posix-aio-compat.c

   1 /*
   2  * QEMU posix-aio emulation
   3  *
   4  * Copyright IBM, Corp. 2008
   5  *
   6  * Authors:
   7  *  Anthony Liguori   <aliguori@us.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU GPL, version 2.  See
  10  * the COPYING file in the top-level directory.
  11  *
  12  */
  13
  14 #include <pthread.h>
  15 #include <unistd.h>
  16 #include <errno.h>
  17 #include <time.h>
  18 #include <string.h>
  19 #include <stdlib.h>
  20 #include <stdio.h>
  21 #include "osdep.h"
  22
  23 #include "posix-aio-compat.h"
  24
  25 static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;
  26 static pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
  27 static pthread_t thread_id;
  28 static int max_threads = 64;
  29 static int cur_threads = 0;
  30 static int idle_threads = 0;
  31 static TAILQ_HEAD(, qemu_paiocb) request_list;
  32
  33 static void die2(int err, const char *what)
  34 {
  35     fprintf(stderr, "%s failed: %s\n", what, strerror(err));
  36     abort();
  37 }
  38
  39 static void die(const char *what)
  40 {
  41     die2(errno, what);
  42 }
  43
  44 static void mutex_lock(pthread_mutex_t *mutex)
  45 {
  46     int ret = pthread_mutex_lock(mutex);
  47     if (ret) die2(ret, "pthread_mutex_lock");
  48 }
  49
  50 static void mutex_unlock(pthread_mutex_t *mutex)
  51 {
  52     int ret = pthread_mutex_unlock(mutex);
  53     if (ret) die2(ret, "pthread_mutex_unlock");
  54 }
  55
  56 static int cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex,
  57                            struct timespec *ts)
  58 {
  59     int ret = pthread_cond_timedwait(cond, mutex, ts);
  60     if (ret && ret != ETIMEDOUT) die2(ret, "pthread_cond_timedwait");
  61     return ret;
  62 }
  63
  64 static void cond_signal(pthread_cond_t *cond)
  65 {
  66     int ret = pthread_cond_signal(cond);
  67     if (ret) die2(ret, "pthread_cond_signal");
  68 }
  69
  70 static void thread_create(pthread_t *thread, pthread_attr_t *attr,
  71                           void *(*start_routine)(void*), void *arg)
  72 {
  73     int ret = pthread_create(thread, attr, start_routine, arg);
  74     if (ret) die2(ret, "pthread_create");
  75 }
  76
  77 static void *aio_thread(void *unused)
  78 {
  79     sigset_t set;
  80
  81     /* block all signals */
  82     if (sigfillset(&set)) die("sigfillset");
  83     if (sigprocmask(SIG_BLOCK, &set, NULL)) die("sigprocmask");
  84
  85     while (1) {
  86         struct qemu_paiocb *aiocb;
  87         size_t offset;
  88         int ret = 0;
  89         qemu_timeval tv;
  90         struct timespec ts;
  91
  92         qemu_gettimeofday(&tv);
  93         ts.tv_sec = tv.tv_sec + 10;
  94         ts.tv_nsec = 0;
  95
  96         mutex_lock(&lock);
  97
  98         while (TAILQ_EMPTY(&request_list) &&
  99                !(ret == ETIMEDOUT)) {
 100             ret = cond_timedwait(&cond, &lock, &ts);
 101         }
 102
 103         if (ret == ETIMEDOUT)
 104             break;
 105
 106         aiocb = TAILQ_FIRST(&request_list);
 107         TAILQ_REMOVE(&request_list, aiocb, node);
 108
 109         offset = 0;
 110         aiocb->active = 1;
 111
 112         idle_threads--;
 113         mutex_unlock(&lock);
 114
 115         while (offset < aiocb->aio_nbytes) {
 116             ssize_t len;
 117
 118             if (aiocb->is_write)
 119                 len = pwrite(aiocb->aio_fildes,
 120                              (const char *)aiocb->aio_buf + offset,
 121                              aiocb->aio_nbytes - offset,
 122                              aiocb->aio_offset + offset);
 123             else
 124                 len = pread(aiocb->aio_fildes,
 125                             (char *)aiocb->aio_buf + offset,
 126                             aiocb->aio_nbytes - offset,
 127                             aiocb->aio_offset + offset);
 128
 129             if (len == -1 && errno == EINTR)
 130                 continue;
 131             else if (len == -1) {
 132                 offset = -errno;
 133                 break;
 134             } else if (len == 0)
 135                 break;
 136
 137             offset += len;
 138         }
 139
 140         mutex_lock(&lock);
 141         aiocb->ret = offset;
 142         idle_threads++;
 143         mutex_unlock(&lock);
 144
 145         if (kill(getpid(), aiocb->ev_signo)) die("kill failed");
 146     }
 147
 148     idle_threads--;
 149     cur_threads--;
 150     mutex_unlock(&lock);
 151
 152     return NULL;
 153 }
 154
 155 static void spawn_thread(void)
 156 {
 157     int ret;
 158     pthread_attr_t attr;
 159
 160     cur_threads++;
 161     idle_threads++;
 162
 163     ret = pthread_attr_init(&attr);
 164     if (ret) die2 (ret, "pthread_attr_init");
 165     ret = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
 166     if (ret) die2 (ret, "pthread_attr_setdetachstate");
 167     thread_create(&thread_id, &attr, aio_thread, NULL);
 168     ret = pthread_attr_destroy(&attr);
 169     if (ret) die2 (ret, "pthread_attr_destroy");
 170 }
 171
 172 int qemu_paio_init(struct qemu_paioinit *aioinit)
 173 {
 174     TAILQ_INIT(&request_list);
 175
 176     return 0;
 177 }
 178
 179 static int qemu_paio_submit(struct qemu_paiocb *aiocb, int is_write)
 180 {
 181     aiocb->is_write = is_write;
 182     aiocb->ret = -EINPROGRESS;
 183     aiocb->active = 0;
 184     mutex_lock(&lock);
 185     if (idle_threads == 0 && cur_threads < max_threads)
 186         spawn_thread();
 187     TAILQ_INSERT_TAIL(&request_list, aiocb, node);
 188     mutex_unlock(&lock);
 189     cond_signal(&cond);
 190
 191     return 0;
 192 }
 193
 194 int qemu_paio_read(struct qemu_paiocb *aiocb)
 195 {
 196     return qemu_paio_submit(aiocb, 0);
 197 }
 198
 199 int qemu_paio_write(struct qemu_paiocb *aiocb)
 200 {
 201     return qemu_paio_submit(aiocb, 1);
 202 }
 203
 204 ssize_t qemu_paio_return(struct qemu_paiocb *aiocb)
 205 {
 206     ssize_t ret;
 207
 208     mutex_lock(&lock);
 209     ret = aiocb->ret;
 210     mutex_unlock(&lock);
 211
 212     return ret;
 213 }
 214
 215 int qemu_paio_error(struct qemu_paiocb *aiocb)
 216 {
 217     ssize_t ret = qemu_paio_return(aiocb);
 218
 219     if (ret < 0)
 220         ret = -ret;
 221     else
 222         ret = 0;
 223
 224     return ret;
 225 }
 226
 227 int qemu_paio_cancel(int fd, struct qemu_paiocb *aiocb)
 228 {
 229     int ret;
 230
 231     mutex_lock(&lock);
 232     if (!aiocb->active) {
 233         TAILQ_REMOVE(&request_list, aiocb, node);
 234         aiocb->ret = -ECANCELED;
 235         ret = QEMU_PAIO_CANCELED;
 236     } else if (aiocb->ret == -EINPROGRESS)
 237         ret = QEMU_PAIO_NOTCANCELED;
 238     else
 239         ret = QEMU_PAIO_ALLDONE;
 240     mutex_unlock(&lock);
 241
 242     return ret;
 243 }