Quelle  atomic32.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0
/*
 * atomic32.c: 32-bit atomic_t implementation
 *
 * Copyright (C) 2004 Keith M Wesolowski
 * Copyright (C) 2007 Kyle McMartin
 * 
 * Based on asm-parisc/atomic.h Copyright (C) 2000 Philipp Rumpf
 */

#include <linux/atomic.h>
#include <linux/spinlock.h>
#include <linux/module.h>

#ifdef CONFIG_SMP
#define ATOMIC_HASH_SIZE 4
#define ATOMIC_HASH(a) (&__atomic_hash[(((unsigned long)a)>>8) & (ATOMIC_HASH_SIZE-1)])

spinlock_t __atomic_hash[ATOMIC_HASH_SIZE] = {
 [0 ... (ATOMIC_HASH_SIZE-1)] = __SPIN_LOCK_UNLOCKED(__atomic_hash)
};

#else /* SMP */

static DEFINE_SPINLOCK(dummy);
#define ATOMIC_HASH_SIZE 1
#define ATOMIC_HASH(a)  (&dummy)

#endif /* SMP */

#define ATOMIC_FETCH_OP(op, c_op)     \
int arch_atomic_fetch_##op(int i, atomic_t *v)    \
{         \
 int ret;       \
 unsigned long flags;      \
 spin_lock_irqsave(ATOMIC_HASH(v), flags);   \
         \
 ret = v->counter;      \
 v->counter c_op i;      \
         \
 spin_unlock_irqrestore(ATOMIC_HASH(v), flags);   \
 return ret;       \
}         \
EXPORT_SYMBOL(arch_atomic_fetch_##op);

#define ATOMIC_OP_RETURN(op, c_op)     \
int arch_atomic_##op##_return(int i, atomic_t *v)   \
{         \
 int ret;       \
 unsigned long flags;      \
 spin_lock_irqsave(ATOMIC_HASH(v), flags);   \
         \
 ret = (v->counter c_op i);     \
         \
 spin_unlock_irqrestore(ATOMIC_HASH(v), flags);   \
 return ret;       \
}         \
EXPORT_SYMBOL(arch_atomic_##op##_return);

ATOMIC_OP_RETURN(add, +=)

ATOMIC_FETCH_OP(add, +=)
ATOMIC_FETCH_OP(and, &=)
ATOMIC_FETCH_OP(or, |=)
ATOMIC_FETCH_OP(xor, ^=)

#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN

int arch_atomic_xchg(atomic_t *v, int new)
{
 int ret;
 unsigned long flags;

 spin_lock_irqsave(ATOMIC_HASH(v), flags);
 ret = v->counter;
 v->counter = new;
 spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
 return ret;
}
EXPORT_SYMBOL(arch_atomic_xchg);

int arch_atomic_cmpxchg(atomic_t *v, int old, int new)
{
 int ret;
 unsigned long flags;

 spin_lock_irqsave(ATOMIC_HASH(v), flags);
 ret = v->counter;
 if (likely(ret == old))
  v->counter = new;

 spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
 return ret;
}
EXPORT_SYMBOL(arch_atomic_cmpxchg);

int arch_atomic_fetch_add_unless(atomic_t *v, int a, int u)
{
 int ret;
 unsigned long flags;

 spin_lock_irqsave(ATOMIC_HASH(v), flags);
 ret = v->counter;
 if (ret != u)
  v->counter += a;
 spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
 return ret;
}
EXPORT_SYMBOL(arch_atomic_fetch_add_unless);

/* Atomic operations are already serializing */
void arch_atomic_set(atomic_t *v, int i)
{
 unsigned long flags;

 spin_lock_irqsave(ATOMIC_HASH(v), flags);
 v->counter = i;
 spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
}
EXPORT_SYMBOL(arch_atomic_set);

unsigned long sp32___set_bit(unsigned long *addr, unsigned long mask)
{
 unsigned long old, flags;

 spin_lock_irqsave(ATOMIC_HASH(addr), flags);
 old = *addr;
 *addr = old | mask;
 spin_unlock_irqrestore(ATOMIC_HASH(addr), flags);

 return old & mask;
}
EXPORT_SYMBOL(sp32___set_bit);

unsigned long sp32___clear_bit(unsigned long *addr, unsigned long mask)
{
 unsigned long old, flags;

 spin_lock_irqsave(ATOMIC_HASH(addr), flags);
 old = *addr;
 *addr = old & ~mask;
 spin_unlock_irqrestore(ATOMIC_HASH(addr), flags);

 return old & mask;
}
EXPORT_SYMBOL(sp32___clear_bit);

unsigned long sp32___change_bit(unsigned long *addr, unsigned long mask)
{
 unsigned long old, flags;

 spin_lock_irqsave(ATOMIC_HASH(addr), flags);
 old = *addr;
 *addr = old ^ mask;
 spin_unlock_irqrestore(ATOMIC_HASH(addr), flags);

 return old & mask;
}
EXPORT_SYMBOL(sp32___change_bit);

#define CMPXCHG(T)      \
 T __cmpxchg_##T(volatile T *ptr, T old, T new)  \
 {       \
  unsigned long flags;    \
  T prev;      \
        \
  spin_lock_irqsave(ATOMIC_HASH(ptr), flags); \
  if ((prev = *ptr) == old)   \
   *ptr = new;    \
  spin_unlock_irqrestore(ATOMIC_HASH(ptr), flags);\
        \
  return prev;     \
 }

CMPXCHG(u8)
CMPXCHG(u16)
CMPXCHG(u32)
CMPXCHG(u64)
EXPORT_SYMBOL(__cmpxchg_u8);
EXPORT_SYMBOL(__cmpxchg_u16);
EXPORT_SYMBOL(__cmpxchg_u32);
EXPORT_SYMBOL(__cmpxchg_u64);

unsigned long __xchg_u32(volatile u32 *ptr, u32 new)
{
 unsigned long flags;
 u32 prev;

 spin_lock_irqsave(ATOMIC_HASH(ptr), flags);
 prev = *ptr;
 *ptr = new;
 spin_unlock_irqrestore(ATOMIC_HASH(ptr), flags);

 return (unsigned long)prev;
}
EXPORT_SYMBOL(__xchg_u32);