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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 <asm/processor.h>
/*
* Your basic SMP spinlocks, allowing only a single CPU anywhere
*
* 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.
*
* (the type definitions are in asm/spinlock_types.h)
*/
static inline int __raw_spin_is_locked(raw_spinlock_t *lock)
{
return *(volatile signed int *)(&(lock)->slock) <= 0;
}
static inline void __raw_spin_lock(raw_spinlock_t *lock)
{
asm volatile(
"\n1:\t"
LOCK_PREFIX " ; decl %0\n\t"
"jns 2f\n"
"3:\n"
"rep;nop\n\t"
"cmpl $0,%0\n\t"
"jle 3b\n\t"
"jmp 1b\n"
"2:\t" : "=m" (lock->slock) : : "memory");
}
#define __raw_spin_lock_flags(lock, flags) __raw_spin_lock(lock)
static inline int __raw_spin_trylock(raw_spinlock_t *lock)
{
int oldval;
asm volatile(
"xchgl %0,%1"
:"=q" (oldval), "=m" (lock->slock)
:"0" (0) : "memory");
return oldval > 0;
}
static inline void __raw_spin_unlock(raw_spinlock_t *lock)
{
asm volatile("movl $1,%0" :"=m" (lock->slock) :: "memory");
}
static inline void __raw_spin_unlock_wait(raw_spinlock_t *lock)
{
while (__raw_spin_is_locked(lock))
cpu_relax();
}
/*
* 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.
*
* On x86, we implement read-write locks as a 32-bit counter
* with the high bit (sign) being the "contended" bit.
*/
static inline int __raw_read_can_lock(raw_rwlock_t *lock)
{
return (int)(lock)->lock > 0;
}
static inline int __raw_write_can_lock(raw_rwlock_t *lock)
{
return (lock)->lock == RW_LOCK_BIAS;
}
static inline void __raw_read_lock(raw_rwlock_t *rw)
{
asm volatile(LOCK_PREFIX "subl $1,(%0)\n\t"
"jns 1f\n"
"call __read_lock_failed\n"
"1:\n"
::"D" (rw), "i" (RW_LOCK_BIAS) : "memory");
}
static inline void __raw_write_lock(raw_rwlock_t *rw)
{
asm volatile(LOCK_PREFIX "subl %1,(%0)\n\t"
"jz 1f\n"
"\tcall __write_lock_failed\n\t"
"1:\n"
::"D" (rw), "i" (RW_LOCK_BIAS) : "memory");
}
static inline int __raw_read_trylock(raw_rwlock_t *lock)
{
atomic_t *count = (atomic_t *)lock;
atomic_dec(count);
if (atomic_read(count) >= 0)
return 1;
atomic_inc(count);
return 0;
}
static inline int __raw_write_trylock(raw_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;
}
static inline void __raw_read_unlock(raw_rwlock_t *rw)
{
asm volatile(LOCK_PREFIX " ; incl %0" :"=m" (rw->lock) : : "memory");
}
static inline void __raw_write_unlock(raw_rwlock_t *rw)
{
asm volatile(LOCK_PREFIX " ; addl $" RW_LOCK_BIAS_STR ",%0"
: "=m" (rw->lock) : : "memory");
}
#define _raw_spin_relax(lock) cpu_relax()
#define _raw_read_relax(lock) cpu_relax()
#define _raw_write_relax(lock) cpu_relax()
#endif /* __ASM_SPINLOCK_H */
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