1 #ifndef __LINUX_SPINLOCK_UP_H 2 #define __LINUX_SPINLOCK_UP_H 3 4 #ifndef __LINUX_INSIDE_SPINLOCK_H 5 # error "please don't include this file directly" 6 #endif 7 8 #include <asm/processor.h> /* for cpu_relax() */ 9 #include <asm/barrier.h> 10 11 /* 12 * include/linux/spinlock_up.h - UP-debug version of spinlocks. 13 * 14 * portions Copyright 2005, Red Hat, Inc., Ingo Molnar 15 * Released under the General Public License (GPL). 16 * 17 * In the debug case, 1 means unlocked, 0 means locked. (the values 18 * are inverted, to catch initialization bugs) 19 * 20 * No atomicity anywhere, we are on UP. However, we still need 21 * the compiler barriers, because we do not want the compiler to 22 * move potentially faulting instructions (notably user accesses) 23 * into the locked sequence, resulting in non-atomic execution. 24 */ 25 26 #ifdef CONFIG_DEBUG_SPINLOCK 27 #define arch_spin_is_locked(x) ((x)->slock == 0) 28 29 static inline void arch_spin_lock(arch_spinlock_t *lock) 30 { 31 lock->slock = 0; 32 barrier(); 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 barrier(); 41 42 return oldval > 0; 43 } 44 45 static inline void arch_spin_unlock(arch_spinlock_t *lock) 46 { 47 barrier(); 48 lock->slock = 1; 49 } 50 51 /* 52 * Read-write spinlocks. No debug version. 53 */ 54 #define arch_read_lock(lock) do { barrier(); (void)(lock); } while (0) 55 #define arch_write_lock(lock) do { barrier(); (void)(lock); } while (0) 56 #define arch_read_trylock(lock) ({ barrier(); (void)(lock); 1; }) 57 #define arch_write_trylock(lock) ({ barrier(); (void)(lock); 1; }) 58 #define arch_read_unlock(lock) do { barrier(); (void)(lock); } while (0) 59 #define arch_write_unlock(lock) do { barrier(); (void)(lock); } while (0) 60 61 #else /* DEBUG_SPINLOCK */ 62 #define arch_spin_is_locked(lock) ((void)(lock), 0) 63 /* for sched/core.c and kernel_lock.c: */ 64 # define arch_spin_lock(lock) do { barrier(); (void)(lock); } while (0) 65 # define arch_spin_unlock(lock) do { barrier(); (void)(lock); } while (0) 66 # define arch_spin_trylock(lock) ({ barrier(); (void)(lock); 1; }) 67 #endif /* DEBUG_SPINLOCK */ 68 69 #define arch_spin_is_contended(lock) (((void)(lock), 0)) 70 71 #endif /* __LINUX_SPINLOCK_UP_H */ 72