pseries: Switch VGA endian on H_SET_MODE
[qemu/ar7.git] / async.c
blob2be88cc9e9a28093937423fc7e39474c0cd825bb
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-common.h"
26 #include "block/aio.h"
27 #include "block/thread-pool.h"
28 #include "qemu/main-loop.h"
29 #include "qemu/atomic.h"
31 /***********************************************************/
32 /* bottom halves (can be seen as timers which expire ASAP) */
34 struct QEMUBH {
35 AioContext *ctx;
36 QEMUBHFunc *cb;
37 void *opaque;
38 QEMUBH *next;
39 bool scheduled;
40 bool idle;
41 bool deleted;
44 QEMUBH *aio_bh_new(AioContext *ctx, QEMUBHFunc *cb, void *opaque)
46 QEMUBH *bh;
47 bh = g_new(QEMUBH, 1);
48 *bh = (QEMUBH){
49 .ctx = ctx,
50 .cb = cb,
51 .opaque = opaque,
53 qemu_mutex_lock(&ctx->bh_lock);
54 bh->next = ctx->first_bh;
55 /* Make sure that the members are ready before putting bh into list */
56 smp_wmb();
57 ctx->first_bh = bh;
58 qemu_mutex_unlock(&ctx->bh_lock);
59 return bh;
62 /* Multiple occurrences of aio_bh_poll cannot be called concurrently */
63 int aio_bh_poll(AioContext *ctx)
65 QEMUBH *bh, **bhp, *next;
66 int ret;
68 ctx->walking_bh++;
70 ret = 0;
71 for (bh = ctx->first_bh; bh; bh = next) {
72 /* Make sure that fetching bh happens before accessing its members */
73 smp_read_barrier_depends();
74 next = bh->next;
75 if (!bh->deleted && bh->scheduled) {
76 bh->scheduled = 0;
77 /* Paired with write barrier in bh schedule to ensure reading for
78 * idle & callbacks coming after bh's scheduling.
80 smp_rmb();
81 if (!bh->idle)
82 ret = 1;
83 bh->idle = 0;
84 bh->cb(bh->opaque);
88 ctx->walking_bh--;
90 /* remove deleted bhs */
91 if (!ctx->walking_bh) {
92 qemu_mutex_lock(&ctx->bh_lock);
93 bhp = &ctx->first_bh;
94 while (*bhp) {
95 bh = *bhp;
96 if (bh->deleted) {
97 *bhp = bh->next;
98 g_free(bh);
99 } else {
100 bhp = &bh->next;
103 qemu_mutex_unlock(&ctx->bh_lock);
106 return ret;
109 void qemu_bh_schedule_idle(QEMUBH *bh)
111 if (bh->scheduled)
112 return;
113 bh->idle = 1;
114 /* Make sure that idle & any writes needed by the callback are done
115 * before the locations are read in the aio_bh_poll.
117 smp_wmb();
118 bh->scheduled = 1;
121 void qemu_bh_schedule(QEMUBH *bh)
123 AioContext *ctx;
125 if (bh->scheduled)
126 return;
127 ctx = bh->ctx;
128 bh->idle = 0;
129 /* Make sure that:
130 * 1. idle & any writes needed by the callback are done before the
131 * locations are read in the aio_bh_poll.
132 * 2. ctx is loaded before scheduled is set and the callback has a chance
133 * to execute.
135 smp_mb();
136 bh->scheduled = 1;
137 aio_notify(ctx);
141 /* This func is async.
143 void qemu_bh_cancel(QEMUBH *bh)
145 bh->scheduled = 0;
148 /* This func is async.The bottom half will do the delete action at the finial
149 * end.
151 void qemu_bh_delete(QEMUBH *bh)
153 bh->scheduled = 0;
154 bh->deleted = 1;
157 int64_t
158 aio_compute_timeout(AioContext *ctx)
160 int64_t deadline;
161 int timeout = -1;
162 QEMUBH *bh;
164 for (bh = ctx->first_bh; bh; bh = bh->next) {
165 if (!bh->deleted && bh->scheduled) {
166 if (bh->idle) {
167 /* idle bottom halves will be polled at least
168 * every 10ms */
169 timeout = 10000000;
170 } else {
171 /* non-idle bottom halves will be executed
172 * immediately */
173 return 0;
178 deadline = timerlistgroup_deadline_ns(&ctx->tlg);
179 if (deadline == 0) {
180 return 0;
181 } else {
182 return qemu_soonest_timeout(timeout, deadline);
186 static gboolean
187 aio_ctx_prepare(GSource *source, gint *timeout)
189 AioContext *ctx = (AioContext *) source;
191 /* We assume there is no timeout already supplied */
192 *timeout = qemu_timeout_ns_to_ms(aio_compute_timeout(ctx));
194 if (aio_prepare(ctx)) {
195 *timeout = 0;
198 return *timeout == 0;
201 static gboolean
202 aio_ctx_check(GSource *source)
204 AioContext *ctx = (AioContext *) source;
205 QEMUBH *bh;
207 for (bh = ctx->first_bh; bh; bh = bh->next) {
208 if (!bh->deleted && bh->scheduled) {
209 return true;
212 return aio_pending(ctx) || (timerlistgroup_deadline_ns(&ctx->tlg) == 0);
215 static gboolean
216 aio_ctx_dispatch(GSource *source,
217 GSourceFunc callback,
218 gpointer user_data)
220 AioContext *ctx = (AioContext *) source;
222 assert(callback == NULL);
223 aio_dispatch(ctx);
224 return true;
227 static void
228 aio_ctx_finalize(GSource *source)
230 AioContext *ctx = (AioContext *) source;
232 thread_pool_free(ctx->thread_pool);
233 aio_set_event_notifier(ctx, &ctx->notifier, NULL);
234 event_notifier_cleanup(&ctx->notifier);
235 rfifolock_destroy(&ctx->lock);
236 qemu_mutex_destroy(&ctx->bh_lock);
237 g_array_free(ctx->pollfds, TRUE);
238 timerlistgroup_deinit(&ctx->tlg);
241 static GSourceFuncs aio_source_funcs = {
242 aio_ctx_prepare,
243 aio_ctx_check,
244 aio_ctx_dispatch,
245 aio_ctx_finalize
248 GSource *aio_get_g_source(AioContext *ctx)
250 g_source_ref(&ctx->source);
251 return &ctx->source;
254 ThreadPool *aio_get_thread_pool(AioContext *ctx)
256 if (!ctx->thread_pool) {
257 ctx->thread_pool = thread_pool_new(ctx);
259 return ctx->thread_pool;
262 void aio_set_dispatching(AioContext *ctx, bool dispatching)
264 ctx->dispatching = dispatching;
265 if (!dispatching) {
266 /* Write ctx->dispatching before reading e.g. bh->scheduled.
267 * Optimization: this is only needed when we're entering the "unsafe"
268 * phase where other threads must call event_notifier_set.
270 smp_mb();
274 void aio_notify(AioContext *ctx)
276 /* Write e.g. bh->scheduled before reading ctx->dispatching. */
277 smp_mb();
278 if (!ctx->dispatching) {
279 event_notifier_set(&ctx->notifier);
283 static void aio_timerlist_notify(void *opaque)
285 aio_notify(opaque);
288 static void aio_rfifolock_cb(void *opaque)
290 /* Kick owner thread in case they are blocked in aio_poll() */
291 aio_notify(opaque);
294 AioContext *aio_context_new(Error **errp)
296 int ret;
297 AioContext *ctx;
298 ctx = (AioContext *) g_source_new(&aio_source_funcs, sizeof(AioContext));
299 ret = event_notifier_init(&ctx->notifier, false);
300 if (ret < 0) {
301 g_source_destroy(&ctx->source);
302 error_setg_errno(errp, -ret, "Failed to initialize event notifier");
303 return NULL;
305 g_source_set_can_recurse(&ctx->source, true);
306 aio_set_event_notifier(ctx, &ctx->notifier,
307 (EventNotifierHandler *)
308 event_notifier_test_and_clear);
309 ctx->pollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD));
310 ctx->thread_pool = NULL;
311 qemu_mutex_init(&ctx->bh_lock);
312 rfifolock_init(&ctx->lock, aio_rfifolock_cb, ctx);
313 timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx);
315 return ctx;
318 void aio_context_ref(AioContext *ctx)
320 g_source_ref(&ctx->source);
323 void aio_context_unref(AioContext *ctx)
325 g_source_unref(&ctx->source);
328 void aio_context_acquire(AioContext *ctx)
330 rfifolock_lock(&ctx->lock);
333 void aio_context_release(AioContext *ctx)
335 rfifolock_unlock(&ctx->lock);