4 * Copyright (c) 2003-2008 Fabrice Bellard
6 * Permission is hereby granted, free of charge, to any person obtaining a copy
7 * of this software and associated documentation files (the "Software"), to deal
8 * in the Software without restriction, including without limitation the rights
9 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
10 * copies of the Software, and to permit persons to whom the Software is
11 * furnished to do so, subject to the following conditions:
13 * The above copyright notice and this permission notice shall be included in
14 * all copies or substantial portions of the Software.
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
25 #include "qemu/osdep.h"
26 #include "qapi/error.h"
27 #include "qemu-common.h"
28 #include "block/aio.h"
29 #include "block/thread-pool.h"
30 #include "qemu/main-loop.h"
31 #include "qemu/atomic.h"
32 #include "block/raw-aio.h"
34 /***********************************************************/
35 /* bottom halves (can be seen as timers which expire ASAP) */
47 void aio_bh_schedule_oneshot(AioContext *ctx, QEMUBHFunc *cb, void *opaque)
50 bh = g_new(QEMUBH, 1);
56 qemu_mutex_lock(&ctx->bh_lock);
57 bh->next = ctx->first_bh;
60 /* Make sure that the members are ready before putting bh into list */
63 qemu_mutex_unlock(&ctx->bh_lock);
67 QEMUBH *aio_bh_new(AioContext *ctx, QEMUBHFunc *cb, void *opaque)
70 bh = g_new(QEMUBH, 1);
76 qemu_mutex_lock(&ctx->bh_lock);
77 bh->next = ctx->first_bh;
78 /* Make sure that the members are ready before putting bh into list */
81 qemu_mutex_unlock(&ctx->bh_lock);
85 void aio_bh_call(QEMUBH *bh)
90 /* Multiple occurrences of aio_bh_poll cannot be called concurrently */
91 int aio_bh_poll(AioContext *ctx)
93 QEMUBH *bh, **bhp, *next;
99 for (bh = ctx->first_bh; bh; bh = next) {
100 /* Make sure that fetching bh happens before accessing its members */
101 smp_read_barrier_depends();
103 /* The atomic_xchg is paired with the one in qemu_bh_schedule. The
104 * implicit memory barrier ensures that the callback sees all writes
105 * done by the scheduling thread. It also ensures that the scheduling
106 * thread sees the zero before bh->cb has run, and thus will call
107 * aio_notify again if necessary.
109 if (atomic_xchg(&bh->scheduled, 0)) {
110 /* Idle BHs and the notify BH don't count as progress */
111 if (!bh->idle && bh != ctx->notify_dummy_bh) {
121 /* remove deleted bhs */
122 if (!ctx->walking_bh) {
123 qemu_mutex_lock(&ctx->bh_lock);
124 bhp = &ctx->first_bh;
127 if (bh->deleted && !bh->scheduled) {
134 qemu_mutex_unlock(&ctx->bh_lock);
140 void qemu_bh_schedule_idle(QEMUBH *bh)
143 /* Make sure that idle & any writes needed by the callback are done
144 * before the locations are read in the aio_bh_poll.
146 atomic_mb_set(&bh->scheduled, 1);
149 void qemu_bh_schedule(QEMUBH *bh)
155 /* The memory barrier implicit in atomic_xchg makes sure that:
156 * 1. idle & any writes needed by the callback are done before the
157 * locations are read in the aio_bh_poll.
158 * 2. ctx is loaded before scheduled is set and the callback has a chance
161 if (atomic_xchg(&bh->scheduled, 1) == 0) {
167 /* This func is async.
169 void qemu_bh_cancel(QEMUBH *bh)
174 /* This func is async.The bottom half will do the delete action at the finial
177 void qemu_bh_delete(QEMUBH *bh)
184 aio_compute_timeout(AioContext *ctx)
190 for (bh = ctx->first_bh; bh; bh = bh->next) {
193 /* idle bottom halves will be polled at least
197 /* non-idle bottom halves will be executed
204 deadline = timerlistgroup_deadline_ns(&ctx->tlg);
208 return qemu_soonest_timeout(timeout, deadline);
213 aio_ctx_prepare(GSource *source, gint *timeout)
215 AioContext *ctx = (AioContext *) source;
217 atomic_or(&ctx->notify_me, 1);
219 /* We assume there is no timeout already supplied */
220 *timeout = qemu_timeout_ns_to_ms(aio_compute_timeout(ctx));
222 if (aio_prepare(ctx)) {
226 return *timeout == 0;
230 aio_ctx_check(GSource *source)
232 AioContext *ctx = (AioContext *) source;
235 atomic_and(&ctx->notify_me, ~1);
236 aio_notify_accept(ctx);
238 for (bh = ctx->first_bh; bh; bh = bh->next) {
243 return aio_pending(ctx) || (timerlistgroup_deadline_ns(&ctx->tlg) == 0);
247 aio_ctx_dispatch(GSource *source,
248 GSourceFunc callback,
251 AioContext *ctx = (AioContext *) source;
253 assert(callback == NULL);
259 aio_ctx_finalize(GSource *source)
261 AioContext *ctx = (AioContext *) source;
263 qemu_bh_delete(ctx->notify_dummy_bh);
264 thread_pool_free(ctx->thread_pool);
266 #ifdef CONFIG_LINUX_AIO
267 if (ctx->linux_aio) {
268 laio_detach_aio_context(ctx->linux_aio, ctx);
269 laio_cleanup(ctx->linux_aio);
270 ctx->linux_aio = NULL;
274 qemu_mutex_lock(&ctx->bh_lock);
275 while (ctx->first_bh) {
276 QEMUBH *next = ctx->first_bh->next;
278 /* qemu_bh_delete() must have been called on BHs in this AioContext */
279 assert(ctx->first_bh->deleted);
281 g_free(ctx->first_bh);
282 ctx->first_bh = next;
284 qemu_mutex_unlock(&ctx->bh_lock);
286 aio_set_event_notifier(ctx, &ctx->notifier, false, NULL);
287 event_notifier_cleanup(&ctx->notifier);
288 rfifolock_destroy(&ctx->lock);
289 qemu_mutex_destroy(&ctx->bh_lock);
290 timerlistgroup_deinit(&ctx->tlg);
293 static GSourceFuncs aio_source_funcs = {
300 GSource *aio_get_g_source(AioContext *ctx)
302 g_source_ref(&ctx->source);
306 ThreadPool *aio_get_thread_pool(AioContext *ctx)
308 if (!ctx->thread_pool) {
309 ctx->thread_pool = thread_pool_new(ctx);
311 return ctx->thread_pool;
314 #ifdef CONFIG_LINUX_AIO
315 LinuxAioState *aio_get_linux_aio(AioContext *ctx)
317 if (!ctx->linux_aio) {
318 ctx->linux_aio = laio_init();
319 laio_attach_aio_context(ctx->linux_aio, ctx);
321 return ctx->linux_aio;
325 void aio_notify(AioContext *ctx)
327 /* Write e.g. bh->scheduled before reading ctx->notify_me. Pairs
328 * with atomic_or in aio_ctx_prepare or atomic_add in aio_poll.
331 if (ctx->notify_me) {
332 event_notifier_set(&ctx->notifier);
333 atomic_mb_set(&ctx->notified, true);
337 void aio_notify_accept(AioContext *ctx)
339 if (atomic_xchg(&ctx->notified, false)) {
340 event_notifier_test_and_clear(&ctx->notifier);
344 static void aio_timerlist_notify(void *opaque)
349 static void aio_rfifolock_cb(void *opaque)
351 AioContext *ctx = opaque;
353 /* Kick owner thread in case they are blocked in aio_poll() */
354 qemu_bh_schedule(ctx->notify_dummy_bh);
357 static void notify_dummy_bh(void *opaque)
359 /* Do nothing, we were invoked just to force the event loop to iterate */
362 static void event_notifier_dummy_cb(EventNotifier *e)
366 AioContext *aio_context_new(Error **errp)
371 ctx = (AioContext *) g_source_new(&aio_source_funcs, sizeof(AioContext));
372 aio_context_setup(ctx);
374 ret = event_notifier_init(&ctx->notifier, false);
376 error_setg_errno(errp, -ret, "Failed to initialize event notifier");
379 g_source_set_can_recurse(&ctx->source, true);
380 aio_set_event_notifier(ctx, &ctx->notifier,
382 (EventNotifierHandler *)
383 event_notifier_dummy_cb);
384 #ifdef CONFIG_LINUX_AIO
385 ctx->linux_aio = NULL;
387 ctx->thread_pool = NULL;
388 qemu_mutex_init(&ctx->bh_lock);
389 rfifolock_init(&ctx->lock, aio_rfifolock_cb, ctx);
390 timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx);
392 ctx->notify_dummy_bh = aio_bh_new(ctx, notify_dummy_bh, NULL);
396 g_source_destroy(&ctx->source);
400 void aio_context_ref(AioContext *ctx)
402 g_source_ref(&ctx->source);
405 void aio_context_unref(AioContext *ctx)
407 g_source_unref(&ctx->source);
410 void aio_context_acquire(AioContext *ctx)
412 rfifolock_lock(&ctx->lock);
415 void aio_context_release(AioContext *ctx)
417 rfifolock_unlock(&ctx->lock);