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 #include "qemu/error-report.h"
  21
  22 #define IOTHREADS_PATH "/objects"
  23
  24 typedef 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
  31 static void *iothread_run(void *opaque)
  32 {
  33     IOThread *iothread = opaque;
  34
  35     qemu_mutex_lock(&iothread->init_done_lock);
  36     iothread->thread_id = qemu_get_thread_id();
  37     qemu_cond_signal(&iothread->init_done_cond);
  38     qemu_mutex_unlock(&iothread->init_done_lock);
  39
  40     while (!atomic_read(&iothread->stopping)) {
  41         aio_poll(iothread->ctx, true);
  42     }
  43     return NULL;
  44 }
  45
  46 static void iothread_instance_finalize(Object *obj)
  47 {
  48     IOThread *iothread = IOTHREAD(obj);
  49
  50     if (!iothread->ctx) {
  51         return;
  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     Error *local_error = NULL;
  64     IOThread *iothread = IOTHREAD(obj);
  65
  66     iothread->stopping = false;
  67     iothread->thread_id = -1;
  68     iothread->ctx = aio_context_new(&local_error);
  69     if (!iothread->ctx) {
  70         error_propagate(errp, local_error);
  71         return;
  72     }
  73
  74     qemu_mutex_init(&iothread->init_done_lock);
  75     qemu_cond_init(&iothread->init_done_cond);
  76
  77     /* This assumes we are called from a thread with useful CPU affinity for us
  78      * to inherit.
  79      */
  80     qemu_thread_create(&iothread->thread, "iothread", iothread_run,
  81                        iothread, QEMU_THREAD_JOINABLE);
  82
  83     /* Wait for initialization to complete */
  84     qemu_mutex_lock(&iothread->init_done_lock);
  85     while (iothread->thread_id == -1) {
  86         qemu_cond_wait(&iothread->init_done_cond,
  87                        &iothread->init_done_lock);
  88     }
  89     qemu_mutex_unlock(&iothread->init_done_lock);
  90 }
  91
  92 static void iothread_class_init(ObjectClass *klass, void *class_data)
  93 {
  94     UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
  95     ucc->complete = iothread_complete;
  96 }
  97
  98 static const TypeInfo iothread_info = {
  99     .name = TYPE_IOTHREAD,
 100     .parent = TYPE_OBJECT,
 101     .class_init = iothread_class_init,
 102     .instance_size = sizeof(IOThread),
 103     .instance_finalize = iothread_instance_finalize,
 104     .interfaces = (InterfaceInfo[]) {
 105         {TYPE_USER_CREATABLE},
 106         {}
 107     },
 108 };
 109
 110 static void iothread_register_types(void)
 111 {
 112     type_register_static(&iothread_info);
 113 }
 114
 115 type_init(iothread_register_types)
 116
 117 char *iothread_get_id(IOThread *iothread)
 118 {
 119     return object_get_canonical_path_component(OBJECT(iothread));
 120 }
 121
 122 AioContext *iothread_get_aio_context(IOThread *iothread)
 123 {
 124     return iothread->ctx;
 125 }
 126
 127 static int query_one_iothread(Object *object, void *opaque)
 128 {
 129     IOThreadInfoList ***prev = opaque;
 130     IOThreadInfoList *elem;
 131     IOThreadInfo *info;
 132     IOThread *iothread;
 133
 134     iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD);
 135     if (!iothread) {
 136         return 0;
 137     }
 138
 139     info = g_new0(IOThreadInfo, 1);
 140     info->id = iothread_get_id(iothread);
 141     info->thread_id = iothread->thread_id;
 142
 143     elem = g_new0(IOThreadInfoList, 1);
 144     elem->value = info;
 145     elem->next = NULL;
 146
 147     **prev = elem;
 148     *prev = &elem->next;
 149     return 0;
 150 }
 151
 152 IOThreadInfoList *qmp_query_iothreads(Error **errp)
 153 {
 154     IOThreadInfoList *head = NULL;
 155     IOThreadInfoList **prev = &head;
 156     Object *container = container_get(object_get_root(), IOTHREADS_PATH);
 157
 158     object_child_foreach(container, query_one_iothread, &prev);
 159     return head;
 160 }