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 #include "qemu/main-loop.h"
  24
  25 typedef ObjectClass IOThreadClass;
  26
  27 #define IOTHREAD_GET_CLASS(obj) \
  28    OBJECT_GET_CLASS(IOThreadClass, obj, TYPE_IOTHREAD)
  29 #define IOTHREAD_CLASS(klass) \
  30    OBJECT_CLASS_CHECK(IOThreadClass, klass, TYPE_IOTHREAD)
  31
  32 static __thread IOThread *my_iothread;
  33
  34 AioContext *qemu_get_current_aio_context(void)
  35 {
  36     return my_iothread ? my_iothread->ctx : qemu_get_aio_context();
  37 }
  38
  39 static void *iothread_run(void *opaque)
  40 {
  41     IOThread *iothread = opaque;
  42     bool blocking;
  43
  44     rcu_register_thread();
  45
  46     my_iothread = iothread;
  47     qemu_mutex_lock(&iothread->init_done_lock);
  48     iothread->thread_id = qemu_get_thread_id();
  49     qemu_cond_signal(&iothread->init_done_cond);
  50     qemu_mutex_unlock(&iothread->init_done_lock);
  51
  52     while (!iothread->stopping) {
  53         aio_context_acquire(iothread->ctx);
  54         blocking = true;
  55         while (!iothread->stopping && aio_poll(iothread->ctx, blocking)) {
  56             /* Progress was made, keep going */
  57             blocking = false;
  58         }
  59         aio_context_release(iothread->ctx);
  60     }
  61
  62     rcu_unregister_thread();
  63     return NULL;
  64 }
  65
  66 static int iothread_stop(Object *object, void *opaque)
  67 {
  68     IOThread *iothread;
  69
  70     iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD);
  71     if (!iothread || !iothread->ctx) {
  72         return 0;
  73     }
  74     iothread->stopping = true;
  75     aio_notify(iothread->ctx);
  76     qemu_thread_join(&iothread->thread);
  77     return 0;
  78 }
  79
  80 static void iothread_instance_finalize(Object *obj)
  81 {
  82     IOThread *iothread = IOTHREAD(obj);
  83
  84     iothread_stop(obj, NULL);
  85     qemu_cond_destroy(&iothread->init_done_cond);
  86     qemu_mutex_destroy(&iothread->init_done_lock);
  87     if (!iothread->ctx) {
  88         return;
  89     }
  90     aio_context_unref(iothread->ctx);
  91 }
  92
  93 static void iothread_complete(UserCreatable *obj, Error **errp)
  94 {
  95     Error *local_error = NULL;
  96     IOThread *iothread = IOTHREAD(obj);
  97     char *name, *thread_name;
  98
  99     iothread->stopping = false;
 100     iothread->thread_id = -1;
 101     iothread->ctx = aio_context_new(&local_error);
 102     if (!iothread->ctx) {
 103         error_propagate(errp, local_error);
 104         return;
 105     }
 106
 107     qemu_mutex_init(&iothread->init_done_lock);
 108     qemu_cond_init(&iothread->init_done_cond);
 109
 110     /* This assumes we are called from a thread with useful CPU affinity for us
 111      * to inherit.
 112      */
 113     name = object_get_canonical_path_component(OBJECT(obj));
 114     thread_name = g_strdup_printf("IO %s", name);
 115     qemu_thread_create(&iothread->thread, thread_name, iothread_run,
 116                        iothread, QEMU_THREAD_JOINABLE);
 117     g_free(thread_name);
 118     g_free(name);
 119
 120     /* Wait for initialization to complete */
 121     qemu_mutex_lock(&iothread->init_done_lock);
 122     while (iothread->thread_id == -1) {
 123         qemu_cond_wait(&iothread->init_done_cond,
 124                        &iothread->init_done_lock);
 125     }
 126     qemu_mutex_unlock(&iothread->init_done_lock);
 127 }
 128
 129 static void iothread_class_init(ObjectClass *klass, void *class_data)
 130 {
 131     UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass);
 132     ucc->complete = iothread_complete;
 133 }
 134
 135 static const TypeInfo iothread_info = {
 136     .name = TYPE_IOTHREAD,
 137     .parent = TYPE_OBJECT,
 138     .class_init = iothread_class_init,
 139     .instance_size = sizeof(IOThread),
 140     .instance_finalize = iothread_instance_finalize,
 141     .interfaces = (InterfaceInfo[]) {
 142         {TYPE_USER_CREATABLE},
 143         {}
 144     },
 145 };
 146
 147 static void iothread_register_types(void)
 148 {
 149     type_register_static(&iothread_info);
 150 }
 151
 152 type_init(iothread_register_types)
 153
 154 char *iothread_get_id(IOThread *iothread)
 155 {
 156     return object_get_canonical_path_component(OBJECT(iothread));
 157 }
 158
 159 AioContext *iothread_get_aio_context(IOThread *iothread)
 160 {
 161     return iothread->ctx;
 162 }
 163
 164 static int query_one_iothread(Object *object, void *opaque)
 165 {
 166     IOThreadInfoList ***prev = opaque;
 167     IOThreadInfoList *elem;
 168     IOThreadInfo *info;
 169     IOThread *iothread;
 170
 171     iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD);
 172     if (!iothread) {
 173         return 0;
 174     }
 175
 176     info = g_new0(IOThreadInfo, 1);
 177     info->id = iothread_get_id(iothread);
 178     info->thread_id = iothread->thread_id;
 179
 180     elem = g_new0(IOThreadInfoList, 1);
 181     elem->value = info;
 182     elem->next = NULL;
 183
 184     **prev = elem;
 185     *prev = &elem->next;
 186     return 0;
 187 }
 188
 189 IOThreadInfoList *qmp_query_iothreads(Error **errp)
 190 {
 191     IOThreadInfoList *head = NULL;
 192     IOThreadInfoList **prev = &head;
 193     Object *container = object_get_objects_root();
 194
 195     object_child_foreach(container, query_one_iothread, &prev);
 196     return head;
 197 }
 198
 199 void iothread_stop_all(void)
 200 {
 201     Object *container = object_get_objects_root();
 202
 203     object_child_foreach(container, iothread_stop, NULL);
 204 }