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     bool blocking;
  35
  36     qemu_mutex_lock(&iothread->init_done_lock);
  37     iothread->thread_id = qemu_get_thread_id();
  38     qemu_cond_signal(&iothread->init_done_cond);
  39     qemu_mutex_unlock(&iothread->init_done_lock);
  40
  41     while (!iothread->stopping) {
  42         aio_context_acquire(iothread->ctx);
  43         blocking = true;
  44         while (!iothread->stopping && aio_poll(iothread->ctx, blocking)) {
  45             /* Progress was made, keep going */
  46             blocking = false;
  47         }
  48         aio_context_release(iothread->ctx);
  49     }
  50     return NULL;
  51 }
  52
  53 static void iothread_instance_finalize(Object *obj)
  54 {
  55     IOThread *iothread = IOTHREAD(obj);
  56
  57     if (!iothread->ctx) {
  58         return;
  59     }
  60     iothread->stopping = true;
  61     aio_notify(iothread->ctx);
  62     qemu_thread_join(&iothread->thread);
  63     qemu_cond_destroy(&iothread->init_done_cond);
  64     qemu_mutex_destroy(&iothread->init_done_lock);
  65     aio_context_unref(iothread->ctx);
  66 }
  67
  68 static void iothread_complete(UserCreatable *obj, Error **errp)
  69 {
  70     Error *local_error = NULL;
  71     IOThread *iothread = IOTHREAD(obj);
  72
  73     iothread->stopping = false;
  74     iothread->thread_id = -1;
  75     iothread->ctx = aio_context_new(&local_error);
  76     if (!iothread->ctx) {
  77         error_propagate(errp, local_error);
  78         return;
  79     }
  80
  81     qemu_mutex_init(&iothread->init_done_lock);
  82     qemu_cond_init(&iothread->init_done_cond);
  83
  84     /* This assumes we are called from a thread with useful CPU affinity for us
  85      * to inherit.
  86      */
  87     qemu_thread_create(&iothread->thread, "iothread", iothread_run,
  88                        iothread, QEMU_THREAD_JOINABLE);
  89
  90     /* Wait for initialization to complete */
  91     qemu_mutex_lock(&iothread->init_done_lock);
  92     while (iothread->thread_id == -1) {
  93         qemu_cond_wait(&iothread->init_done_cond,
  94                        &iothread->init_done_lock);
  95     }
  96     qemu_mutex_unlock(&iothread->init_done_lock);
  97 }
  98
  99 static void iothread_class_init(ObjectClass *klass, void *class_data)
 100 {
 101     UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
 102     ucc->complete = iothread_complete;
 103 }
 104
 105 static const TypeInfo iothread_info = {
 106     .name = TYPE_IOTHREAD,
 107     .parent = TYPE_OBJECT,
 108     .class_init = iothread_class_init,
 109     .instance_size = sizeof(IOThread),
 110     .instance_finalize = iothread_instance_finalize,
 111     .interfaces = (InterfaceInfo[]) {
 112         {TYPE_USER_CREATABLE},
 113         {}
 114     },
 115 };
 116
 117 static void iothread_register_types(void)
 118 {
 119     type_register_static(&iothread_info);
 120 }
 121
 122 type_init(iothread_register_types)
 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 }