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                 :"m" (v->counter));
  22 }
  23
  24 static __inline__ void local_dec(local_t *v)
  25 {
  26         __asm__ __volatile__(
  27                 "decl %0"
  28                 :"=m" (v->counter)
  29                 :"m" (v->counter));
  30 }
  31
  32 static __inline__ void local_add(long i, local_t *v)
  33 {
  34         __asm__ __volatile__(
  35                 "addl %1,%0"
  36                 :"=m" (v->counter)
  37                 :"ir" (i), "m" (v->counter));
  38 }
  39
  40 static __inline__ void local_sub(long i, local_t *v)
  41 {
  42         __asm__ __volatile__(
  43                 "subl %1,%0"
  44                 :"=m" (v->counter)
  45                 :"ir" (i), "m" (v->counter));
  46 }
  47
  48 /* On x86, these are no better than the atomic variants. */
  49 #define __local_inc(l)          local_inc(l)
  50 #define __local_dec(l)          local_dec(l)
  51 #define __local_add(i,l)        local_add((i),(l))
  52 #define __local_sub(i,l)        local_sub((i),(l))
  53
  54 /* Use these for per-cpu local_t variables: on some archs they are
  55  * much more efficient than these naive implementations.  Note they take
  56  * a variable, not an address.
  57  */
  58
  59 /* Need to disable preemption for the cpu local counters otherwise we could
  60    still access a variable of a previous CPU in a non atomic way. */
  61 #define cpu_local_wrap_v(v)             \
  62         ({ local_t res__;               \
  63            preempt_disable();           \
  64            res__ = (v);                 \
  65            preempt_enable();            \
  66            res__; })
  67 #define cpu_local_wrap(v)               \
  68         ({ preempt_disable();           \
  69            v;                           \
  70            preempt_enable(); })         \
  71
  72 #define cpu_local_read(v)    cpu_local_wrap_v(local_read(&__get_cpu_var(v)))
  73 #define cpu_local_set(v, i)  cpu_local_wrap(local_set(&__get_cpu_var(v), (i)))
  74 #define cpu_local_inc(v)     cpu_local_wrap(local_inc(&__get_cpu_var(v)))
  75 #define cpu_local_dec(v)     cpu_local_wrap(local_dec(&__get_cpu_var(v)))
  76 #define cpu_local_add(i, v)  cpu_local_wrap(local_add((i), &__get_cpu_var(v)))
  77 #define cpu_local_sub(i, v)  cpu_local_wrap(local_sub((i), &__get_cpu_var(v)))
  78
  79 #define __cpu_local_inc(v)      cpu_local_inc(v)
  80 #define __cpu_local_dec(v)      cpu_local_dec(v)
  81 #define __cpu_local_add(i, v)   cpu_local_add((i), (v))
  82 #define __cpu_local_sub(i, v)   cpu_local_sub((i), (v))
  83
  84 #endif /* _ARCH_I386_LOCAL_H */