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 "block/block.h" 20 #include "sysemu/iothread.h" 21 #include "qmp-commands.h" 22 #include "qemu/error-report.h" 23 #include "qemu/rcu.h" 24 #include "qemu/main-loop.h" 25 26 typedef ObjectClass IOThreadClass; 27 28 #define IOTHREAD_GET_CLASS(obj) \ 29 OBJECT_GET_CLASS(IOThreadClass, obj, TYPE_IOTHREAD) 30 #define IOTHREAD_CLASS(klass) \ 31 OBJECT_CLASS_CHECK(IOThreadClass, klass, TYPE_IOTHREAD) 32 33 static __thread IOThread *my_iothread; 34 35 AioContext *qemu_get_current_aio_context(void) 36 { 37 return my_iothread ? my_iothread->ctx : qemu_get_aio_context(); 38 } 39 40 static void *iothread_run(void *opaque) 41 { 42 IOThread *iothread = opaque; 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 (!atomic_read(&iothread->stopping)) { 53 aio_poll(iothread->ctx, true); 54 } 55 56 rcu_unregister_thread(); 57 return NULL; 58 } 59 60 static int iothread_stop(Object *object, void *opaque) 61 { 62 IOThread *iothread; 63 64 iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD); 65 if (!iothread || !iothread->ctx) { 66 return 0; 67 } 68 iothread->stopping = true; 69 aio_notify(iothread->ctx); 70 qemu_thread_join(&iothread->thread); 71 return 0; 72 } 73 74 static void iothread_instance_finalize(Object *obj) 75 { 76 IOThread *iothread = IOTHREAD(obj); 77 78 iothread_stop(obj, NULL); 79 qemu_cond_destroy(&iothread->init_done_cond); 80 qemu_mutex_destroy(&iothread->init_done_lock); 81 if (!iothread->ctx) { 82 return; 83 } 84 aio_context_unref(iothread->ctx); 85 } 86 87 static void iothread_complete(UserCreatable *obj, Error **errp) 88 { 89 Error *local_error = NULL; 90 IOThread *iothread = IOTHREAD(obj); 91 char *name, *thread_name; 92 93 iothread->stopping = false; 94 iothread->thread_id = -1; 95 iothread->ctx = aio_context_new(&local_error); 96 if (!iothread->ctx) { 97 error_propagate(errp, local_error); 98 return; 99 } 100 101 aio_context_set_poll_params(iothread->ctx, 102 iothread->poll_max_ns, 103 iothread->poll_grow, 104 iothread->poll_shrink, 105 &local_error); 106 if (local_error) { 107 error_propagate(errp, local_error); 108 aio_context_unref(iothread->ctx); 109 iothread->ctx = NULL; 110 return; 111 } 112 113 qemu_mutex_init(&iothread->init_done_lock); 114 qemu_cond_init(&iothread->init_done_cond); 115 116 /* This assumes we are called from a thread with useful CPU affinity for us 117 * to inherit. 118 */ 119 name = object_get_canonical_path_component(OBJECT(obj)); 120 thread_name = g_strdup_printf("IO %s", name); 121 qemu_thread_create(&iothread->thread, thread_name, iothread_run, 122 iothread, QEMU_THREAD_JOINABLE); 123 g_free(thread_name); 124 g_free(name); 125 126 /* Wait for initialization to complete */ 127 qemu_mutex_lock(&iothread->init_done_lock); 128 while (iothread->thread_id == -1) { 129 qemu_cond_wait(&iothread->init_done_cond, 130 &iothread->init_done_lock); 131 } 132 qemu_mutex_unlock(&iothread->init_done_lock); 133 } 134 135 typedef struct { 136 const char *name; 137 ptrdiff_t offset; /* field's byte offset in IOThread struct */ 138 } PollParamInfo; 139 140 static PollParamInfo poll_max_ns_info = { 141 "poll-max-ns", offsetof(IOThread, poll_max_ns), 142 }; 143 static PollParamInfo poll_grow_info = { 144 "poll-grow", offsetof(IOThread, poll_grow), 145 }; 146 static PollParamInfo poll_shrink_info = { 147 "poll-shrink", offsetof(IOThread, poll_shrink), 148 }; 149 150 static void iothread_get_poll_param(Object *obj, Visitor *v, 151 const char *name, void *opaque, Error **errp) 152 { 153 IOThread *iothread = IOTHREAD(obj); 154 PollParamInfo *info = opaque; 155 int64_t *field = (void *)iothread + info->offset; 156 157 visit_type_int64(v, name, field, errp); 158 } 159 160 static void iothread_set_poll_param(Object *obj, Visitor *v, 161 const char *name, void *opaque, Error **errp) 162 { 163 IOThread *iothread = IOTHREAD(obj); 164 PollParamInfo *info = opaque; 165 int64_t *field = (void *)iothread + info->offset; 166 Error *local_err = NULL; 167 int64_t value; 168 169 visit_type_int64(v, name, &value, &local_err); 170 if (local_err) { 171 goto out; 172 } 173 174 if (value < 0) { 175 error_setg(&local_err, "%s value must be in range [0, %"PRId64"]", 176 info->name, INT64_MAX); 177 goto out; 178 } 179 180 *field = value; 181 182 if (iothread->ctx) { 183 aio_context_set_poll_params(iothread->ctx, 184 iothread->poll_max_ns, 185 iothread->poll_grow, 186 iothread->poll_shrink, 187 &local_err); 188 } 189 190 out: 191 error_propagate(errp, local_err); 192 } 193 194 static void iothread_class_init(ObjectClass *klass, void *class_data) 195 { 196 UserCreatableClass *ucc = USER_CREATABLE_CLASS(klass); 197 ucc->complete = iothread_complete; 198 199 object_class_property_add(klass, "poll-max-ns", "int", 200 iothread_get_poll_param, 201 iothread_set_poll_param, 202 NULL, &poll_max_ns_info, &error_abort); 203 object_class_property_add(klass, "poll-grow", "int", 204 iothread_get_poll_param, 205 iothread_set_poll_param, 206 NULL, &poll_grow_info, &error_abort); 207 object_class_property_add(klass, "poll-shrink", "int", 208 iothread_get_poll_param, 209 iothread_set_poll_param, 210 NULL, &poll_shrink_info, &error_abort); 211 } 212 213 static const TypeInfo iothread_info = { 214 .name = TYPE_IOTHREAD, 215 .parent = TYPE_OBJECT, 216 .class_init = iothread_class_init, 217 .instance_size = sizeof(IOThread), 218 .instance_finalize = iothread_instance_finalize, 219 .interfaces = (InterfaceInfo[]) { 220 {TYPE_USER_CREATABLE}, 221 {} 222 }, 223 }; 224 225 static void iothread_register_types(void) 226 { 227 type_register_static(&iothread_info); 228 } 229 230 type_init(iothread_register_types) 231 232 char *iothread_get_id(IOThread *iothread) 233 { 234 return object_get_canonical_path_component(OBJECT(iothread)); 235 } 236 237 AioContext *iothread_get_aio_context(IOThread *iothread) 238 { 239 return iothread->ctx; 240 } 241 242 static int query_one_iothread(Object *object, void *opaque) 243 { 244 IOThreadInfoList ***prev = opaque; 245 IOThreadInfoList *elem; 246 IOThreadInfo *info; 247 IOThread *iothread; 248 249 iothread = (IOThread *)object_dynamic_cast(object, TYPE_IOTHREAD); 250 if (!iothread) { 251 return 0; 252 } 253 254 info = g_new0(IOThreadInfo, 1); 255 info->id = iothread_get_id(iothread); 256 info->thread_id = iothread->thread_id; 257 258 elem = g_new0(IOThreadInfoList, 1); 259 elem->value = info; 260 elem->next = NULL; 261 262 **prev = elem; 263 *prev = &elem->next; 264 return 0; 265 } 266 267 IOThreadInfoList *qmp_query_iothreads(Error **errp) 268 { 269 IOThreadInfoList *head = NULL; 270 IOThreadInfoList **prev = &head; 271 Object *container = object_get_objects_root(); 272 273 object_child_foreach(container, query_one_iothread, &prev); 274 return head; 275 } 276 277 void iothread_stop_all(void) 278 { 279 Object *container = object_get_objects_root(); 280 BlockDriverState *bs; 281 BdrvNextIterator it; 282 283 for (bs = bdrv_first(&it); bs; bs = bdrv_next(&it)) { 284 AioContext *ctx = bdrv_get_aio_context(bs); 285 if (ctx == qemu_get_aio_context()) { 286 continue; 287 } 288 aio_context_acquire(ctx); 289 bdrv_set_aio_context(bs, qemu_get_aio_context()); 290 aio_context_release(ctx); 291 } 292 293 object_child_foreach(container, iothread_stop, NULL); 294 } 295