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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 "qemu-aio.h" | |
27 | #include "main-loop.h" | |
28 | ||
29 | /***********************************************************/ | |
30 | /* bottom halves (can be seen as timers which expire ASAP) */ | |
31 | ||
32 | struct QEMUBH { | |
33 | QEMUBHFunc *cb; | |
34 | void *opaque; | |
35 | QEMUBH *next; | |
36 | bool scheduled; | |
37 | bool idle; | |
38 | bool deleted; | |
39 | }; | |
40 | ||
41 | QEMUBH *aio_bh_new(AioContext *ctx, QEMUBHFunc *cb, void *opaque) | |
42 | { | |
43 | QEMUBH *bh; | |
44 | bh = g_malloc0(sizeof(QEMUBH)); | |
45 | bh->cb = cb; | |
46 | bh->opaque = opaque; | |
47 | bh->next = ctx->first_bh; | |
48 | ctx->first_bh = bh; | |
49 | return bh; | |
50 | } | |
51 | ||
52 | int aio_bh_poll(AioContext *ctx) | |
53 | { | |
54 | QEMUBH *bh, **bhp, *next; | |
55 | int ret; | |
56 | ||
57 | ctx->walking_bh++; | |
58 | ||
59 | ret = 0; | |
60 | for (bh = ctx->first_bh; bh; bh = next) { | |
61 | next = bh->next; | |
62 | if (!bh->deleted && bh->scheduled) { | |
63 | bh->scheduled = 0; | |
64 | if (!bh->idle) | |
65 | ret = 1; | |
66 | bh->idle = 0; | |
67 | bh->cb(bh->opaque); | |
68 | } | |
69 | } | |
70 | ||
71 | ctx->walking_bh--; | |
72 | ||
73 | /* remove deleted bhs */ | |
74 | if (!ctx->walking_bh) { | |
75 | bhp = &ctx->first_bh; | |
76 | while (*bhp) { | |
77 | bh = *bhp; | |
78 | if (bh->deleted) { | |
79 | *bhp = bh->next; | |
80 | g_free(bh); | |
81 | } else { | |
82 | bhp = &bh->next; | |
83 | } | |
84 | } | |
85 | } | |
86 | ||
87 | return ret; | |
88 | } | |
89 | ||
90 | void qemu_bh_schedule_idle(QEMUBH *bh) | |
91 | { | |
92 | if (bh->scheduled) | |
93 | return; | |
94 | bh->scheduled = 1; | |
95 | bh->idle = 1; | |
96 | } | |
97 | ||
98 | void qemu_bh_schedule(QEMUBH *bh) | |
99 | { | |
100 | if (bh->scheduled) | |
101 | return; | |
102 | bh->scheduled = 1; | |
103 | bh->idle = 0; | |
104 | /* stop the currently executing CPU to execute the BH ASAP */ | |
105 | qemu_notify_event(); | |
106 | } | |
107 | ||
108 | void qemu_bh_cancel(QEMUBH *bh) | |
109 | { | |
110 | bh->scheduled = 0; | |
111 | } | |
112 | ||
113 | void qemu_bh_delete(QEMUBH *bh) | |
114 | { | |
115 | bh->scheduled = 0; | |
116 | bh->deleted = 1; | |
117 | } | |
118 | ||
119 | void aio_bh_update_timeout(AioContext *ctx, uint32_t *timeout) | |
120 | { | |
121 | QEMUBH *bh; | |
122 | ||
123 | for (bh = ctx->first_bh; bh; bh = bh->next) { | |
124 | if (!bh->deleted && bh->scheduled) { | |
125 | if (bh->idle) { | |
126 | /* idle bottom halves will be polled at least | |
127 | * every 10ms */ | |
128 | *timeout = MIN(10, *timeout); | |
129 | } else { | |
130 | /* non-idle bottom halves will be executed | |
131 | * immediately */ | |
132 | *timeout = 0; | |
133 | break; | |
134 | } | |
135 | } | |
136 | } | |
137 | } | |
138 | ||
139 | static gboolean | |
140 | aio_ctx_prepare(GSource *source, gint *timeout) | |
141 | { | |
142 | AioContext *ctx = (AioContext *) source; | |
143 | uint32_t wait = -1; | |
144 | aio_bh_update_timeout(ctx, &wait); | |
145 | ||
146 | if (wait != -1) { | |
147 | *timeout = MIN(*timeout, wait); | |
148 | return wait == 0; | |
149 | } | |
150 | ||
151 | return false; | |
152 | } | |
153 | ||
154 | static gboolean | |
155 | aio_ctx_check(GSource *source) | |
156 | { | |
157 | AioContext *ctx = (AioContext *) source; | |
158 | QEMUBH *bh; | |
159 | ||
160 | for (bh = ctx->first_bh; bh; bh = bh->next) { | |
161 | if (!bh->deleted && bh->scheduled) { | |
162 | return true; | |
163 | } | |
164 | } | |
165 | return aio_pending(ctx); | |
166 | } | |
167 | ||
168 | static gboolean | |
169 | aio_ctx_dispatch(GSource *source, | |
170 | GSourceFunc callback, | |
171 | gpointer user_data) | |
172 | { | |
173 | AioContext *ctx = (AioContext *) source; | |
174 | ||
175 | assert(callback == NULL); | |
176 | aio_poll(ctx, false); | |
177 | return true; | |
178 | } | |
179 | ||
180 | static GSourceFuncs aio_source_funcs = { | |
181 | aio_ctx_prepare, | |
182 | aio_ctx_check, | |
183 | aio_ctx_dispatch, | |
184 | NULL | |
185 | }; | |
186 | ||
187 | GSource *aio_get_g_source(AioContext *ctx) | |
188 | { | |
189 | g_source_ref(&ctx->source); | |
190 | return &ctx->source; | |
191 | } | |
192 | ||
193 | AioContext *aio_context_new(void) | |
194 | { | |
195 | return (AioContext *) g_source_new(&aio_source_funcs, sizeof(AioContext)); | |
196 | } | |
197 | ||
198 | void aio_context_ref(AioContext *ctx) | |
199 | { | |
200 | g_source_ref(&ctx->source); | |
201 | } | |
202 | ||
203 | void aio_context_unref(AioContext *ctx) | |
204 | { | |
205 | g_source_unref(&ctx->source); | |
206 | } | |
207 | ||
208 | void aio_flush(AioContext *ctx) | |
209 | { | |
210 | while (aio_poll(ctx, true)); | |
211 | } |