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Commit | Line | Data |
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7719f3c9 SH |
1 | /* |
2 | * AioContext wait support | |
3 | * | |
4 | * Copyright (C) 2018 Red Hat, Inc. | |
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/osdep.h" | |
26 | #include "qemu/main-loop.h" | |
27 | #include "block/aio-wait.h" | |
28 | ||
cfe29d82 KW |
29 | AioWait global_aio_wait; |
30 | ||
7719f3c9 SH |
31 | static void dummy_bh_cb(void *opaque) |
32 | { | |
33 | /* The point is to make AIO_WAIT_WHILE()'s aio_poll() return */ | |
34 | } | |
35 | ||
cfe29d82 | 36 | void aio_wait_kick(void) |
7719f3c9 | 37 | { |
7455ff1a EGE |
38 | /* |
39 | * Paired with smp_mb in AIO_WAIT_WHILE. Here we have: | |
40 | * write(condition); | |
41 | * aio_wait_kick() { | |
42 | * smp_mb(); | |
43 | * read(num_waiters); | |
44 | * } | |
45 | * | |
46 | * And in AIO_WAIT_WHILE: | |
47 | * write(num_waiters); | |
48 | * smp_mb(); | |
49 | * read(condition); | |
50 | */ | |
51 | smp_mb(); | |
52 | ||
d73415a3 | 53 | if (qatomic_read(&global_aio_wait.num_waiters)) { |
7719f3c9 SH |
54 | aio_bh_schedule_oneshot(qemu_get_aio_context(), dummy_bh_cb, NULL); |
55 | } | |
56 | } | |
b89d92f3 SH |
57 | |
58 | typedef struct { | |
b89d92f3 SH |
59 | bool done; |
60 | QEMUBHFunc *cb; | |
61 | void *opaque; | |
62 | } AioWaitBHData; | |
63 | ||
64 | /* Context: BH in IOThread */ | |
65 | static void aio_wait_bh(void *opaque) | |
66 | { | |
67 | AioWaitBHData *data = opaque; | |
68 | ||
69 | data->cb(data->opaque); | |
70 | ||
71 | data->done = true; | |
cfe29d82 | 72 | aio_wait_kick(); |
b89d92f3 SH |
73 | } |
74 | ||
75 | void aio_wait_bh_oneshot(AioContext *ctx, QEMUBHFunc *cb, void *opaque) | |
76 | { | |
77 | AioWaitBHData data = { | |
78 | .cb = cb, | |
79 | .opaque = opaque, | |
80 | }; | |
81 | ||
82 | assert(qemu_get_current_aio_context() == qemu_get_aio_context()); | |
83 | ||
84 | aio_bh_schedule_oneshot(ctx, aio_wait_bh, &data); | |
3edf660a | 85 | AIO_WAIT_WHILE_UNLOCKED(NULL, !data.done); |
b89d92f3 | 86 | } |