| 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 */ |