local.h

来自「linux 内核源代码」· C头文件 代码 · 共 222 行

#ifndef _ARCH_MIPS_LOCAL_H
#define _ARCH_MIPS_LOCAL_H

#include <linux/percpu.h>
#include <linux/bitops.h>
#include <asm/atomic.h>
#include <asm/cmpxchg.h>
#include <asm/war.h>

typedef struct
{
	atomic_long_t a;
} local_t;

#define LOCAL_INIT(i)	{ ATOMIC_LONG_INIT(i) }

#define local_read(l)	atomic_long_read(&(l)->a)
#define local_set(l, i)	atomic_long_set(&(l)->a, (i))

#define local_add(i, l)	atomic_long_add((i), (&(l)->a))
#define local_sub(i, l)	atomic_long_sub((i), (&(l)->a))
#define local_inc(l)	atomic_long_inc(&(l)->a)
#define local_dec(l)	atomic_long_dec(&(l)->a)

/*
 * Same as above, but return the result value
 */
static __inline__ long local_add_return(long i, local_t * l)
{
	unsigned long result;

	if (cpu_has_llsc && R10000_LLSC_WAR) {
		unsigned long temp;

		__asm__ __volatile__(
		"	.set	mips3					\n"
		"1:"	__LL	"%1, %2		# local_add_return	\n"
		"	addu	%0, %1, %3				\n"
			__SC	"%0, %2					\n"
		"	beqzl	%0, 1b					\n"
		"	addu	%0, %1, %3				\n"
		"	.set	mips0					\n"
		: "=&r" (result), "=&r" (temp), "=m" (l->a.counter)
		: "Ir" (i), "m" (l->a.counter)
		: "memory");
	} else if (cpu_has_llsc) {
		unsigned long temp;

		__asm__ __volatile__(
		"	.set	mips3					\n"
		"1:"	__LL	"%1, %2		# local_add_return	\n"
		"	addu	%0, %1, %3				\n"
			__SC	"%0, %2					\n"
		"	beqz	%0, 1b					\n"
		"	addu	%0, %1, %3				\n"
		"	.set	mips0					\n"
		: "=&r" (result), "=&r" (temp), "=m" (l->a.counter)
		: "Ir" (i), "m" (l->a.counter)
		: "memory");
	} else {
		unsigned long flags;

		local_irq_save(flags);
		result = l->a.counter;
		result += i;
		l->a.counter = result;
		local_irq_restore(flags);
	}

	return result;
}

static __inline__ long local_sub_return(long i, local_t * l)
{
	unsigned long result;

	if (cpu_has_llsc && R10000_LLSC_WAR) {
		unsigned long temp;

		__asm__ __volatile__(
		"	.set	mips3					\n"
		"1:"	__LL	"%1, %2		# local_sub_return	\n"
		"	subu	%0, %1, %3				\n"
			__SC	"%0, %2					\n"
		"	beqzl	%0, 1b					\n"
		"	subu	%0, %1, %3				\n"
		"	.set	mips0					\n"
		: "=&r" (result), "=&r" (temp), "=m" (l->a.counter)
		: "Ir" (i), "m" (l->a.counter)
		: "memory");
	} else if (cpu_has_llsc) {
		unsigned long temp;

		__asm__ __volatile__(
		"	.set	mips3					\n"
		"1:"	__LL	"%1, %2		# local_sub_return	\n"
		"	subu	%0, %1, %3				\n"
			__SC	"%0, %2					\n"
		"	beqz	%0, 1b					\n"
		"	subu	%0, %1, %3				\n"
		"	.set	mips0					\n"
		: "=&r" (result), "=&r" (temp), "=m" (l->a.counter)
		: "Ir" (i), "m" (l->a.counter)
		: "memory");
	} else {
		unsigned long flags;

		local_irq_save(flags);
		result = l->a.counter;
		result -= i;
		l->a.counter = result;
		local_irq_restore(flags);
	}

	return result;
}

#define local_cmpxchg(l, o, n) \
	((long)cmpxchg_local(&((l)->a.counter), (o), (n)))
#define local_xchg(l, n) (xchg_local(&((l)->a.counter), (n)))

/**
 * local_add_unless - add unless the number is a given value
 * @l: pointer of type local_t
 * @a: the amount to add to l...
 * @u: ...unless l is equal to u.
 *
 * Atomically adds @a to @l, so long as it was not @u.
 * Returns non-zero if @l was not @u, and zero otherwise.
 */
#define local_add_unless(l, a, u)				\
({								\
	long c, old;						\
	c = local_read(l);					\
	while (c != (u) && (old = local_cmpxchg((l), c, c + (a))) != c) \
		c = old;					\
	c != (u);						\
})
#define local_inc_not_zero(l) local_add_unless((l), 1, 0)

#define local_dec_return(l) local_sub_return(1, (l))
#define local_inc_return(l) local_add_return(1, (l))

/*
 * local_sub_and_test - subtract value from variable and test result
 * @i: integer value to subtract
 * @l: pointer of type local_t
 *
 * Atomically subtracts @i from @l and returns
 * true if the result is zero, or false for all
 * other cases.
 */
#define local_sub_and_test(i, l) (local_sub_return((i), (l)) == 0)

/*
 * local_inc_and_test - increment and test
 * @l: pointer of type local_t
 *
 * Atomically increments @l by 1
 * and returns true if the result is zero, or false for all
 * other cases.
 */
#define local_inc_and_test(l) (local_inc_return(l) == 0)

/*
 * local_dec_and_test - decrement by 1 and test
 * @l: pointer of type local_t
 *
 * Atomically decrements @l by 1 and
 * returns true if the result is 0, or false for all other
 * cases.
 */
#define local_dec_and_test(l) (local_sub_return(1, (l)) == 0)

/*
 * local_add_negative - add and test if negative
 * @l: pointer of type local_t
 * @i: integer value to add
 *
 * Atomically adds @i to @l and returns true
 * if the result is negative, or false when
 * result is greater than or equal to zero.
 */
#define local_add_negative(i, l) (local_add_return(i, (l)) < 0)

/* Use these for per-cpu local_t variables: on some archs they are
 * much more efficient than these naive implementations.  Note they take
 * a variable, not an address.
 */

#define __local_inc(l)		((l)->a.counter++)
#define __local_dec(l)		((l)->a.counter++)
#define __local_add(i, l)	((l)->a.counter+=(i))
#define __local_sub(i, l)	((l)->a.counter-=(i))

/* Need to disable preemption for the cpu local counters otherwise we could
   still access a variable of a previous CPU in a non atomic way. */
#define cpu_local_wrap_v(l)	 	\
	({ local_t res__;		\
	   preempt_disable(); 		\
	   res__ = (l);			\
	   preempt_enable();		\
	   res__; })
#define cpu_local_wrap(l)		\
	({ preempt_disable();		\
	   l;				\
	   preempt_enable(); })		\

#define cpu_local_read(l)    cpu_local_wrap_v(local_read(&__get_cpu_var(l)))
#define cpu_local_set(l, i)  cpu_local_wrap(local_set(&__get_cpu_var(l), (i)))
#define cpu_local_inc(l)     cpu_local_wrap(local_inc(&__get_cpu_var(l)))
#define cpu_local_dec(l)     cpu_local_wrap(local_dec(&__get_cpu_var(l)))
#define cpu_local_add(i, l)  cpu_local_wrap(local_add((i), &__get_cpu_var(l)))
#define cpu_local_sub(i, l)  cpu_local_wrap(local_sub((i), &__get_cpu_var(l)))

#define __cpu_local_inc(l)	cpu_local_inc(l)
#define __cpu_local_dec(l)	cpu_local_dec(l)
#define __cpu_local_add(i, l)	cpu_local_add((i), (l))
#define __cpu_local_sub(i, l)	cpu_local_sub((i), (l))

#endif /* _ARCH_MIPS_LOCAL_H */