199 lines
4.3 KiB
C
199 lines
4.3 KiB
C
#ifndef __ASM_SPINLOCK_H
|
|
#define __ASM_SPINLOCK_H
|
|
|
|
#include <asm/atomic.h>
|
|
#include <asm/rwlock.h>
|
|
#include <asm/page.h>
|
|
#include <linux/compiler.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)
|
|
*/
|
|
|
|
#define __raw_spin_is_locked(x) \
|
|
(*(volatile signed char *)(&(x)->slock) <= 0)
|
|
|
|
#define __raw_spin_lock_string \
|
|
"\n1:\t" \
|
|
"lock ; decb %0\n\t" \
|
|
"jns 3f\n" \
|
|
"2:\t" \
|
|
"rep;nop\n\t" \
|
|
"cmpb $0,%0\n\t" \
|
|
"jle 2b\n\t" \
|
|
"jmp 1b\n" \
|
|
"3:\n\t"
|
|
|
|
#define __raw_spin_lock_string_flags \
|
|
"\n1:\t" \
|
|
"lock ; decb %0\n\t" \
|
|
"jns 5f\n" \
|
|
"2:\t" \
|
|
"testl $0x200, %1\n\t" \
|
|
"jz 4f\n\t" \
|
|
"sti\n" \
|
|
"3:\t" \
|
|
"rep;nop\n\t" \
|
|
"cmpb $0, %0\n\t" \
|
|
"jle 3b\n\t" \
|
|
"cli\n\t" \
|
|
"jmp 1b\n" \
|
|
"4:\t" \
|
|
"rep;nop\n\t" \
|
|
"cmpb $0, %0\n\t" \
|
|
"jg 1b\n\t" \
|
|
"jmp 4b\n" \
|
|
"5:\n\t"
|
|
|
|
#define __raw_spin_lock_string_up \
|
|
"\n\tdecb %0"
|
|
|
|
static inline void __raw_spin_lock(raw_spinlock_t *lock)
|
|
{
|
|
alternative_smp(
|
|
__raw_spin_lock_string,
|
|
__raw_spin_lock_string_up,
|
|
"=m" (lock->slock) : : "memory");
|
|
}
|
|
|
|
static inline void __raw_spin_lock_flags(raw_spinlock_t *lock, unsigned long flags)
|
|
{
|
|
alternative_smp(
|
|
__raw_spin_lock_string_flags,
|
|
__raw_spin_lock_string_up,
|
|
"=m" (lock->slock) : "r" (flags) : "memory");
|
|
}
|
|
|
|
static inline int __raw_spin_trylock(raw_spinlock_t *lock)
|
|
{
|
|
char oldval;
|
|
__asm__ __volatile__(
|
|
"xchgb %b0,%1"
|
|
:"=q" (oldval), "=m" (lock->slock)
|
|
:"0" (0) : "memory");
|
|
return oldval > 0;
|
|
}
|
|
|
|
/*
|
|
* __raw_spin_unlock based on writing $1 to the low byte.
|
|
* This method works. Despite all the confusion.
|
|
* (except on PPro SMP or if we are using OOSTORE, so we use xchgb there)
|
|
* (PPro errata 66, 92)
|
|
*/
|
|
|
|
#if !defined(CONFIG_X86_OOSTORE) && !defined(CONFIG_X86_PPRO_FENCE)
|
|
|
|
#define __raw_spin_unlock_string \
|
|
"movb $1,%0" \
|
|
:"=m" (lock->slock) : : "memory"
|
|
|
|
|
|
static inline void __raw_spin_unlock(raw_spinlock_t *lock)
|
|
{
|
|
__asm__ __volatile__(
|
|
__raw_spin_unlock_string
|
|
);
|
|
}
|
|
|
|
#else
|
|
|
|
#define __raw_spin_unlock_string \
|
|
"xchgb %b0, %1" \
|
|
:"=q" (oldval), "=m" (lock->slock) \
|
|
:"0" (oldval) : "memory"
|
|
|
|
static inline void __raw_spin_unlock(raw_spinlock_t *lock)
|
|
{
|
|
char oldval = 1;
|
|
|
|
__asm__ __volatile__(
|
|
__raw_spin_unlock_string
|
|
);
|
|
}
|
|
|
|
#endif
|
|
|
|
#define __raw_spin_unlock_wait(lock) \
|
|
do { while (__raw_spin_is_locked(lock)) cpu_relax(); } while (0)
|
|
|
|
/*
|
|
* 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.
|
|
*
|
|
* 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 helpers are in arch/i386/kernel/semaphore.c
|
|
*/
|
|
|
|
/**
|
|
* read_can_lock - would read_trylock() succeed?
|
|
* @lock: the rwlock in question.
|
|
*/
|
|
#define __raw_read_can_lock(x) ((int)(x)->lock > 0)
|
|
|
|
/**
|
|
* write_can_lock - would write_trylock() succeed?
|
|
* @lock: the rwlock in question.
|
|
*/
|
|
#define __raw_write_can_lock(x) ((x)->lock == RW_LOCK_BIAS)
|
|
|
|
static inline void __raw_read_lock(raw_rwlock_t *rw)
|
|
{
|
|
__build_read_lock(rw, "__read_lock_failed");
|
|
}
|
|
|
|
static inline void __raw_write_lock(raw_rwlock_t *rw)
|
|
{
|
|
__build_write_lock(rw, "__write_lock_failed");
|
|
}
|
|
|
|
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");
|
|
}
|
|
|
|
#endif /* __ASM_SPINLOCK_H */
|