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 "qemu/osdep.h"
  15 #include "qom/object.h"
  16 #include "qom/object_interfaces.h"
  17 #include "qemu/module.h"
  18 #include "block/aio.h"
  19 #include "sysemu/iothread.h"
  20 #include "qmp-commands.h"
  21 #include "qemu/error-report.h"
  22 #include "qemu/rcu.h"
  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     rcu_register_thread();
  37
  38     qemu_mutex_lock(&iothread->init_done_lock);
  39     iothread->thread_id = qemu_get_thread_id();
  40     qemu_cond_signal(&iothread->init_done_cond);
  41     qemu_mutex_unlock(&iothread->init_done_lock);
  42
  43     while (!iothread->stopping) {
  44         aio_context_acquire(iothread->ctx);
  45         blocking = true;
  46         while (!iothread->stopping && aio_poll(iothread->ctx, blocking)) {
  47             /* Progress was made, keep going */
  48             blocking = false;
  49         }
  50         aio_context_release(iothread->ctx);
  51     }
  52
  53     rcu_unregister_thread();
  54     return NULL;
  55 }
  56
  57 static int iothread_stop(Object *object, void *opaque)
  58 {
  59     IOThread *iothread;
  60
  61     iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD);
  62     if (!iothread || !iothread->ctx) {
  63         return 0;
  64     }
  65     iothread->stopping = true;
  66     aio_notify(iothread->ctx);
  67     qemu_thread_join(&iothread->thread);
  68     return 0;
  69 }
  70
  71 static void iothread_instance_finalize(Object *obj)
  72 {
  73     IOThread *iothread = IOTHREAD(obj);
  74
  75     iothread_stop(obj, NULL);
  76     qemu_cond_destroy(&iothread->init_done_cond);
  77     qemu_mutex_destroy(&iothread->init_done_lock);
  78     aio_context_unref(iothread->ctx);
  79 }
  80
  81 static void iothread_complete(UserCreatable *obj, Error **errp)
  82 {
  83     Error *local_error = NULL;
  84     IOThread *iothread = IOTHREAD(obj);
  85     char *name, *thread_name;
  86
  87     iothread->stopping = false;
  88     iothread->thread_id = -1;
  89     iothread->ctx = aio_context_new(&local_error);
  90     if (!iothread->ctx) {
  91         error_propagate(errp, local_error);
  92         return;
  93     }
  94
  95     qemu_mutex_init(&iothread->init_done_lock);
  96     qemu_cond_init(&iothread->init_done_cond);
  97
  98     /* This assumes we are called from a thread with useful CPU affinity for us
  99      * to inherit.
 100      */
 101     name = object_get_canonical_path_component(OBJECT(obj));
 102     thread_name = g_strdup_printf("IO %s", name);
 103     qemu_thread_create(&iothread->thread, thread_name, iothread_run,
 104                        iothread, QEMU_THREAD_JOINABLE);
 105     g_free(thread_name);
 106     g_free(name);
 107
 108     /* Wait for initialization to complete */
 109     qemu_mutex_lock(&iothread->init_done_lock);
 110     while (iothread->thread_id == -1) {
 111         qemu_cond_wait(&iothread->init_done_cond,
 112                        &iothread->init_done_lock);
 113     }
 114     qemu_mutex_unlock(&iothread->init_done_lock);
 115 }
 116
 117 static void iothread_class_init(ObjectClass *klass, void *class_data)
 118 {
 119     UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
 120     ucc->complete = iothread_complete;
 121 }
 122
 123 static const TypeInfo iothread_info = {
 124     .name = TYPE_IOTHREAD,
 125     .parent = TYPE_OBJECT,
 126     .class_init = iothread_class_init,
 127     .instance_size = sizeof(IOThread),
 128     .instance_finalize = iothread_instance_finalize,
 129     .interfaces = (InterfaceInfo[]) {
 130         {TYPE_USER_CREATABLE},
 131         {}
 132     },
 133 };
 134
 135 static void iothread_register_types(void)
 136 {
 137     type_register_static(&iothread_info);
 138 }
 139
 140 type_init(iothread_register_types)
 141
 142 char *iothread_get_id(IOThread *iothread)
 143 {
 144     return object_get_canonical_path_component(OBJECT(iothread));
 145 }
 146
 147 AioContext *iothread_get_aio_context(IOThread *iothread)
 148 {
 149     return iothread->ctx;
 150 }
 151
 152 static int query_one_iothread(Object *object, void *opaque)
 153 {
 154     IOThreadInfoList ***prev = opaque;
 155     IOThreadInfoList *elem;
 156     IOThreadInfo *info;
 157     IOThread *iothread;
 158
 159     iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD);
 160     if (!iothread) {
 161         return 0;
 162     }
 163
 164     info = g_new0(IOThreadInfo, 1);
 165     info->id = iothread_get_id(iothread);
 166     info->thread_id = iothread->thread_id;
 167
 168     elem = g_new0(IOThreadInfoList, 1);
 169     elem->value = info;
 170     elem->next = NULL;
 171
 172     **prev = elem;
 173     *prev = &elem->next;
 174     return 0;
 175 }
 176
 177 IOThreadInfoList *qmp_query_iothreads(Error **errp)
 178 {
 179     IOThreadInfoList *head = NULL;
 180     IOThreadInfoList **prev = &head;
 181     Object *container = object_get_objects_root();
 182
 183     object_child_foreach(container, query_one_iothread, &prev);
 184     return head;
 185 }
 186
 187 void iothread_stop_all(void)
 188 {
 189     Object *container = object_get_objects_root();
 190
 191     object_child_foreach(container, iothread_stop, NULL);
 192 }