| #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 <asm/barrier.h> |
| |
| /* |
| * 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 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/core.c and kernel_lock.c: */ |
| # define arch_spin_lock(lock) 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)) |
| |
| #endif /* __LINUX_SPINLOCK_UP_H */ |