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1 | /* | |
2 | * QEMU aio implementation | |
3 | * | |
4 | * Copyright IBM Corp., 2008 | |
5 | * Copyright Red Hat Inc., 2012 | |
6 | * | |
7 | * Authors: | |
8 | * Anthony Liguori <aliguori@us.ibm.com> | |
9 | * Paolo Bonzini <pbonzini@redhat.com> | |
10 | * | |
11 | * This work is licensed under the terms of the GNU GPL, version 2. See | |
12 | * the COPYING file in the top-level directory. | |
13 | * | |
14 | * Contributions after 2012-01-13 are licensed under the terms of the | |
15 | * GNU GPL, version 2 or (at your option) any later version. | |
16 | */ | |
17 | ||
18 | #include "qemu/osdep.h" | |
19 | #include "block/block.h" | |
20 | #include "qemu/main-loop.h" | |
21 | #include "qemu/queue.h" | |
22 | #include "qemu/sockets.h" | |
23 | #include "qapi/error.h" | |
24 | #include "qemu/rcu_queue.h" | |
25 | #include "qemu/error-report.h" | |
26 | ||
27 | struct AioHandler { | |
28 | EventNotifier *e; | |
29 | IOHandler *io_read; | |
30 | IOHandler *io_write; | |
31 | EventNotifierHandler *io_notify; | |
32 | GPollFD pfd; | |
33 | int deleted; | |
34 | void *opaque; | |
35 | QLIST_ENTRY(AioHandler) node; | |
36 | }; | |
37 | ||
38 | static void aio_remove_fd_handler(AioContext *ctx, AioHandler *node) | |
39 | { | |
40 | /* | |
41 | * If the GSource is in the process of being destroyed then | |
42 | * g_source_remove_poll() causes an assertion failure. Skip | |
43 | * removal in that case, because glib cleans up its state during | |
44 | * destruction anyway. | |
45 | */ | |
46 | if (!g_source_is_destroyed(&ctx->source)) { | |
47 | g_source_remove_poll(&ctx->source, &node->pfd); | |
48 | } | |
49 | ||
50 | /* If aio_poll is in progress, just mark the node as deleted */ | |
51 | if (qemu_lockcnt_count(&ctx->list_lock)) { | |
52 | node->deleted = 1; | |
53 | node->pfd.revents = 0; | |
54 | } else { | |
55 | /* Otherwise, delete it for real. We can't just mark it as | |
56 | * deleted because deleted nodes are only cleaned up after | |
57 | * releasing the list_lock. | |
58 | */ | |
59 | QLIST_REMOVE(node, node); | |
60 | g_free(node); | |
61 | } | |
62 | } | |
63 | ||
64 | void aio_set_fd_handler(AioContext *ctx, | |
65 | int fd, | |
66 | IOHandler *io_read, | |
67 | IOHandler *io_write, | |
68 | AioPollFn *io_poll, | |
69 | IOHandler *io_poll_ready, | |
70 | void *opaque) | |
71 | { | |
72 | AioHandler *old_node; | |
73 | AioHandler *node = NULL; | |
74 | SOCKET s; | |
75 | ||
76 | if (!fd_is_socket(fd)) { | |
77 | error_report("fd=%d is not a socket, AIO implementation is missing", fd); | |
78 | return; | |
79 | } | |
80 | ||
81 | s = _get_osfhandle(fd); | |
82 | ||
83 | qemu_lockcnt_lock(&ctx->list_lock); | |
84 | QLIST_FOREACH(old_node, &ctx->aio_handlers, node) { | |
85 | if (old_node->pfd.fd == s && !old_node->deleted) { | |
86 | break; | |
87 | } | |
88 | } | |
89 | ||
90 | if (io_read || io_write) { | |
91 | HANDLE event; | |
92 | long bitmask = 0; | |
93 | ||
94 | /* Alloc and insert if it's not already there */ | |
95 | node = g_new0(AioHandler, 1); | |
96 | node->pfd.fd = s; | |
97 | ||
98 | node->pfd.events = 0; | |
99 | if (node->io_read) { | |
100 | node->pfd.events |= G_IO_IN; | |
101 | } | |
102 | if (node->io_write) { | |
103 | node->pfd.events |= G_IO_OUT; | |
104 | } | |
105 | ||
106 | node->e = &ctx->notifier; | |
107 | ||
108 | /* Update handler with latest information */ | |
109 | node->opaque = opaque; | |
110 | node->io_read = io_read; | |
111 | node->io_write = io_write; | |
112 | ||
113 | if (io_read) { | |
114 | bitmask |= FD_READ | FD_ACCEPT | FD_CLOSE; | |
115 | } | |
116 | ||
117 | if (io_write) { | |
118 | bitmask |= FD_WRITE | FD_CONNECT; | |
119 | } | |
120 | ||
121 | QLIST_INSERT_HEAD_RCU(&ctx->aio_handlers, node, node); | |
122 | event = event_notifier_get_handle(&ctx->notifier); | |
123 | qemu_socket_select(fd, event, bitmask, NULL); | |
124 | } | |
125 | if (old_node) { | |
126 | aio_remove_fd_handler(ctx, old_node); | |
127 | } | |
128 | ||
129 | qemu_lockcnt_unlock(&ctx->list_lock); | |
130 | aio_notify(ctx); | |
131 | } | |
132 | ||
133 | void aio_set_event_notifier(AioContext *ctx, | |
134 | EventNotifier *e, | |
135 | EventNotifierHandler *io_notify, | |
136 | AioPollFn *io_poll, | |
137 | EventNotifierHandler *io_poll_ready) | |
138 | { | |
139 | AioHandler *node; | |
140 | ||
141 | qemu_lockcnt_lock(&ctx->list_lock); | |
142 | QLIST_FOREACH(node, &ctx->aio_handlers, node) { | |
143 | if (node->e == e && !node->deleted) { | |
144 | break; | |
145 | } | |
146 | } | |
147 | ||
148 | /* Are we deleting the fd handler? */ | |
149 | if (!io_notify) { | |
150 | if (node) { | |
151 | aio_remove_fd_handler(ctx, node); | |
152 | } | |
153 | } else { | |
154 | if (node == NULL) { | |
155 | /* Alloc and insert if it's not already there */ | |
156 | node = g_new0(AioHandler, 1); | |
157 | node->e = e; | |
158 | node->pfd.fd = (uintptr_t)event_notifier_get_handle(e); | |
159 | node->pfd.events = G_IO_IN; | |
160 | QLIST_INSERT_HEAD_RCU(&ctx->aio_handlers, node, node); | |
161 | ||
162 | g_source_add_poll(&ctx->source, &node->pfd); | |
163 | } | |
164 | /* Update handler with latest information */ | |
165 | node->io_notify = io_notify; | |
166 | } | |
167 | ||
168 | qemu_lockcnt_unlock(&ctx->list_lock); | |
169 | aio_notify(ctx); | |
170 | } | |
171 | ||
172 | void aio_set_event_notifier_poll(AioContext *ctx, | |
173 | EventNotifier *notifier, | |
174 | EventNotifierHandler *io_poll_begin, | |
175 | EventNotifierHandler *io_poll_end) | |
176 | { | |
177 | /* Not implemented */ | |
178 | } | |
179 | ||
180 | bool aio_prepare(AioContext *ctx) | |
181 | { | |
182 | static struct timeval tv0; | |
183 | AioHandler *node; | |
184 | bool have_select_revents = false; | |
185 | fd_set rfds, wfds; | |
186 | ||
187 | /* | |
188 | * We have to walk very carefully in case aio_set_fd_handler is | |
189 | * called while we're walking. | |
190 | */ | |
191 | qemu_lockcnt_inc(&ctx->list_lock); | |
192 | ||
193 | /* fill fd sets */ | |
194 | FD_ZERO(&rfds); | |
195 | FD_ZERO(&wfds); | |
196 | QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) { | |
197 | if (node->io_read) { | |
198 | FD_SET ((SOCKET)node->pfd.fd, &rfds); | |
199 | } | |
200 | if (node->io_write) { | |
201 | FD_SET ((SOCKET)node->pfd.fd, &wfds); | |
202 | } | |
203 | } | |
204 | ||
205 | if (select(0, &rfds, &wfds, NULL, &tv0) > 0) { | |
206 | QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) { | |
207 | node->pfd.revents = 0; | |
208 | if (FD_ISSET(node->pfd.fd, &rfds)) { | |
209 | node->pfd.revents |= G_IO_IN; | |
210 | have_select_revents = true; | |
211 | } | |
212 | ||
213 | if (FD_ISSET(node->pfd.fd, &wfds)) { | |
214 | node->pfd.revents |= G_IO_OUT; | |
215 | have_select_revents = true; | |
216 | } | |
217 | } | |
218 | } | |
219 | ||
220 | qemu_lockcnt_dec(&ctx->list_lock); | |
221 | return have_select_revents; | |
222 | } | |
223 | ||
224 | bool aio_pending(AioContext *ctx) | |
225 | { | |
226 | AioHandler *node; | |
227 | bool result = false; | |
228 | ||
229 | /* | |
230 | * We have to walk very carefully in case aio_set_fd_handler is | |
231 | * called while we're walking. | |
232 | */ | |
233 | qemu_lockcnt_inc(&ctx->list_lock); | |
234 | QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) { | |
235 | if (node->pfd.revents && node->io_notify) { | |
236 | result = true; | |
237 | break; | |
238 | } | |
239 | ||
240 | if ((node->pfd.revents & G_IO_IN) && node->io_read) { | |
241 | result = true; | |
242 | break; | |
243 | } | |
244 | if ((node->pfd.revents & G_IO_OUT) && node->io_write) { | |
245 | result = true; | |
246 | break; | |
247 | } | |
248 | } | |
249 | ||
250 | qemu_lockcnt_dec(&ctx->list_lock); | |
251 | return result; | |
252 | } | |
253 | ||
254 | static bool aio_dispatch_handlers(AioContext *ctx, HANDLE event) | |
255 | { | |
256 | AioHandler *node; | |
257 | bool progress = false; | |
258 | AioHandler *tmp; | |
259 | ||
260 | /* | |
261 | * We have to walk very carefully in case aio_set_fd_handler is | |
262 | * called while we're walking. | |
263 | */ | |
264 | QLIST_FOREACH_SAFE_RCU(node, &ctx->aio_handlers, node, tmp) { | |
265 | int revents = node->pfd.revents; | |
266 | ||
267 | if (!node->deleted && | |
268 | (revents || event_notifier_get_handle(node->e) == event) && | |
269 | node->io_notify) { | |
270 | node->pfd.revents = 0; | |
271 | node->io_notify(node->e); | |
272 | ||
273 | /* aio_notify() does not count as progress */ | |
274 | if (node->e != &ctx->notifier) { | |
275 | progress = true; | |
276 | } | |
277 | } | |
278 | ||
279 | if (!node->deleted && | |
280 | (node->io_read || node->io_write)) { | |
281 | node->pfd.revents = 0; | |
282 | if ((revents & G_IO_IN) && node->io_read) { | |
283 | node->io_read(node->opaque); | |
284 | progress = true; | |
285 | } | |
286 | if ((revents & G_IO_OUT) && node->io_write) { | |
287 | node->io_write(node->opaque); | |
288 | progress = true; | |
289 | } | |
290 | ||
291 | /* if the next select() will return an event, we have progressed */ | |
292 | if (event == event_notifier_get_handle(&ctx->notifier)) { | |
293 | WSANETWORKEVENTS ev; | |
294 | WSAEnumNetworkEvents(node->pfd.fd, event, &ev); | |
295 | if (ev.lNetworkEvents) { | |
296 | progress = true; | |
297 | } | |
298 | } | |
299 | } | |
300 | ||
301 | if (node->deleted) { | |
302 | if (qemu_lockcnt_dec_if_lock(&ctx->list_lock)) { | |
303 | QLIST_REMOVE(node, node); | |
304 | g_free(node); | |
305 | qemu_lockcnt_inc_and_unlock(&ctx->list_lock); | |
306 | } | |
307 | } | |
308 | } | |
309 | ||
310 | return progress; | |
311 | } | |
312 | ||
313 | void aio_dispatch(AioContext *ctx) | |
314 | { | |
315 | qemu_lockcnt_inc(&ctx->list_lock); | |
316 | aio_bh_poll(ctx); | |
317 | aio_dispatch_handlers(ctx, INVALID_HANDLE_VALUE); | |
318 | qemu_lockcnt_dec(&ctx->list_lock); | |
319 | timerlistgroup_run_timers(&ctx->tlg); | |
320 | } | |
321 | ||
322 | bool aio_poll(AioContext *ctx, bool blocking) | |
323 | { | |
324 | AioHandler *node; | |
325 | HANDLE events[MAXIMUM_WAIT_OBJECTS]; | |
326 | bool progress, have_select_revents, first; | |
327 | unsigned count; | |
328 | int timeout; | |
329 | ||
330 | /* | |
331 | * There cannot be two concurrent aio_poll calls for the same AioContext (or | |
332 | * an aio_poll concurrent with a GSource prepare/check/dispatch callback). | |
333 | * We rely on this below to avoid slow locked accesses to ctx->notify_me. | |
334 | * | |
335 | * aio_poll() may only be called in the AioContext's thread. iohandler_ctx | |
336 | * is special in that it runs in the main thread, but that thread's context | |
337 | * is qemu_aio_context. | |
338 | */ | |
339 | assert(in_aio_context_home_thread(ctx == iohandler_get_aio_context() ? | |
340 | qemu_get_aio_context() : ctx)); | |
341 | progress = false; | |
342 | ||
343 | /* aio_notify can avoid the expensive event_notifier_set if | |
344 | * everything (file descriptors, bottom halves, timers) will | |
345 | * be re-evaluated before the next blocking poll(). This is | |
346 | * already true when aio_poll is called with blocking == false; | |
347 | * if blocking == true, it is only true after poll() returns, | |
348 | * so disable the optimization now. | |
349 | */ | |
350 | if (blocking) { | |
351 | qatomic_set(&ctx->notify_me, qatomic_read(&ctx->notify_me) + 2); | |
352 | /* | |
353 | * Write ctx->notify_me before computing the timeout | |
354 | * (reading bottom half flags, etc.). Pairs with | |
355 | * smp_mb in aio_notify(). | |
356 | */ | |
357 | smp_mb(); | |
358 | } | |
359 | ||
360 | qemu_lockcnt_inc(&ctx->list_lock); | |
361 | have_select_revents = aio_prepare(ctx); | |
362 | ||
363 | /* fill fd sets */ | |
364 | count = 0; | |
365 | QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) { | |
366 | if (!node->deleted && node->io_notify) { | |
367 | assert(count < MAXIMUM_WAIT_OBJECTS); | |
368 | events[count++] = event_notifier_get_handle(node->e); | |
369 | } | |
370 | } | |
371 | ||
372 | first = true; | |
373 | ||
374 | /* ctx->notifier is always registered. */ | |
375 | assert(count > 0); | |
376 | ||
377 | /* Multiple iterations, all of them non-blocking except the first, | |
378 | * may be necessary to process all pending events. After the first | |
379 | * WaitForMultipleObjects call ctx->notify_me will be decremented. | |
380 | */ | |
381 | do { | |
382 | HANDLE event; | |
383 | int ret; | |
384 | ||
385 | timeout = blocking && !have_select_revents | |
386 | ? qemu_timeout_ns_to_ms(aio_compute_timeout(ctx)) : 0; | |
387 | ret = WaitForMultipleObjects(count, events, FALSE, timeout); | |
388 | if (blocking) { | |
389 | assert(first); | |
390 | qatomic_store_release(&ctx->notify_me, | |
391 | qatomic_read(&ctx->notify_me) - 2); | |
392 | aio_notify_accept(ctx); | |
393 | } | |
394 | ||
395 | if (first) { | |
396 | progress |= aio_bh_poll(ctx); | |
397 | first = false; | |
398 | } | |
399 | ||
400 | /* if we have any signaled events, dispatch event */ | |
401 | event = NULL; | |
402 | if ((DWORD) (ret - WAIT_OBJECT_0) < count) { | |
403 | event = events[ret - WAIT_OBJECT_0]; | |
404 | events[ret - WAIT_OBJECT_0] = events[--count]; | |
405 | } else if (!have_select_revents) { | |
406 | break; | |
407 | } | |
408 | ||
409 | have_select_revents = false; | |
410 | blocking = false; | |
411 | ||
412 | progress |= aio_dispatch_handlers(ctx, event); | |
413 | } while (count > 0); | |
414 | ||
415 | qemu_lockcnt_dec(&ctx->list_lock); | |
416 | ||
417 | progress |= timerlistgroup_run_timers(&ctx->tlg); | |
418 | return progress; | |
419 | } | |
420 | ||
421 | void aio_context_setup(AioContext *ctx) | |
422 | { | |
423 | } | |
424 | ||
425 | void aio_context_destroy(AioContext *ctx) | |
426 | { | |
427 | } | |
428 | ||
429 | void aio_context_use_g_source(AioContext *ctx) | |
430 | { | |
431 | } | |
432 | ||
433 | void aio_context_set_poll_params(AioContext *ctx, int64_t max_ns, | |
434 | int64_t grow, int64_t shrink, Error **errp) | |
435 | { | |
436 | if (max_ns) { | |
437 | error_setg(errp, "AioContext polling is not implemented on Windows"); | |
438 | } | |
439 | } | |
440 | ||
441 | void aio_context_set_aio_params(AioContext *ctx, int64_t max_batch, | |
442 | Error **errp) | |
443 | { | |
444 | } |