include/asm-generic/local.h

   1 #ifndef _ASM_GENERIC_LOCAL_H
   2 #define _ASM_GENERIC_LOCAL_H
   3
   4 #include <linux/config.h>
   5 #include <linux/percpu.h>
   6 #include <linux/hardirq.h>
   7 #include <asm/types.h>
   8
   9 /* An unsigned long type for operations which are atomic for a single
  10  * CPU.  Usually used in combination with per-cpu variables. */
  11
  12 #if BITS_PER_LONG == 32
  13 /* Implement in terms of atomics. */
  14
  15 /* Don't use typedef: don't want them to be mixed with atomic_t's. */
  16 typedef struct
  17 {
  18         atomic_t a;
  19 } local_t;
  20
  21 #define LOCAL_INIT(i)   { ATOMIC_INIT(i) }
  22
  23 #define local_read(l)   ((unsigned long)atomic_read(&(l)->a))
  24 #define local_set(l,i)  atomic_set((&(l)->a),(i))
  25 #define local_inc(l)    atomic_inc(&(l)->a)
  26 #define local_dec(l)    atomic_dec(&(l)->a)
  27 #define local_add(i,l)  atomic_add((i),(&(l)->a))
  28 #define local_sub(i,l)  atomic_sub((i),(&(l)->a))
  29
  30 /* Non-atomic variants, ie. preemption disabled and won't be touched
  31  * in interrupt, etc.  Some archs can optimize this case well. */
  32 #define __local_inc(l)          local_set((l), local_read(l) + 1)
  33 #define __local_dec(l)          local_set((l), local_read(l) - 1)
  34 #define __local_add(i,l)        local_set((l), local_read(l) + (i))
  35 #define __local_sub(i,l)        local_set((l), local_read(l) - (i))
  36
  37 #else /* ... can't use atomics. */
  38 /* Implement in terms of three variables.
  39    Another option would be to use local_irq_save/restore. */
  40
  41 typedef struct
  42 {
  43         /* 0 = in hardirq, 1 = in softirq, 2 = usermode. */
  44         unsigned long v[3];
  45 } local_t;
  46
  47 #define _LOCAL_VAR(l)   ((l)->v[!in_interrupt() + !in_irq()])
  48
  49 #define LOCAL_INIT(i)   { { (i), 0, 0 } }
  50
  51 static inline unsigned long local_read(local_t *l)
  52 {
  53         return l->v[0] + l->v[1] + l->v[2];
  54 }
  55
  56 static inline void local_set(local_t *l, unsigned long v)
  57 {
  58         l->v[0] = v;
  59         l->v[1] = l->v[2] = 0;
  60 }
  61
  62 static inline void local_inc(local_t *l)
  63 {
  64         preempt_disable();
  65         _LOCAL_VAR(l)++;
  66         preempt_enable();
  67 }
  68
  69 static inline void local_dec(local_t *l)
  70 {
  71         preempt_disable();
  72         _LOCAL_VAR(l)--;
  73         preempt_enable();
  74 }
  75
  76 static inline void local_add(unsigned long v, local_t *l)
  77 {
  78         preempt_disable();
  79         _LOCAL_VAR(l) += v;
  80         preempt_enable();
  81 }
  82
  83 static inline void local_sub(unsigned long v, local_t *l)
  84 {
  85         preempt_disable();
  86         _LOCAL_VAR(l) -= v;
  87         preempt_enable();
  88 }
  89
  90 /* Non-atomic variants, ie. preemption disabled and won't be touched
  91  * in interrupt, etc.  Some archs can optimize this case well. */
  92 #define __local_inc(l)          ((l)->v[0]++)
  93 #define __local_dec(l)          ((l)->v[0]--)
  94 #define __local_add(i,l)        ((l)->v[0] += (i))
  95 #define __local_sub(i,l)        ((l)->v[0] -= (i))
  96
  97 #endif /* Non-atomic implementation */
  98
  99 /* Use these for per-cpu local_t variables: on some archs they are
 100  * much more efficient than these naive implementations.  Note they take
 101  * a variable (eg. mystruct.foo), not an address.
 102  */
 103 #define cpu_local_read(v)       local_read(&__get_cpu_var(v))
 104 #define cpu_local_set(v, i)     local_set(&__get_cpu_var(v), (i))
 105 #define cpu_local_inc(v)        local_inc(&__get_cpu_var(v))
 106 #define cpu_local_dec(v)        local_dec(&__get_cpu_var(v))
 107 #define cpu_local_add(i, v)     local_add((i), &__get_cpu_var(v))
 108 #define cpu_local_sub(i, v)     local_sub((i), &__get_cpu_var(v))
 109
 110 /* Non-atomic increments, ie. preemption disabled and won't be touched
 111  * in interrupt, etc.  Some archs can optimize this case well.
 112  */
 113 #define __cpu_local_inc(v)      __local_inc(&__get_cpu_var(v))
 114 #define __cpu_local_dec(v)      __local_dec(&__get_cpu_var(v))
 115 #define __cpu_local_add(i, v)   __local_add((i), &__get_cpu_var(v))
 116 #define __cpu_local_sub(i, v)   __local_sub((i), &__get_cpu_var(v))
 117
 118 #endif /* _ASM_GENERIC_LOCAL_H */