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. However, we still need 20 * the compiler barriers, because we do not want the compiler to 21 * move potentially faulting instructions (notably user accesses) 22 * into the locked sequence, resulting in non-atomic execution. 23 */ 24 25 #ifdef CONFIG_DEBUG_SPINLOCK 26 #define arch_spin_is_locked(x) ((x)->slock == 0) 27 28 static inline void arch_spin_lock(arch_spinlock_t *lock) 29 { 30 lock->slock = 0; 31 barrier(); 32 } 33 34 static inline void 35 arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags) 36 { 37 local_irq_save(flags); 38 lock->slock = 0; 39 barrier(); 40 } 41 42 static inline int arch_spin_trylock(arch_spinlock_t *lock) 43 { 44 char oldval = lock->slock; 45 46 lock->slock = 0; 47 barrier(); 48 49 return oldval > 0; 50 } 51 52 static inline void arch_spin_unlock(arch_spinlock_t *lock) 53 { 54 barrier(); 55 lock->slock = 1; 56 } 57 58 /* 59 * Read-write spinlocks. No debug version. 60 */ 61 #define arch_read_lock(lock) do { barrier(); (void)(lock); } while (0) 62 #define arch_write_lock(lock) do { barrier(); (void)(lock); } while (0) 63 #define arch_read_trylock(lock) ({ barrier(); (void)(lock); 1; }) 64 #define arch_write_trylock(lock) ({ barrier(); (void)(lock); 1; }) 65 #define arch_read_unlock(lock) do { barrier(); (void)(lock); } while (0) 66 #define arch_write_unlock(lock) do { barrier(); (void)(lock); } while (0) 67 68 #else /* DEBUG_SPINLOCK */ 69 #define arch_spin_is_locked(lock) ((void)(lock), 0) 70 /* for sched/core.c and kernel_lock.c: */ 71 # define arch_spin_lock(lock) do { barrier(); (void)(lock); } while (0) 72 # define arch_spin_lock_flags(lock, flags) do { barrier(); (void)(lock); } while (0) 73 # define arch_spin_unlock(lock) do { barrier(); (void)(lock); } while (0) 74 # define arch_spin_trylock(lock) ({ barrier(); (void)(lock); 1; }) 75 #endif /* DEBUG_SPINLOCK */ 76 77 #define arch_spin_is_contended(lock) (((void)(lock), 0)) 78 79 #define arch_read_can_lock(lock) (((void)(lock), 1)) 80 #define arch_write_can_lock(lock) (((void)(lock), 1)) 81 82 #define arch_spin_unlock_wait(lock) \ 83 do { cpu_relax(); } while (arch_spin_is_locked(lock)) 84 85 #endif /* __LINUX_SPINLOCK_UP_H */ 86