LXR linux/include/asm-generic/local.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _ASM_GENERIC_LOCAL_H
   3#define _ASM_GENERIC_LOCAL_H
   4
   5#include <linux/percpu.h>
   6#include <linux/atomic.h>
   7#include <asm/types.h>
   8
   9/*
  10 * A signed long type for operations which are atomic for a single CPU.
  11 * Usually used in combination with per-cpu variables.
  12 *
  13 * This is the default implementation, which uses atomic_long_t.  Which is
  14 * rather pointless.  The whole point behind local_t is that some processors
  15 * can perform atomic adds and subtracts in a manner which is atomic wrt IRQs
  16 * running on this CPU.  local_t allows exploitation of such capabilities.
  17 */
  18
  19/* Implement in terms of atomics. */
  20
  21/* Don't use typedef: don't want them to be mixed with atomic_t's. */
  22typedef struct
  23{
  24        atomic_long_t a;
  25} local_t;
  26
  27#define LOCAL_INIT(i)   { ATOMIC_LONG_INIT(i) }
  28
  29#define local_read(l)   atomic_long_read(&(l)->a)
  30#define local_set(l,i)  atomic_long_set((&(l)->a),(i))
  31#define local_inc(l)    atomic_long_inc(&(l)->a)
  32#define local_dec(l)    atomic_long_dec(&(l)->a)
  33#define local_add(i,l)  atomic_long_add((i),(&(l)->a))
  34#define local_sub(i,l)  atomic_long_sub((i),(&(l)->a))
  35
  36#define local_sub_and_test(i, l) atomic_long_sub_and_test((i), (&(l)->a))
  37#define local_dec_and_test(l) atomic_long_dec_and_test(&(l)->a)
  38#define local_inc_and_test(l) atomic_long_inc_and_test(&(l)->a)
  39#define local_add_negative(i, l) atomic_long_add_negative((i), (&(l)->a))
  40#define local_add_return(i, l) atomic_long_add_return((i), (&(l)->a))
  41#define local_sub_return(i, l) atomic_long_sub_return((i), (&(l)->a))
  42#define local_inc_return(l) atomic_long_inc_return(&(l)->a)
  43
  44#define local_cmpxchg(l, o, n) atomic_long_cmpxchg((&(l)->a), (o), (n))
  45#define local_xchg(l, n) atomic_long_xchg((&(l)->a), (n))
  46#define local_add_unless(l, _a, u) atomic_long_add_unless((&(l)->a), (_a), (u))
  47#define local_inc_not_zero(l) atomic_long_inc_not_zero(&(l)->a)
  48
  49/* Non-atomic variants, ie. preemption disabled and won't be touched
  50 * in interrupt, etc.  Some archs can optimize this case well. */
  51#define __local_inc(l)          local_set((l), local_read(l) + 1)
  52#define __local_dec(l)          local_set((l), local_read(l) - 1)
  53#define __local_add(i,l)        local_set((l), local_read(l) + (i))
  54#define __local_sub(i,l)        local_set((l), local_read(l) - (i))
  55
  56#endif /* _ASM_GENERIC_LOCAL_H */
  57