arch/parisc/include/asm/atomic.h

Source file repositories/reference/linux-study-clean/arch/parisc/include/asm/atomic.h

File Facts

System
Linux kernel
Corpus path
arch/parisc/include/asm/atomic.h
Extension
.h
Size
6110 bytes
Lines
239
Domain
Architecture Layer
Bucket
arch/parisc
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

#ifndef _ASM_PARISC_ATOMIC_H_
#define _ASM_PARISC_ATOMIC_H_

#include <linux/types.h>
#include <asm/cmpxchg.h>
#include <asm/barrier.h>

/*
 * Atomic operations that C can't guarantee us.  Useful for
 * resource counting etc..
 *
 * And probably incredibly slow on parisc.  OTOH, we don't
 * have to write any serious assembly.   prumpf
 */

#ifdef CONFIG_SMP
#include <asm/spinlock.h>
#include <asm/cache.h>		/* we use L1_CACHE_BYTES */

/* Use an array of spinlocks for our atomic_ts.
 * Hash function to index into a different SPINLOCK.
 * Since "a" is usually an address, use one spinlock per cacheline.
 */
#  define ATOMIC_HASH_SIZE 4
#  define ATOMIC_HASH(a) (&(__atomic_hash[ (((unsigned long) (a))/L1_CACHE_BYTES) & (ATOMIC_HASH_SIZE-1) ]))

extern arch_spinlock_t __atomic_hash[ATOMIC_HASH_SIZE] __lock_aligned;

/* Can't use raw_spin_lock_irq because of #include problems, so
 * this is the substitute */
#define _atomic_spin_lock_irqsave(l,f) do {	\
	arch_spinlock_t *s = ATOMIC_HASH(l);	\
	local_irq_save(f);			\
	arch_spin_lock(s);			\
} while(0)

#define _atomic_spin_unlock_irqrestore(l,f) do {	\
	arch_spinlock_t *s = ATOMIC_HASH(l);		\
	arch_spin_unlock(s);				\
	local_irq_restore(f);				\
} while(0)


#else
#  define _atomic_spin_lock_irqsave(l,f) do { local_irq_save(f); } while (0)
#  define _atomic_spin_unlock_irqrestore(l,f) do { local_irq_restore(f); } while (0)
#endif

/*
 * Note that we need not lock read accesses - aligned word writes/reads
 * are atomic, so a reader never sees inconsistent values.
 */

static __inline__ void arch_atomic_set(atomic_t *v, int i)
{
	unsigned long flags;
	_atomic_spin_lock_irqsave(v, flags);

	v->counter = i;

	_atomic_spin_unlock_irqrestore(v, flags);
}

#define arch_atomic_set_release(v, i)	arch_atomic_set((v), (i))

static __inline__ int arch_atomic_read(const atomic_t *v)
{
	return READ_ONCE((v)->counter);
}

#define ATOMIC_OP(op, c_op)						\
static __inline__ void arch_atomic_##op(int i, atomic_t *v)		\
{									\
	unsigned long flags;						\
									\
	_atomic_spin_lock_irqsave(v, flags);				\
	v->counter c_op i;						\
	_atomic_spin_unlock_irqrestore(v, flags);			\
}

#define ATOMIC_OP_RETURN(op, c_op)					\
static __inline__ int arch_atomic_##op##_return(int i, atomic_t *v)	\
{									\
	unsigned long flags;						\
	int ret;							\
									\
	_atomic_spin_lock_irqsave(v, flags);				\
	ret = (v->counter c_op i);					\
	_atomic_spin_unlock_irqrestore(v, flags);			\
									\

Annotation

Implementation Notes