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#ifndef __ASM_SPINLOCK_H

#define __ASM_SPINLOCK_H

#include <asm/atomic.h>

#include <asm/rwlock.h>

#include <asm/page.h>

#include <linux/kernel.h>

#include <linux/config.h>

extern int printk(const char * fmt, ...)

        __attribute__ ((format (printf, 1, 2)));

/* It seems that people are forgetting to

 * initialize their spinlocks properly, tsk tsk.

 * Remember to turn this off in 2.4. -ben

 */

#if defined(CONFIG_DEBUG_SPINLOCK)

#define SPINLOCK_DEBUG  1

#else

#define SPINLOCK_DEBUG  0

#endif

/*

 * Your basic SMP spinlocks, allowing only a single CPU anywhere

 */

typedef struct {

        volatile unsigned int lock;

#if SPINLOCK_DEBUG

        unsigned magic;

#endif

} spinlock_t;

#define SPINLOCK_MAGIC  0xdead4ead

#if SPINLOCK_DEBUG

#define SPINLOCK_MAGIC_INIT     , SPINLOCK_MAGIC

#else

#define SPINLOCK_MAGIC_INIT     /* */

#endif

#define SPIN_LOCK_UNLOCKED (spinlock_t) { 1 SPINLOCK_MAGIC_INIT }

#define spin_lock_init(x)       do { *(x) = SPIN_LOCK_UNLOCKED; } while(0)

/*

 * Simple spin lock operations.  There are two variants, one clears IRQ's

 * on the local processor, one does not.

 *

 * We make no fairness assumptions. They have a cost.

 */

#define spin_is_locked(x)       (*(volatile signed char *)(&(x)->lock) <= 0)

#define spin_unlock_wait(x)     do { barrier(); } while(spin_is_locked(x))

#define spin_lock_string \

        "\n1:\t" \

        "lock ; decb %0\n\t" \

        "js 2f\n" \

        LOCK_SECTION_START("") \

        "2:\t" \

        "cmpb $0,%0\n\t" \

        "rep;nop\n\t" \

        "jle 2b\n\t" \

        "jmp 1b\n" \

        LOCK_SECTION_END

/*

 * This works. Despite all the confusion.

 */

#define spin_unlock_string \

        "movb $1,%0"

static inline int spin_trylock(spinlock_t *lock)

{

        char oldval;

        __asm__ __volatile__(

                "xchgb %b0,%1"

                :"=q" (oldval), "=m" (lock->lock)

                :"0" (0) : "memory");

        return oldval > 0;

}

static inline void spin_lock(spinlock_t *lock)

{

#if SPINLOCK_DEBUG

        __label__ here;

here:

        if (lock->magic != SPINLOCK_MAGIC) {

printk("eip: %p\n", &&here);

                out_of_line_bug();

        }

#endif

        __asm__ __volatile__(

                spin_lock_string

                :"=m" (lock->lock) : : "memory");

}

static inline void spin_unlock(spinlock_t *lock)

{

#if SPINLOCK_DEBUG

        if (lock->magic != SPINLOCK_MAGIC)

                out_of_line_bug();

        if (!spin_is_locked(lock))

                out_of_line_bug();

#endif

        __asm__ __volatile__(

                spin_unlock_string

                :"=m" (lock->lock) : : "memory");

}

/*

 * Read-write spinlocks, allowing multiple readers

 * but only one writer.

 *

 * NOTE! it is quite common to have readers in interrupts

 * but no interrupt writers. For those circumstances we

 * can "mix" irq-safe locks - any writer needs to get a

 * irq-safe write-lock, but readers can get non-irqsafe

 * read-locks.

 */

typedef struct {

        volatile unsigned int lock;

#if SPINLOCK_DEBUG

        unsigned magic;

#endif

} rwlock_t;

#define RWLOCK_MAGIC    0xdeaf1eed

#if SPINLOCK_DEBUG

#define RWLOCK_MAGIC_INIT       , RWLOCK_MAGIC

#else

#define RWLOCK_MAGIC_INIT       /* */

#endif

#define RW_LOCK_UNLOCKED (rwlock_t) { RW_LOCK_BIAS RWLOCK_MAGIC_INIT }

#define rwlock_init(x)  do { *(x) = RW_LOCK_UNLOCKED; } while(0)

/*

 * On x86, we implement read-write locks as a 32-bit counter

 * with the high bit (sign) being the "contended" bit.

 *

 * The inline assembly is non-obvious. Think about it.

 *

 * Changed to use the same technique as rw semaphores.  See

 * semaphore.h for details.  -ben

 */

/* the spinlock helpers are in arch/x86_64/kernel/semaphore.S */

extern inline void read_lock(rwlock_t *rw)

{

#if SPINLOCK_DEBUG

        if (rw->magic != RWLOCK_MAGIC)

                out_of_line_bug();

#endif

        __build_read_lock(rw, "__read_lock_failed");

}

static inline void write_lock(rwlock_t *rw)

{

#if SPINLOCK_DEBUG

        if (rw->magic != RWLOCK_MAGIC)

                out_of_line_bug();

#endif

        __build_write_lock(rw, "__write_lock_failed");

}

#define read_unlock(rw)         asm volatile("lock ; incl %0" :"=m" ((rw)->lock) : : "memory")

#define write_unlock(rw)        asm volatile("lock ; addl $" RW_LOCK_BIAS_STR ",%0":"=m" ((rw)->lock) : : "memory")

static inline int write_trylock(rwlock_t *lock)

{

        atomic_t *count = (atomic_t *)lock;

        if (atomic_sub_and_test(RW_LOCK_BIAS, count))

                return 1;

        atomic_add(RW_LOCK_BIAS, count);

        return 0;

}

#endif /* __ASM_SPINLOCK_H */