include/asm-generic/local.h

   1 #ifndef _ASM_GENERIC_LOCAL_H
   2 #define _ASM_GENERIC_LOCAL_H
   3
   4 #include <linux/percpu.h>
   5 #include <asm/atomic.h>
   6 #include <asm/types.h>
   7
   8 /*
   9  * A signed long type for operations which are atomic for a single CPU.
  10  * Usually used in combination with per-cpu variables.
  11  *
  12  * This is the default implementation, which uses atomic_long_t.  Which is
  13  * rather pointless.  The whole point behind local_t is that some processors
  14  * can perform atomic adds and subtracts in a manner which is atomic wrt IRQs
  15  * running on this CPU.  local_t allows exploitation of such capabilities.
  16  */
  17
  18 /* Implement in terms of atomics. */
  19
  20 /* Don't use typedef: don't want them to be mixed with atomic_t's. */
  21 typedef struct
  22 {
  23         atomic_long_t a;
  24 } local_t;
  25
  26 #define LOCAL_INIT(i)   { ATOMIC_LONG_INIT(i) }
  27
  28 #define local_read(l)   atomic_long_read(&(l)->a)
  29 #define local_set(l,i)  atomic_long_set((&(l)->a),(i))
  30 #define local_inc(l)    atomic_long_inc(&(l)->a)
  31 #define local_dec(l)    atomic_long_dec(&(l)->a)
  32 #define local_add(i,l)  atomic_long_add((i),(&(l)->a))
  33 #define local_sub(i,l)  atomic_long_sub((i),(&(l)->a))
  34
  35 #define local_sub_and_test(i, l) atomic_long_sub_and_test((i), (&(l)->a))
  36 #define local_dec_and_test(l) atomic_long_dec_and_test(&(l)->a)
  37 #define local_inc_and_test(l) atomic_long_inc_and_test(&(l)->a)
  38 #define local_add_negative(i, l) atomic_long_add_negative((i), (&(l)->a))
  39 #define local_add_return(i, l) atomic_long_add_return((i), (&(l)->a))
  40 #define local_sub_return(i, l) atomic_long_sub_return((i), (&(l)->a))
  41 #define local_inc_return(l) atomic_long_inc_return(&(l)->a)
  42
  43 #define local_cmpxchg(l, o, n) atomic_long_cmpxchg((&(l)->a), (o), (n))
  44 #define local_xchg(l, n) atomic_long_xchg((&(l)->a), (n))
  45 #define local_add_unless(l, _a, u) atomic_long_add_unless((&(l)->a), (_a), (u))
  46 #define local_inc_not_zero(l) atomic_long_inc_not_zero(&(l)->a)
  47
  48 /* Non-atomic variants, ie. preemption disabled and won't be touched
  49  * in interrupt, etc.  Some archs can optimize this case well. */
  50 #define __local_inc(l)          local_set((l), local_read(l) + 1)
  51 #define __local_dec(l)          local_set((l), local_read(l) - 1)
  52 #define __local_add(i,l)        local_set((l), local_read(l) + (i))
  53 #define __local_sub(i,l)        local_set((l), local_read(l) - (i))
  54
  55 /* Use these for per-cpu local_t variables: on some archs they are
  56  * much more efficient than these naive implementations.  Note they take
  57  * a variable (eg. mystruct.foo), not an address.
  58  */
  59 #define cpu_local_read(l)       local_read(&__get_cpu_var(l))
  60 #define cpu_local_set(l, i)     local_set(&__get_cpu_var(l), (i))
  61 #define cpu_local_inc(l)        local_inc(&__get_cpu_var(l))
  62 #define cpu_local_dec(l)        local_dec(&__get_cpu_var(l))
  63 #define cpu_local_add(i, l)     local_add((i), &__get_cpu_var(l))
  64 #define cpu_local_sub(i, l)     local_sub((i), &__get_cpu_var(l))
  65
  66 /* Non-atomic increments, ie. preemption disabled and won't be touched
  67  * in interrupt, etc.  Some archs can optimize this case well.
  68  */
  69 #define __cpu_local_inc(l)      __local_inc(&__get_cpu_var(l))
  70 #define __cpu_local_dec(l)      __local_dec(&__get_cpu_var(l))
  71 #define __cpu_local_add(i, l)   __local_add((i), &__get_cpu_var(l))
  72 #define __cpu_local_sub(i, l)   __local_sub((i), &__get_cpu_var(l))
  73
  74 #endif /* _ASM_GENERIC_LOCAL_H */