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 "qom/object.h"
  15 #include "qom/object_interfaces.h"
  16 #include "qemu/module.h"
  17 #include "block/aio.h"
  18 #include "sysemu/iothread.h"
  19 #include "qmp-commands.h"
  20
  21 #define IOTHREADS_PATH "/objects"
  22
  23 typedef ObjectClass IOThreadClass;
  24
  25 #define IOTHREAD_GET_CLASS(obj) \
  26    OBJECT_GET_CLASS(IOThreadClass, obj, TYPE_IOTHREAD)
  27 #define IOTHREAD_CLASS(klass) \
  28    OBJECT_CLASS_CHECK(IOThreadClass, klass, TYPE_IOTHREAD)
  29
  30 static void *iothread_run(void *opaque)
  31 {
  32     IOThread *iothread = opaque;
  33
  34     qemu_mutex_lock(&iothread->init_done_lock);
  35     iothread->thread_id = qemu_get_thread_id();
  36     qemu_cond_signal(&iothread->init_done_cond);
  37     qemu_mutex_unlock(&iothread->init_done_lock);
  38
  39     while (!iothread->stopping) {
  40         aio_context_acquire(iothread->ctx);
  41         while (!iothread->stopping && aio_poll(iothread->ctx, true)) {
  42             /* Progress was made, keep going */
  43         }
  44         aio_context_release(iothread->ctx);
  45     }
  46     return NULL;
  47 }
  48
  49 static void iothread_instance_finalize(Object *obj)
  50 {
  51     IOThread *iothread = IOTHREAD(obj);
  52
  53     iothread->stopping = true;
  54     aio_notify(iothread->ctx);
  55     qemu_thread_join(&iothread->thread);
  56     qemu_cond_destroy(&iothread->init_done_cond);
  57     qemu_mutex_destroy(&iothread->init_done_lock);
  58     aio_context_unref(iothread->ctx);
  59 }
  60
  61 static void iothread_complete(UserCreatable *obj, Error **errp)
  62 {
  63     IOThread *iothread = IOTHREAD(obj);
  64
  65     iothread->stopping = false;
  66     iothread->ctx = aio_context_new();
  67     iothread->thread_id = -1;
  68
  69     qemu_mutex_init(&iothread->init_done_lock);
  70     qemu_cond_init(&iothread->init_done_cond);
  71
  72     /* This assumes we are called from a thread with useful CPU affinity for us
  73      * to inherit.
  74      */
  75     qemu_thread_create(&iothread->thread, "iothread", iothread_run,
  76                        iothread, QEMU_THREAD_JOINABLE);
  77
  78     /* Wait for initialization to complete */
  79     qemu_mutex_lock(&iothread->init_done_lock);
  80     while (iothread->thread_id == -1) {
  81         qemu_cond_wait(&iothread->init_done_cond,
  82                        &iothread->init_done_lock);
  83     }
  84     qemu_mutex_unlock(&iothread->init_done_lock);
  85 }
  86
  87 static void iothread_class_init(ObjectClass *klass, void *class_data)
  88 {
  89     UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
  90     ucc->complete = iothread_complete;
  91 }
  92
  93 static const TypeInfo iothread_info = {
  94     .name = TYPE_IOTHREAD,
  95     .parent = TYPE_OBJECT,
  96     .class_init = iothread_class_init,
  97     .instance_size = sizeof(IOThread),
  98     .instance_finalize = iothread_instance_finalize,
  99     .interfaces = (InterfaceInfo[]) {
 100         {TYPE_USER_CREATABLE},
 101         {}
 102     },
 103 };
 104
 105 static void iothread_register_types(void)
 106 {
 107     type_register_static(&iothread_info);
 108 }
 109
 110 type_init(iothread_register_types)
 111
 112 IOThread *iothread_find(const char *id)
 113 {
 114     Object *container = container_get(object_get_root(), IOTHREADS_PATH);
 115     Object *child;
 116
 117     child = object_property_get_link(container, id, NULL);
 118     if (!child) {
 119         return NULL;
 120     }
 121     return (IOThread *)object_dynamic_cast(child, TYPE_IOTHREAD);
 122 }
 123
 124 char *iothread_get_id(IOThread *iothread)
 125 {
 126     return object_get_canonical_path_component(OBJECT(iothread));
 127 }
 128
 129 AioContext *iothread_get_aio_context(IOThread *iothread)
 130 {
 131     return iothread->ctx;
 132 }
 133
 134 static int query_one_iothread(Object *object, void *opaque)
 135 {
 136     IOThreadInfoList ***prev = opaque;
 137     IOThreadInfoList *elem;
 138     IOThreadInfo *info;
 139     IOThread *iothread;
 140
 141     iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD);
 142     if (!iothread) {
 143         return 0;
 144     }
 145
 146     info = g_new0(IOThreadInfo, 1);
 147     info->id = iothread_get_id(iothread);
 148     info->thread_id = iothread->thread_id;
 149
 150     elem = g_new0(IOThreadInfoList, 1);
 151     elem->value = info;
 152     elem->next = NULL;
 153
 154     **prev = elem;
 155     *prev = &elem->next;
 156     return 0;
 157 }
 158
 159 IOThreadInfoList *qmp_query_iothreads(Error **errp)
 160 {
 161     IOThreadInfoList *head = NULL;
 162     IOThreadInfoList **prev = &head;
 163     Object *container = container_get(object_get_root(), IOTHREADS_PATH);
 164
 165     object_child_foreach(container, query_one_iothread, &prev);
 166     return head;
 167 }