mutex.c

   1 #include <stdio.h>
   2 #include <string.h>
   3 #include <unistd.h>
   4 #include <stdlib.h>
   5 #include <fcntl.h>
   6 #include <pthread.h>
   7 #include <sys/mman.h>
   8
   9 #include "mutex.h"
  10 #include "arch/arch.h"
  11
  12 void fio_mutex_remove(struct fio_mutex *mutex)
  13 {
  14         close(mutex->mutex_fd);
  15         munmap(mutex, sizeof(*mutex));
  16 }
  17
  18 struct fio_mutex *fio_mutex_init(int value)
  19 {
  20         char mutex_name[] = "/tmp/.fio_mutex.XXXXXX";
  21         struct fio_mutex *mutex = NULL;
  22         pthread_mutexattr_t attr;
  23         pthread_condattr_t cond;
  24         int fd;
  25
  26         fd = mkstemp(mutex_name);
  27         if (fd < 0) {
  28                 perror("open mutex");
  29                 return NULL;
  30         }
  31
  32         if (ftruncate(fd, sizeof(struct fio_mutex)) < 0) {
  33                 perror("ftruncate mutex");
  34                 goto err;
  35         }
  36
  37         mutex = mmap(NULL, sizeof(struct fio_mutex), PROT_READ | PROT_WRITE,
  38                         MAP_SHARED, fd, 0);
  39         if (mutex == MAP_FAILED) {
  40                 perror("mmap mutex");
  41                 close(fd);
  42                 mutex = NULL;
  43                 goto err;
  44         }
  45
  46         unlink(mutex_name);
  47         mutex->mutex_fd = fd;
  48         mutex->value = value;
  49
  50         if (pthread_mutexattr_init(&attr)) {
  51                 perror("pthread_mutexattr_init");
  52                 goto err;
  53         }
  54         if (pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_SHARED)) {
  55                 perror("pthread_mutexattr_setpshared");
  56                 goto err;
  57         }
  58
  59         pthread_condattr_init(&cond);
  60         pthread_condattr_setpshared(&cond, PTHREAD_PROCESS_SHARED);
  61         pthread_cond_init(&mutex->cond, &cond);
  62
  63         if (pthread_mutex_init(&mutex->lock, &attr)) {
  64                 perror("pthread_mutex_init");
  65                 goto err;
  66         }
  67
  68         return mutex;
  69 err:
  70         if (mutex)
  71                 fio_mutex_remove(mutex);
  72
  73         unlink(mutex_name);
  74         return NULL;
  75 }
  76
  77 void fio_mutex_down(struct fio_mutex *mutex)
  78 {
  79         pthread_mutex_lock(&mutex->lock);
  80
  81         while (!mutex->value) {
  82                 mutex->waiters++;
  83                 pthread_cond_wait(&mutex->cond, &mutex->lock);
  84                 mutex->waiters--;
  85         }
  86
  87         mutex->value--;
  88         pthread_mutex_unlock(&mutex->lock);
  89 }
  90
  91 void fio_mutex_up(struct fio_mutex *mutex)
  92 {
  93         pthread_mutex_lock(&mutex->lock);
  94         read_barrier();
  95         if (!mutex->value && mutex->waiters)
  96                 pthread_cond_signal(&mutex->cond);
  97         mutex->value++;
  98         pthread_mutex_unlock(&mutex->lock);
  99 }
 100
 101 void fio_mutex_down_write(struct fio_mutex *mutex)
 102 {
 103         pthread_mutex_lock(&mutex->lock);
 104
 105         while (mutex->value != 0) {
 106                 mutex->waiters++;
 107                 pthread_cond_wait(&mutex->cond, &mutex->lock);
 108                 mutex->waiters--;
 109         }
 110
 111         mutex->value--;
 112         pthread_mutex_unlock(&mutex->lock);
 113 }
 114
 115 void fio_mutex_down_read(struct fio_mutex *mutex)
 116 {
 117         pthread_mutex_lock(&mutex->lock);
 118
 119         while (mutex->value < 0) {
 120                 mutex->waiters++;
 121                 pthread_cond_wait(&mutex->cond, &mutex->lock);
 122                 mutex->waiters--;
 123         }
 124
 125         mutex->value++;
 126         pthread_mutex_unlock(&mutex->lock);
 127 }
 128
 129 void fio_mutex_up_read(struct fio_mutex *mutex)
 130 {
 131         pthread_mutex_lock(&mutex->lock);
 132         mutex->value--;
 133         read_barrier();
 134         if (mutex->value >= 0 && mutex->waiters)
 135                 pthread_cond_signal(&mutex->cond);
 136         pthread_mutex_unlock(&mutex->lock);
 137 }
 138
 139 void fio_mutex_up_write(struct fio_mutex *mutex)
 140 {
 141         pthread_mutex_lock(&mutex->lock);
 142         mutex->value++;
 143         read_barrier();
 144         if (mutex->value >= 0 && mutex->waiters)
 145                 pthread_cond_signal(&mutex->cond);
 146         pthread_mutex_unlock(&mutex->lock);
 147 }