock) { lock->slock = 0; barrier(); } static inline void arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags) { local_irq_save(flags); lock->slock = 0; barrier(); } static inline int arch_spin_trylock(arch_spinlock_t *lock) { char oldval = lock->slock; lock->slock = 0; barrier(); return oldval > 0; } static inline void arch_spin_unlock(arch_spinlock_t *lock) { barrier(); lock->slock = 1; } /* * Read-write spinlocks. No debug version. */ #define arch_read_lock(lock) do { barrier(); (void)(lock); } while (0) #define arch_write_lock(lock) do { barrier(); (void)(lock); } while (0) #define arch_read_trylock(lock) ({ barrier(); (void)(lock); 1; }) #define arch_write_trylock(lock) ({ barrier(); (void)(lock); 1; }) #define arch_read_unlock(lock) do { barrier(); (void)(lock); } while (0) #define arch_write_unlock(lock) do { barrier(); (void)(lock); } while (0) #else /* DEBUG_SPINLOCK */ #define arch_spin_is_locked(lock) ((void)(lock), 0) /* for sched.c and kernel_lock.c: */ # define arch_spin_lock(lock) do { barrier(); (void)(lock); } while (0) # define arch_spin_lock_flags(lock, flags) do { barrier(); (void)(lock); } while (0) # define arch_spin_unlock(lock) do { barrier(); (void)(lock); } while (0) # define arch_spin_trylock(lock) ({ barrier(); (void)(lock); 1; }) #endif /* DEBUG_SPINLOCK */ #define arch_spin_is_contended(lock) (((void)(lock), 0)) #define arch_read_can_lock(lock) (((void)(lock), 1)) #define arch_write_can_lock(lock) (((void)(lock), 1)) #define arch_spin_unlock_wait(lock) \ do { cpu_relax(); } while (arch_spin_is_locked(lock)) #endif /* __LINUX_SPINLOCK_UP_H */