LXR qemu/iothread.c

   1/*
   2 * Event loop thread
   3 *
   4 * Copyright Red Hat Inc., 2013
   5 *
   6 * Authors:
   7 *  Stefan Hajnoczi   <stefanha@redhat.com>
   8 *
   9 * This work is licensed under the terms of the GNU GPL, version 2 or later.
  10 * See the COPYING file in the top-level directory.
  11 *
  12 */
  13
  14#include "qemu/osdep.h"
  15#include "qom/object.h"
  16#include "qom/object_interfaces.h"
  17#include "qemu/module.h"
  18#include "block/aio.h"
  19#include "sysemu/iothread.h"
  20#include "qmp-commands.h"
  21#include "qemu/error-report.h"
  22#include "qemu/rcu.h"
  23
  24typedef ObjectClass IOThreadClass;
  25
  26#define IOTHREAD_GET_CLASS(obj) \
  27   OBJECT_GET_CLASS(IOThreadClass, obj, TYPE_IOTHREAD)
  28#define IOTHREAD_CLASS(klass) \
  29   OBJECT_CLASS_CHECK(IOThreadClass, klass, TYPE_IOTHREAD)
  30
  31static void *iothread_run(void *opaque)
  32{
  33    IOThread *iothread = opaque;
  34    bool blocking;
  35
  36    rcu_register_thread();
  37
  38    qemu_mutex_lock(&iothread->init_done_lock);
  39    iothread->thread_id = qemu_get_thread_id();
  40    qemu_cond_signal(&iothread->init_done_cond);
  41    qemu_mutex_unlock(&iothread->init_done_lock);
  42
  43    while (!iothread->stopping) {
  44        aio_context_acquire(iothread->ctx);
  45        blocking = true;
  46        while (!iothread->stopping && aio_poll(iothread->ctx, blocking)) {
  47            /* Progress was made, keep going */
  48            blocking = false;
  49        }
  50        aio_context_release(iothread->ctx);
  51    }
  52
  53    rcu_unregister_thread();
  54    return NULL;
  55}
  56
  57static void iothread_instance_finalize(Object *obj)
  58{
  59    IOThread *iothread = IOTHREAD(obj);
  60
  61    if (!iothread->ctx) {
  62        return;
  63    }
  64    iothread->stopping = true;
  65    aio_notify(iothread->ctx);
  66    qemu_thread_join(&iothread->thread);
  67    qemu_cond_destroy(&iothread->init_done_cond);
  68    qemu_mutex_destroy(&iothread->init_done_lock);
  69    aio_context_unref(iothread->ctx);
  70}
  71
  72static void iothread_complete(UserCreatable *obj, Error **errp)
  73{
  74    Error *local_error = NULL;
  75    IOThread *iothread = IOTHREAD(obj);
  76    char *name, *thread_name;
  77
  78    iothread->stopping = false;
  79    iothread->thread_id = -1;
  80    iothread->ctx = aio_context_new(&local_error);
  81    if (!iothread->ctx) {
  82        error_propagate(errp, local_error);
  83        return;
  84    }
  85
  86    qemu_mutex_init(&iothread->init_done_lock);
  87    qemu_cond_init(&iothread->init_done_cond);
  88
  89    /* This assumes we are called from a thread with useful CPU affinity for us
  90     * to inherit.
  91     */
  92    name = object_get_canonical_path_component(OBJECT(obj));
  93    thread_name = g_strdup_printf("IO %s", name);
  94    qemu_thread_create(&iothread->thread, thread_name, iothread_run,
  95                       iothread, QEMU_THREAD_JOINABLE);
  96    g_free(thread_name);
  97    g_free(name);
  98
  99    /* Wait for initialization to complete */
 100    qemu_mutex_lock(&iothread->init_done_lock);
 101    while (iothread->thread_id == -1) {
 102        qemu_cond_wait(&iothread->init_done_cond,
 103                       &iothread->init_done_lock);
 104    }
 105    qemu_mutex_unlock(&iothread->init_done_lock);
 106}
 107
 108static void iothread_class_init(ObjectClass *klass, void *class_data)
 109{
 110    UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
 111    ucc->complete = iothread_complete;
 112}
 113
 114static const TypeInfo iothread_info = {
 115    .name = TYPE_IOTHREAD,
 116    .parent = TYPE_OBJECT,
 117    .class_init = iothread_class_init,
 118    .instance_size = sizeof(IOThread),
 119    .instance_finalize = iothread_instance_finalize,
 120    .interfaces = (InterfaceInfo[]) {
 121        {TYPE_USER_CREATABLE},
 122        {}
 123    },
 124};
 125
 126static void iothread_register_types(void)
 127{
 128    type_register_static(&iothread_info);
 129}
 130
 131type_init(iothread_register_types)
 132
 133char *iothread_get_id(IOThread *iothread)
 134{
 135    return object_get_canonical_path_component(OBJECT(iothread));
 136}
 137
 138AioContext *iothread_get_aio_context(IOThread *iothread)
 139{
 140    return iothread->ctx;
 141}
 142
 143static int query_one_iothread(Object *object, void *opaque)
 144{
 145    IOThreadInfoList ***prev = opaque;
 146    IOThreadInfoList *elem;
 147    IOThreadInfo *info;
 148    IOThread *iothread;
 149
 150    iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD);
 151    if (!iothread) {
 152        return 0;
 153    }
 154
 155    info = g_new0(IOThreadInfo, 1);
 156    info->id = iothread_get_id(iothread);
 157    info->thread_id = iothread->thread_id;
 158
 159    elem = g_new0(IOThreadInfoList, 1);
 160    elem->value = info;
 161    elem->next = NULL;
 162
 163    **prev = elem;
 164    *prev = &elem->next;
 165    return 0;
 166}
 167
 168IOThreadInfoList *qmp_query_iothreads(Error **errp)
 169{
 170    IOThreadInfoList *head = NULL;
 171    IOThreadInfoList **prev = &head;
 172    Object *container = object_get_objects_root();
 173
 174    object_child_foreach(container, query_one_iothread, &prev);
 175    return head;
 176}
 177