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 "qemu/thread.h"
  18 #include "block/aio.h"
  19 #include "sysemu/iothread.h"
  20 #include "qmp-commands.h"
  21
  22 #define IOTHREADS_PATH "/objects"
  23
  24 typedef ObjectClass IOThreadClass;
  25 struct IOThread {
  26     Object parent_obj;
  27
  28     QemuThread thread;
  29     AioContext *ctx;
  30     QemuMutex init_done_lock;
  31     QemuCond init_done_cond;    /* is thread initialization done? */
  32     bool stopping;
  33     int thread_id;
  34 };
  35
  36 #define IOTHREAD_GET_CLASS(obj) \
  37    OBJECT_GET_CLASS(IOThreadClass, obj, TYPE_IOTHREAD)
  38 #define IOTHREAD_CLASS(klass) \
  39    OBJECT_CLASS_CHECK(IOThreadClass, klass, TYPE_IOTHREAD)
  40
  41 static void *iothread_run(void *opaque)
  42 {
  43     IOThread *iothread = opaque;
  44
  45     qemu_mutex_lock(&iothread->init_done_lock);
  46     iothread->thread_id = qemu_get_thread_id();
  47     qemu_cond_signal(&iothread->init_done_cond);
  48     qemu_mutex_unlock(&iothread->init_done_lock);
  49
  50     while (!iothread->stopping) {
  51         aio_context_acquire(iothread->ctx);
  52         while (!iothread->stopping && aio_poll(iothread->ctx, true)) {
  53             /* Progress was made, keep going */
  54         }
  55         aio_context_release(iothread->ctx);
  56     }
  57     return NULL;
  58 }
  59
  60 static void iothread_instance_finalize(Object *obj)
  61 {
  62     IOThread *iothread = IOTHREAD(obj);
  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
  72 static void iothread_complete(UserCreatable *obj, Error **errp)
  73 {
  74     IOThread *iothread = IOTHREAD(obj);
  75
  76     iothread->stopping = false;
  77     iothread->ctx = aio_context_new();
  78     iothread->thread_id = -1;
  79
  80     qemu_mutex_init(&iothread->init_done_lock);
  81     qemu_cond_init(&iothread->init_done_cond);
  82
  83     /* This assumes we are called from a thread with useful CPU affinity for us
  84      * to inherit.
  85      */
  86     qemu_thread_create(&iothread->thread, "iothread", iothread_run,
  87                        iothread, QEMU_THREAD_JOINABLE);
  88
  89     /* Wait for initialization to complete */
  90     qemu_mutex_lock(&iothread->init_done_lock);
  91     while (iothread->thread_id == -1) {
  92         qemu_cond_wait(&iothread->init_done_cond,
  93                        &iothread->init_done_lock);
  94     }
  95     qemu_mutex_unlock(&iothread->init_done_lock);
  96 }
  97
  98 static void iothread_class_init(ObjectClass *klass, void *class_data)
  99 {
 100     UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
 101     ucc->complete = iothread_complete;
 102 }
 103
 104 static const TypeInfo iothread_info = {
 105     .name = TYPE_IOTHREAD,
 106     .parent = TYPE_OBJECT,
 107     .class_init = iothread_class_init,
 108     .instance_size = sizeof(IOThread),
 109     .instance_finalize = iothread_instance_finalize,
 110     .interfaces = (InterfaceInfo[]) {
 111         {TYPE_USER_CREATABLE},
 112         {}
 113     },
 114 };
 115
 116 static void iothread_register_types(void)
 117 {
 118     type_register_static(&iothread_info);
 119 }
 120
 121 type_init(iothread_register_types)
 122
 123 IOThread *iothread_find(const char *id)
 124 {
 125     Object *container = container_get(object_get_root(), IOTHREADS_PATH);
 126     Object *child;
 127
 128     child = object_property_get_link(container, id, NULL);
 129     if (!child) {
 130         return NULL;
 131     }
 132     return (IOThread *)object_dynamic_cast(child, TYPE_IOTHREAD);
 133 }
 134
 135 char *iothread_get_id(IOThread *iothread)
 136 {
 137     return object_get_canonical_path_component(OBJECT(iothread));
 138 }
 139
 140 AioContext *iothread_get_aio_context(IOThread *iothread)
 141 {
 142     return iothread->ctx;
 143 }
 144
 145 static int query_one_iothread(Object *object, void *opaque)
 146 {
 147     IOThreadInfoList ***prev = opaque;
 148     IOThreadInfoList *elem;
 149     IOThreadInfo *info;
 150     IOThread *iothread;
 151
 152     iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD);
 153     if (!iothread) {
 154         return 0;
 155     }
 156
 157     info = g_new0(IOThreadInfo, 1);
 158     info->id = iothread_get_id(iothread);
 159     info->thread_id = iothread->thread_id;
 160
 161     elem = g_new0(IOThreadInfoList, 1);
 162     elem->value = info;
 163     elem->next = NULL;
 164
 165     **prev = elem;
 166     *prev = &elem->next;
 167     return 0;
 168 }
 169
 170 IOThreadInfoList *qmp_query_iothreads(Error **errp)
 171 {
 172     IOThreadInfoList *head = NULL;
 173     IOThreadInfoList **prev = &head;
 174     Object *container = container_get(object_get_root(), IOTHREADS_PATH);
 175
 176     object_child_foreach(container, query_one_iothread, &prev);
 177     return head;
 178 }