local.h 2.4 KB

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