include/asm-i386/local.h

   1 #ifndef _ARCH_I386_LOCAL_H
   2 #define _ARCH_I386_LOCAL_H
   3
   4 #include <linux/percpu.h>
   5
   6 typedef struct
   7 {
   8         volatile long counter;
   9 } local_t;
  10
  11 #define LOCAL_INIT(i)   { (i) }
  12
  13 #define local_read(v)   ((v)->counter)
  14 #define local_set(v,i)  (((v)->counter) = (i))
  15
  16 static __inline__ void local_inc(local_t *v)
  17 {
  18         __asm__ __volatile__(
  19                 "incl %0"
  20                 :"+m" (v->counter));
  21 }
  22
  23 static __inline__ void local_dec(local_t *v)
  24 {
  25         __asm__ __volatile__(
  26                 "decl %0"
  27                 :"+m" (v->counter));
  28 }
  29
  30 static __inline__ void local_add(long i, local_t *v)
  31 {
  32         __asm__ __volatile__(
  33                 "addl %1,%0"
  34                 :"+m" (v->counter)
  35                 :"ir" (i));
  36 }
  37
  38 static __inline__ void local_sub(long i, local_t *v)
  39 {
  40         __asm__ __volatile__(
  41                 "subl %1,%0"
  42                 :"+m" (v->counter)
  43                 :"ir" (i));
  44 }
  45
  46 /* On x86, these are no better than the atomic variants. */
  47 #define __local_inc(l)          local_inc(l)
  48 #define __local_dec(l)          local_dec(l)
  49 #define __local_add(i,l)        local_add((i),(l))
  50 #define __local_sub(i,l)        local_sub((i),(l))
  51
  52 /* Use these for per-cpu local_t variables: on some archs they are
  53  * much more efficient than these naive implementations.  Note they take
  54  * a variable, not an address.
  55  */
  56
  57 /* Need to disable preemption for the cpu local counters otherwise we could
  58    still access a variable of a previous CPU in a non atomic way. */
  59 #define cpu_local_wrap_v(v)             \
  60         ({ local_t res__;               \
  61            preempt_disable();           \
  62            res__ = (v);                 \
  63            preempt_enable();            \
  64            res__; })
  65 #define cpu_local_wrap(v)               \
  66         ({ preempt_disable();           \
  67            v;                           \
  68            preempt_enable(); })         \
  69
  70 #define cpu_local_read(v)    cpu_local_wrap_v(local_read(&__get_cpu_var(v)))
  71 #define cpu_local_set(v, i)  cpu_local_wrap(local_set(&__get_cpu_var(v), (i)))
  72 #define cpu_local_inc(v)     cpu_local_wrap(local_inc(&__get_cpu_var(v)))
  73 #define cpu_local_dec(v)     cpu_local_wrap(local_dec(&__get_cpu_var(v)))
  74 #define cpu_local_add(i, v)  cpu_local_wrap(local_add((i), &__get_cpu_var(v)))
  75 #define cpu_local_sub(i, v)  cpu_local_wrap(local_sub((i), &__get_cpu_var(v)))
  76
  77 #define __cpu_local_inc(v)      cpu_local_inc(v)
  78 #define __cpu_local_dec(v)      cpu_local_dec(v)
  79 #define __cpu_local_add(i, v)   cpu_local_add((i), (v))
  80 #define __cpu_local_sub(i, v)   cpu_local_sub((i), (v))
  81
  82 #endif /* _ARCH_I386_LOCAL_H */