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1 | /* | |
2 | * QEMU System Emulator | |
3 | * | |
4 | * Copyright (c) 2003-2008 Fabrice Bellard | |
5 | * | |
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: | |
12 | * | |
13 | * The above copyright notice and this permission notice shall be included in | |
14 | * all copies or substantial portions of the Software. | |
15 | * | |
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. | |
23 | */ | |
24 | ||
25 | #include "qemu-common.h" | |
26 | #include "block/aio.h" | |
27 | #include "block/thread-pool.h" | |
28 | #include "qemu/main-loop.h" | |
29 | ||
30 | /***********************************************************/ | |
31 | /* bottom halves (can be seen as timers which expire ASAP) */ | |
32 | ||
33 | struct QEMUBH { | |
34 | AioContext *ctx; | |
35 | QEMUBHFunc *cb; | |
36 | void *opaque; | |
37 | QEMUBH *next; | |
38 | bool scheduled; | |
39 | bool idle; | |
40 | bool deleted; | |
41 | }; | |
42 | ||
43 | QEMUBH *aio_bh_new(AioContext *ctx, QEMUBHFunc *cb, void *opaque) | |
44 | { | |
45 | QEMUBH *bh; | |
46 | bh = g_malloc0(sizeof(QEMUBH)); | |
47 | bh->ctx = ctx; | |
48 | bh->cb = cb; | |
49 | bh->opaque = opaque; | |
50 | qemu_mutex_lock(&ctx->bh_lock); | |
51 | bh->next = ctx->first_bh; | |
52 | /* Make sure that the members are ready before putting bh into list */ | |
53 | smp_wmb(); | |
54 | ctx->first_bh = bh; | |
55 | qemu_mutex_unlock(&ctx->bh_lock); | |
56 | return bh; | |
57 | } | |
58 | ||
59 | /* Multiple occurrences of aio_bh_poll cannot be called concurrently */ | |
60 | int aio_bh_poll(AioContext *ctx) | |
61 | { | |
62 | QEMUBH *bh, **bhp, *next; | |
63 | int ret; | |
64 | ||
65 | ctx->walking_bh++; | |
66 | ||
67 | ret = 0; | |
68 | for (bh = ctx->first_bh; bh; bh = next) { | |
69 | /* Make sure that fetching bh happens before accessing its members */ | |
70 | smp_read_barrier_depends(); | |
71 | next = bh->next; | |
72 | if (!bh->deleted && bh->scheduled) { | |
73 | bh->scheduled = 0; | |
74 | /* Paired with write barrier in bh schedule to ensure reading for | |
75 | * idle & callbacks coming after bh's scheduling. | |
76 | */ | |
77 | smp_rmb(); | |
78 | if (!bh->idle) | |
79 | ret = 1; | |
80 | bh->idle = 0; | |
81 | bh->cb(bh->opaque); | |
82 | } | |
83 | } | |
84 | ||
85 | ctx->walking_bh--; | |
86 | ||
87 | /* remove deleted bhs */ | |
88 | if (!ctx->walking_bh) { | |
89 | qemu_mutex_lock(&ctx->bh_lock); | |
90 | bhp = &ctx->first_bh; | |
91 | while (*bhp) { | |
92 | bh = *bhp; | |
93 | if (bh->deleted) { | |
94 | *bhp = bh->next; | |
95 | g_free(bh); | |
96 | } else { | |
97 | bhp = &bh->next; | |
98 | } | |
99 | } | |
100 | qemu_mutex_unlock(&ctx->bh_lock); | |
101 | } | |
102 | ||
103 | return ret; | |
104 | } | |
105 | ||
106 | void qemu_bh_schedule_idle(QEMUBH *bh) | |
107 | { | |
108 | if (bh->scheduled) | |
109 | return; | |
110 | bh->idle = 1; | |
111 | /* Make sure that idle & any writes needed by the callback are done | |
112 | * before the locations are read in the aio_bh_poll. | |
113 | */ | |
114 | smp_wmb(); | |
115 | bh->scheduled = 1; | |
116 | } | |
117 | ||
118 | void qemu_bh_schedule(QEMUBH *bh) | |
119 | { | |
120 | if (bh->scheduled) | |
121 | return; | |
122 | bh->idle = 0; | |
123 | /* Make sure that idle & any writes needed by the callback are done | |
124 | * before the locations are read in the aio_bh_poll. | |
125 | */ | |
126 | smp_wmb(); | |
127 | bh->scheduled = 1; | |
128 | aio_notify(bh->ctx); | |
129 | } | |
130 | ||
131 | ||
132 | /* This func is async. | |
133 | */ | |
134 | void qemu_bh_cancel(QEMUBH *bh) | |
135 | { | |
136 | bh->scheduled = 0; | |
137 | } | |
138 | ||
139 | /* This func is async.The bottom half will do the delete action at the finial | |
140 | * end. | |
141 | */ | |
142 | void qemu_bh_delete(QEMUBH *bh) | |
143 | { | |
144 | bh->scheduled = 0; | |
145 | bh->deleted = 1; | |
146 | } | |
147 | ||
148 | static gboolean | |
149 | aio_ctx_prepare(GSource *source, gint *timeout) | |
150 | { | |
151 | AioContext *ctx = (AioContext *) source; | |
152 | QEMUBH *bh; | |
153 | int deadline; | |
154 | ||
155 | /* We assume there is no timeout already supplied */ | |
156 | *timeout = -1; | |
157 | for (bh = ctx->first_bh; bh; bh = bh->next) { | |
158 | if (!bh->deleted && bh->scheduled) { | |
159 | if (bh->idle) { | |
160 | /* idle bottom halves will be polled at least | |
161 | * every 10ms */ | |
162 | *timeout = 10; | |
163 | } else { | |
164 | /* non-idle bottom halves will be executed | |
165 | * immediately */ | |
166 | *timeout = 0; | |
167 | return true; | |
168 | } | |
169 | } | |
170 | } | |
171 | ||
172 | deadline = qemu_timeout_ns_to_ms(timerlistgroup_deadline_ns(&ctx->tlg)); | |
173 | if (deadline == 0) { | |
174 | *timeout = 0; | |
175 | return true; | |
176 | } else { | |
177 | *timeout = qemu_soonest_timeout(*timeout, deadline); | |
178 | } | |
179 | ||
180 | return false; | |
181 | } | |
182 | ||
183 | static gboolean | |
184 | aio_ctx_check(GSource *source) | |
185 | { | |
186 | AioContext *ctx = (AioContext *) source; | |
187 | QEMUBH *bh; | |
188 | ||
189 | for (bh = ctx->first_bh; bh; bh = bh->next) { | |
190 | if (!bh->deleted && bh->scheduled) { | |
191 | return true; | |
192 | } | |
193 | } | |
194 | return aio_pending(ctx) || (timerlistgroup_deadline_ns(&ctx->tlg) == 0); | |
195 | } | |
196 | ||
197 | static gboolean | |
198 | aio_ctx_dispatch(GSource *source, | |
199 | GSourceFunc callback, | |
200 | gpointer user_data) | |
201 | { | |
202 | AioContext *ctx = (AioContext *) source; | |
203 | ||
204 | assert(callback == NULL); | |
205 | aio_poll(ctx, false); | |
206 | return true; | |
207 | } | |
208 | ||
209 | static void | |
210 | aio_ctx_finalize(GSource *source) | |
211 | { | |
212 | AioContext *ctx = (AioContext *) source; | |
213 | ||
214 | thread_pool_free(ctx->thread_pool); | |
215 | aio_set_event_notifier(ctx, &ctx->notifier, NULL); | |
216 | event_notifier_cleanup(&ctx->notifier); | |
217 | qemu_mutex_destroy(&ctx->bh_lock); | |
218 | g_array_free(ctx->pollfds, TRUE); | |
219 | timerlistgroup_deinit(&ctx->tlg); | |
220 | } | |
221 | ||
222 | static GSourceFuncs aio_source_funcs = { | |
223 | aio_ctx_prepare, | |
224 | aio_ctx_check, | |
225 | aio_ctx_dispatch, | |
226 | aio_ctx_finalize | |
227 | }; | |
228 | ||
229 | GSource *aio_get_g_source(AioContext *ctx) | |
230 | { | |
231 | g_source_ref(&ctx->source); | |
232 | return &ctx->source; | |
233 | } | |
234 | ||
235 | ThreadPool *aio_get_thread_pool(AioContext *ctx) | |
236 | { | |
237 | if (!ctx->thread_pool) { | |
238 | ctx->thread_pool = thread_pool_new(ctx); | |
239 | } | |
240 | return ctx->thread_pool; | |
241 | } | |
242 | ||
243 | void aio_notify(AioContext *ctx) | |
244 | { | |
245 | event_notifier_set(&ctx->notifier); | |
246 | } | |
247 | ||
248 | static void aio_timerlist_notify(void *opaque) | |
249 | { | |
250 | aio_notify(opaque); | |
251 | } | |
252 | ||
253 | AioContext *aio_context_new(void) | |
254 | { | |
255 | AioContext *ctx; | |
256 | ctx = (AioContext *) g_source_new(&aio_source_funcs, sizeof(AioContext)); | |
257 | ctx->pollfds = g_array_new(FALSE, FALSE, sizeof(GPollFD)); | |
258 | ctx->thread_pool = NULL; | |
259 | qemu_mutex_init(&ctx->bh_lock); | |
260 | event_notifier_init(&ctx->notifier, false); | |
261 | aio_set_event_notifier(ctx, &ctx->notifier, | |
262 | (EventNotifierHandler *) | |
263 | event_notifier_test_and_clear); | |
264 | timerlistgroup_init(&ctx->tlg, aio_timerlist_notify, ctx); | |
265 | ||
266 | return ctx; | |
267 | } | |
268 | ||
269 | void aio_context_ref(AioContext *ctx) | |
270 | { | |
271 | g_source_ref(&ctx->source); | |
272 | } | |
273 | ||
274 | void aio_context_unref(AioContext *ctx) | |
275 | { | |
276 | g_source_unref(&ctx->source); | |
277 | } |