benchmarks/cdschecker/linuxrwlock/linuxrwlocks.c.in

   1 #include <stdio.h>
   2 #include <threads.h>
   3 #include <stdatomic.h>
   4
   5 #include "librace.h"
   6
   7 #define RW_LOCK_BIAS            0x00100000
   8 #define WRITE_LOCK_CMP          RW_LOCK_BIAS
   9
  10 /** Example implementation of linux rw lock along with 2 thread test
  11  *  driver... */
  12
  13 typedef union {
  14         atomic_int lock;
  15 } rwlock_t;
  16
  17 static inline int write_trylock(rwlock_t *rw)
  18 {
  19         int priorvalue = atomic_fetch_sub_explicit(&rw->lock, RW_LOCK_BIAS, memory_order_seq_cst);
  20         if (priorvalue == RW_LOCK_BIAS)
  21                 return 1;
  22
  23         atomic_fetch_add_explicit(&rw->lock, RW_LOCK_BIAS, memory_order_seq_cst);
  24         return 0;
  25 }
  26
  27 static inline void write_unlock(rwlock_t *rw)
  28 {
  29         atomic_fetch_add_explicit(&rw->lock, RW_LOCK_BIAS, memory_order_seq_cst);
  30 }
  31
  32 rwlock_t mylock;
  33 int shareddata;
  34
  35 static void a(void *obj) {
  36         int i;
  37         for(i = 0; i < PROBLEMSIZE; i++) {
  38                 if (write_trylock(&mylock)) {
  39                         write_unlock(&mylock);
  40                 }
  41         }
  42 }
  43
  44 int user_main(int argc, char **argv)
  45 {
  46         thrd_t t1, t2;
  47         atomic_init(&mylock.lock, RW_LOCK_BIAS);
  48
  49         thrd_create(&t1, (thrd_start_t)&a, NULL);
  50         thrd_create(&t2, (thrd_start_t)&a, NULL);
  51
  52         thrd_join(t1);
  53         thrd_join(t2);
  54
  55         return 0;
  56 }