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