urcu.h

   1 #ifndef _URCU_H
   2 #define _URCU_H
   3
   4 /* The "volatile" is due to gcc bugs */
   5 #define barrier() __asm__ __volatile__("": : :"memory")
   6
   7 /* x86 32/64 specific */
   8 #define mb()    asm volatile("mfence":::"memory")
   9 #define rmb()   asm volatile("lfence":::"memory")
  10 #define wmb()   asm volatile("sfence" ::: "memory")
  11
  12
  13
  14 /* x86 32 */
  15 static inline void atomic_inc(int *v)
  16 {
  17         asm volatile("lock; incl %0"
  18                      : "+m" (v->counter));
  19 }
  20
  21 /* Nop everywhere except on alpha. */
  22 #define smp_read_barrier_depends()
  23
  24 #define SIGURCU SIGUSR1
  25
  26 /* Global quiescent period parity */
  27 extern int urcu_qparity;
  28
  29 extern int __thread urcu_active_readers[2];
  30
  31 static inline int get_urcu_qparity(void)
  32 {
  33         return urcu_qparity;
  34 }
  35
  36 /*
  37  * returns urcu_parity.
  38  */
  39 static inline int rcu_read_lock(void)
  40 {
  41         int urcu_parity = get_urcu_qparity();
  42         urcu_active_readers[urcu_parity]++;
  43         /*
  44          * Increment active readers count before accessing the pointer.
  45          * See force_mb_all_threads().
  46          */
  47         barrier();
  48         return urcu_parity;
  49 }
  50
  51 static inline void rcu_read_unlock(int urcu_parity)
  52 {
  53         barrier();
  54         /*
  55          * Finish using rcu before decrementing the pointer.
  56          * See force_mb_all_threads().
  57          */
  58         urcu_active_readers[urcu_parity]--;
  59 }
  60
  61 extern void *urcu_publish_content(void **ptr, void *new);
  62
  63 /*
  64  * Reader thread registration.
  65  */
  66 extern void urcu_register_thread(void);
  67 extern void urcu_register_thread(void);
  68
  69 #endif /* _URCU_H */