1 #ifndef __ASM_SPINLOCK_H
2 #define __ASM_SPINLOCK_H
4 #include <asm/atomic.h>
5 #include <asm/rwlock.h>
7 #include <linux/config.h>
8 #include <linux/compiler.h>
10 asmlinkage int printk(const char * fmt, ...)
11 __attribute__ ((format (printf, 1, 2)));
14 * Your basic SMP spinlocks, allowing only a single CPU anywhere
18 volatile unsigned int lock;
19 #ifdef CONFIG_DEBUG_SPINLOCK
24 #define SPINLOCK_MAGIC 0xdead4ead
26 #ifdef CONFIG_DEBUG_SPINLOCK
27 #define SPINLOCK_MAGIC_INIT , SPINLOCK_MAGIC
29 #define SPINLOCK_MAGIC_INIT /* */
32 #define SPIN_LOCK_UNLOCKED (spinlock_t) { 1 SPINLOCK_MAGIC_INIT }
34 #define spin_lock_init(x) do { *(x) = SPIN_LOCK_UNLOCKED; } while(0)
37 * Simple spin lock operations. There are two variants, one clears IRQ's
38 * on the local processor, one does not.
40 * We make no fairness assumptions. They have a cost.
43 #define spin_is_locked(x) (*(volatile signed char *)(&(x)->lock) <= 0)
44 #define spin_unlock_wait(x) do { barrier(); } while(spin_is_locked(x))
46 #define spin_lock_string \
48 "lock ; decb %0\n\t" \
57 #define spin_lock_string_flags \
59 "lock ; decb %0\n\t" \
62 "testl $0x200, %1\n\t" \
74 * This works. Despite all the confusion.
75 * (except on PPro SMP or if we are using OOSTORE)
76 * (PPro errata 66, 92)
79 #if !defined(CONFIG_X86_OOSTORE) && !defined(CONFIG_X86_PPRO_FENCE)
81 #define spin_unlock_string \
83 :"=m" (lock->lock) : : "memory"
86 static inline void _raw_spin_unlock(spinlock_t *lock)
88 #ifdef CONFIG_DEBUG_SPINLOCK
89 BUG_ON(lock->magic != SPINLOCK_MAGIC);
90 BUG_ON(!spin_is_locked(lock));
99 #define spin_unlock_string \
101 :"=q" (oldval), "=m" (lock->lock) \
102 :"0" (oldval) : "memory"
104 static inline void _raw_spin_unlock(spinlock_t *lock)
107 #ifdef CONFIG_DEBUG_SPINLOCK
108 BUG_ON(lock->magic != SPINLOCK_MAGIC);
109 BUG_ON(!spin_is_locked(lock));
111 __asm__ __volatile__(
118 static inline int _raw_spin_trylock(spinlock_t *lock)
121 __asm__ __volatile__(
123 :"=q" (oldval), "=m" (lock->lock)
124 :"0" (0) : "memory");
128 static inline void _raw_spin_lock(spinlock_t *lock)
130 #ifdef CONFIG_DEBUG_SPINLOCK
131 if (unlikely(lock->magic != SPINLOCK_MAGIC)) {
132 printk("eip: %p\n", __builtin_return_address(0));
136 __asm__ __volatile__(
138 :"=m" (lock->lock) : : "memory");
141 static inline void _raw_spin_lock_flags (spinlock_t *lock, unsigned long flags)
143 #ifdef CONFIG_DEBUG_SPINLOCK
144 if (unlikely(lock->magic != SPINLOCK_MAGIC)) {
145 printk("eip: %p\n", __builtin_return_address(0));
149 __asm__ __volatile__(
150 spin_lock_string_flags
151 :"=m" (lock->lock) : "r" (flags) : "memory");
155 * Read-write spinlocks, allowing multiple readers
156 * but only one writer.
158 * NOTE! it is quite common to have readers in interrupts
159 * but no interrupt writers. For those circumstances we
160 * can "mix" irq-safe locks - any writer needs to get a
161 * irq-safe write-lock, but readers can get non-irqsafe
165 volatile unsigned int lock;
166 #ifdef CONFIG_DEBUG_SPINLOCK
171 #define RWLOCK_MAGIC 0xdeaf1eed
173 #ifdef CONFIG_DEBUG_SPINLOCK
174 #define RWLOCK_MAGIC_INIT , RWLOCK_MAGIC
176 #define RWLOCK_MAGIC_INIT /* */
179 #define RW_LOCK_UNLOCKED (rwlock_t) { RW_LOCK_BIAS RWLOCK_MAGIC_INIT }
181 #define rwlock_init(x) do { *(x) = RW_LOCK_UNLOCKED; } while(0)
183 #define rwlock_is_locked(x) ((x)->lock != RW_LOCK_BIAS)
186 * On x86, we implement read-write locks as a 32-bit counter
187 * with the high bit (sign) being the "contended" bit.
189 * The inline assembly is non-obvious. Think about it.
191 * Changed to use the same technique as rw semaphores. See
192 * semaphore.h for details. -ben
194 /* the spinlock helpers are in arch/i386/kernel/semaphore.c */
196 static inline void _raw_read_lock(rwlock_t *rw)
198 #ifdef CONFIG_DEBUG_SPINLOCK
199 BUG_ON(rw->magic != RWLOCK_MAGIC);
201 __build_read_lock(rw, "__read_lock_failed");
204 static inline void _raw_write_lock(rwlock_t *rw)
206 #ifdef CONFIG_DEBUG_SPINLOCK
207 BUG_ON(rw->magic != RWLOCK_MAGIC);
209 __build_write_lock(rw, "__write_lock_failed");
212 #define _raw_read_unlock(rw) asm volatile("lock ; incl %0" :"=m" ((rw)->lock) : : "memory")
213 #define _raw_write_unlock(rw) asm volatile("lock ; addl $" RW_LOCK_BIAS_STR ",%0":"=m" ((rw)->lock) : : "memory")
215 static inline int _raw_write_trylock(rwlock_t *lock)
217 atomic_t *count = (atomic_t *)lock;
218 if (atomic_sub_and_test(RW_LOCK_BIAS, count))
220 atomic_add(RW_LOCK_BIAS, count);
224 #endif /* __ASM_SPINLOCK_H */