aspeed: extend the number of host SPI controllers
[qemu/ar7.git] / async.c
blobf30d011ebc0dc4601ee78ff22e03a7b7576e3cad
1 /*
2 * QEMU System Emulator
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
22 * THE SOFTWARE.
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) */
37 struct QEMUBH {
38 AioContext *ctx;
39 QEMUBHFunc *cb;
40 void *opaque;
41 QEMUBH *next;
42 bool scheduled;
43 bool idle;
44 bool deleted;
47 void aio_bh_schedule_oneshot(AioContext *ctx, QEMUBHFunc *cb, void *opaque)
49 QEMUBH *bh;
50 bh = g_new(QEMUBH, 1);
51 *bh = (QEMUBH){
52 .ctx = ctx,
53 .cb = cb,
54 .opaque = opaque,
56 qemu_mutex_lock(&ctx->bh_lock);
57 bh->next = ctx->first_bh;
58 bh->scheduled = 1;
59 bh->deleted = 1;
60 /* Make sure that the members are ready before putting bh into list */
61 smp_wmb();
62 ctx->first_bh = bh;
63 qemu_mutex_unlock(&ctx->bh_lock);
66 QEMUBH *aio_bh_new(AioContext *ctx, QEMUBHFunc *cb, void *opaque)
68 QEMUBH *bh;
69 bh = g_new(QEMUBH, 1);
70 *bh = (QEMUBH){
71 .ctx = ctx,
72 .cb = cb,
73 .opaque = opaque,
75 qemu_mutex_lock(&ctx->bh_lock);
76 bh->next = ctx->first_bh;
77 /* Make sure that the members are ready before putting bh into list */
78 smp_wmb();
79 ctx->first_bh = bh;
80 qemu_mutex_unlock(&ctx->bh_lock);
81 return bh;
84 void aio_bh_call(QEMUBH *bh)
86 bh->cb(bh->opaque);
89 /* Multiple occurrences of aio_bh_poll cannot be called concurrently */
90 int aio_bh_poll(AioContext *ctx)
92 QEMUBH *bh, **bhp, *next;
93 int ret;
95 ctx->walking_bh++;
97 ret = 0;
98 for (bh = ctx->first_bh; bh; bh = next) {
99 /* Make sure that fetching bh happens before accessing its members */
100 smp_read_barrier_depends();
101 next = bh->next;
102 /* The atomic_xchg is paired with the one in qemu_bh_schedule. The
103 * implicit memory barrier ensures that the callback sees all writes
104 * done by the scheduling thread. It also ensures that the scheduling
105 * thread sees the zero before bh->cb has run, and thus will call
106 * aio_notify again if necessary.
108 if (atomic_xchg(&bh->scheduled, 0)) {
109 /* Idle BHs and the notify BH don't count as progress */
110 if (!bh->idle && bh != ctx->notify_dummy_bh) {
111 ret = 1;
113 bh->idle = 0;
114 aio_bh_call(bh);
118 ctx->walking_bh--;
120 /* remove deleted bhs */
121 if (!ctx->walking_bh) {
122 qemu_mutex_lock(&ctx->bh_lock);
123 bhp = &ctx->first_bh;
124 while (*bhp) {
125 bh = *bhp;
126 if (bh->deleted && !bh->scheduled) {
127 *bhp = bh->next;
128 g_free(bh);
129 } else {
130 bhp = &bh->next;
133 qemu_mutex_unlock(&ctx->bh_lock);
136 return ret;
139 void qemu_bh_schedule_idle(QEMUBH *bh)
141 bh->idle = 1;
142 /* Make sure that idle & any writes needed by the callback are done
143 * before the locations are read in the aio_bh_poll.
145 atomic_mb_set(&bh->scheduled, 1);
148 void qemu_bh_schedule(QEMUBH *bh)
150 AioContext *ctx;
152 ctx = bh->ctx;
153 bh->idle = 0;
154 /* The memory barrier implicit in atomic_xchg makes sure that:
155 * 1. idle & any writes needed by the callback are done before the
156 * locations are read in the aio_bh_poll.
157 * 2. ctx is loaded before scheduled is set and the callback has a chance
158 * to execute.
160 if (atomic_xchg(&bh->scheduled, 1) == 0) {
161 aio_notify(ctx);
166 /* This func is async.
168 void qemu_bh_cancel(QEMUBH *bh)
170 bh->scheduled = 0;
173 /* This func is async.The bottom half will do the delete action at the finial
174 * end.
176 void qemu_bh_delete(QEMUBH *bh)
178 bh->scheduled = 0;
179 bh->deleted = 1;
182 int64_t
183 aio_compute_timeout(AioContext *ctx)
185 int64_t deadline;
186 int timeout = -1;
187 QEMUBH *bh;
189 for (bh = ctx->first_bh; bh; bh = bh->next) {
190 if (bh->scheduled) {
191 if (bh->idle) {
192 /* idle bottom halves will be polled at least
193 * every 10ms */
194 timeout = 10000000;
195 } else {
196 /* non-idle bottom halves will be executed
197 * immediately */
198 return 0;
203 deadline = timerlistgroup_deadline_ns(&ctx->tlg);
204 if (deadline == 0) {
205 return 0;
206 } else {
207 return qemu_soonest_timeout(timeout, deadline);
211 static gboolean
212 aio_ctx_prepare(GSource *source, gint *timeout)
214 AioContext *ctx = (AioContext *) source;
216 atomic_or(&ctx->notify_me, 1);
218 /* We assume there is no timeout already supplied */
219 *timeout = qemu_timeout_ns_to_ms(aio_compute_timeout(ctx));
221 if (aio_prepare(ctx)) {
222 *timeout = 0;
225 return *timeout == 0;
228 static gboolean
229 aio_ctx_check(GSource *source)
231 AioContext *ctx = (AioContext *) source;
232 QEMUBH *bh;
234 atomic_and(&ctx->notify_me, ~1);
235 aio_notify_accept(ctx);
237 for (bh = ctx->first_bh; bh; bh = bh->next) {
238 if (bh->scheduled) {
239 return true;
242 return aio_pending(ctx) || (timerlistgroup_deadline_ns(&ctx->tlg) == 0);
245 static gboolean
246 aio_ctx_dispatch(GSource *source,
247 GSourceFunc callback,
248 gpointer user_data)
250 AioContext *ctx = (AioContext *) source;
252 assert(callback == NULL);
253 aio_dispatch(ctx);
254 return true;
257 static void
258 aio_ctx_finalize(GSource *source)
260 AioContext *ctx = (AioContext *) source;
262 qemu_bh_delete(ctx->notify_dummy_bh);
263 thread_pool_free(ctx->thread_pool);
265 #ifdef CONFIG_LINUX_AIO
266 if (ctx->linux_aio) {
267 laio_detach_aio_context(ctx->linux_aio, ctx);
268 laio_cleanup(ctx->linux_aio);
269 ctx->linux_aio = NULL;
271 #endif
273 qemu_mutex_lock(&ctx->bh_lock);
274 while (ctx->first_bh) {
275 QEMUBH *next = ctx->first_bh->next;
277 /* qemu_bh_delete() must have been called on BHs in this AioContext */
278 assert(ctx->first_bh->deleted);
280 g_free(ctx->first_bh);
281 ctx->first_bh = next;
283 qemu_mutex_unlock(&ctx->bh_lock);
285 aio_set_event_notifier(ctx, &ctx->notifier, false, NULL);
286 event_notifier_cleanup(&ctx->notifier);
287 rfifolock_destroy(&ctx->lock);
288 qemu_mutex_destroy(&ctx->bh_lock);
289 timerlistgroup_deinit(&ctx->tlg);
292 static GSourceFuncs aio_source_funcs = {
293 aio_ctx_prepare,
294 aio_ctx_check,
295 aio_ctx_dispatch,
296 aio_ctx_finalize
299 GSource *aio_get_g_source(AioContext *ctx)
301 g_source_ref(&ctx->source);
302 return &ctx->source;
305 ThreadPool *aio_get_thread_pool(AioContext *ctx)
307 if (!ctx->thread_pool) {
308 ctx->thread_pool = thread_pool_new(ctx);
310 return ctx->thread_pool;
313 #ifdef CONFIG_LINUX_AIO
314 LinuxAioState *aio_get_linux_aio(AioContext *ctx)
316 if (!ctx->linux_aio) {
317 ctx->linux_aio = laio_init();
318 laio_attach_aio_context(ctx->linux_aio, ctx);
320 return ctx->linux_aio;
322 #endif
324 void aio_notify(AioContext *ctx)
326 /* Write e.g. bh->scheduled before reading ctx->notify_me. Pairs
327 * with atomic_or in aio_ctx_prepare or atomic_add in aio_poll.
329 smp_mb();
330 if (ctx->notify_me) {
331 event_notifier_set(&ctx->notifier);
332 atomic_mb_set(&ctx->notified, true);
336 void aio_notify_accept(AioContext *ctx)
338 if (atomic_xchg(&ctx->notified, false)) {
339 event_notifier_test_and_clear(&ctx->notifier);
343 static void aio_timerlist_notify(void *opaque)
345 aio_notify(opaque);
348 static void aio_rfifolock_cb(void *opaque)
350 AioContext *ctx = opaque;
352 /* Kick owner thread in case they are blocked in aio_poll() */
353 qemu_bh_schedule(ctx->notify_dummy_bh);
356 static void notify_dummy_bh(void *opaque)
358 /* Do nothing, we were invoked just to force the event loop to iterate */
361 static void event_notifier_dummy_cb(EventNotifier *e)
365 AioContext *aio_context_new(Error **errp)
367 int ret;
368 AioContext *ctx;
370 ctx = (AioContext *) g_source_new(&aio_source_funcs, sizeof(AioContext));
371 aio_context_setup(ctx);
373 ret = event_notifier_init(&ctx->notifier, false);
374 if (ret < 0) {
375 error_setg_errno(errp, -ret, "Failed to initialize event notifier");
376 goto fail;
378 g_source_set_can_recurse(&ctx->source, true);
379 aio_set_event_notifier(ctx, &ctx->notifier,
380 false,
381 (EventNotifierHandler *)
382 event_notifier_dummy_cb);
383 #ifdef CONFIG_LINUX_AIO
384 ctx->linux_aio = NULL;
385 #endif
386 ctx->thread_pool = NULL;
387 qemu_mutex_init(&ctx->bh_lock);
388 rfifolock_init(&ctx->lock, aio_rfifolock_cb, ctx);
389 timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx);
391 ctx->notify_dummy_bh = aio_bh_new(ctx, notify_dummy_bh, NULL);
393 return ctx;
394 fail:
395 g_source_destroy(&ctx->source);
396 return NULL;
399 void aio_context_ref(AioContext *ctx)
401 g_source_ref(&ctx->source);
404 void aio_context_unref(AioContext *ctx)
406 g_source_unref(&ctx->source);
409 void aio_context_acquire(AioContext *ctx)
411 rfifolock_lock(&ctx->lock);
414 void aio_context_release(AioContext *ctx)
416 rfifolock_unlock(&ctx->lock);