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Commit | Line | Data |
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2292b339 MT |
1 | /* |
2 | * event notifier support | |
3 | * | |
4 | * Copyright Red Hat, Inc. 2010 | |
5 | * | |
6 | * Authors: | |
7 | * Michael S. Tsirkin <mst@redhat.com> | |
8 | * | |
6b620ca3 PB |
9 | * This work is licensed under the terms of the GNU GPL, version 2 or later. |
10 | * See the COPYING file in the top-level directory. | |
2292b339 MT |
11 | */ |
12 | ||
aafd7584 | 13 | #include "qemu/osdep.h" |
f348b6d1 | 14 | #include "qemu/cutils.h" |
1de7afc9 | 15 | #include "qemu/event_notifier.h" |
1de7afc9 | 16 | #include "qemu/main-loop.h" |
e80c262b | 17 | |
2292b339 MT |
18 | #ifdef CONFIG_EVENTFD |
19 | #include <sys/eventfd.h> | |
20 | #endif | |
21 | ||
330b5836 MA |
22 | #ifdef CONFIG_EVENTFD |
23 | /* | |
24 | * Initialize @e with existing file descriptor @fd. | |
25 | * @fd must be a genuine eventfd object, emulation with pipe won't do. | |
26 | */ | |
e80c262b PB |
27 | void event_notifier_init_fd(EventNotifier *e, int fd) |
28 | { | |
d0cc2fbf PB |
29 | e->rfd = fd; |
30 | e->wfd = fd; | |
e34e47eb | 31 | e->initialized = true; |
e80c262b | 32 | } |
330b5836 | 33 | #endif |
e80c262b | 34 | |
2292b339 MT |
35 | int event_notifier_init(EventNotifier *e, int active) |
36 | { | |
d0cc2fbf PB |
37 | int fds[2]; |
38 | int ret; | |
39 | ||
2292b339 | 40 | #ifdef CONFIG_EVENTFD |
d0cc2fbf | 41 | ret = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC); |
2292b339 | 42 | #else |
d0cc2fbf PB |
43 | ret = -1; |
44 | errno = ENOSYS; | |
2292b339 | 45 | #endif |
d0cc2fbf PB |
46 | if (ret >= 0) { |
47 | e->rfd = e->wfd = ret; | |
48 | } else { | |
49 | if (errno != ENOSYS) { | |
50 | return -errno; | |
51 | } | |
a7241974 | 52 | if (!g_unix_open_pipe(fds, FD_CLOEXEC, NULL)) { |
d0cc2fbf PB |
53 | return -errno; |
54 | } | |
4d14cb0c | 55 | if (!g_unix_set_fd_nonblocking(fds[0], true, NULL)) { |
d0cc2fbf PB |
56 | ret = -errno; |
57 | goto fail; | |
58 | } | |
4d14cb0c | 59 | if (!g_unix_set_fd_nonblocking(fds[1], true, NULL)) { |
d0cc2fbf PB |
60 | ret = -errno; |
61 | goto fail; | |
62 | } | |
63 | e->rfd = fds[0]; | |
64 | e->wfd = fds[1]; | |
65 | } | |
82e27568 | 66 | e->initialized = true; |
d0cc2fbf PB |
67 | if (active) { |
68 | event_notifier_set(e); | |
69 | } | |
70 | return 0; | |
71 | ||
72 | fail: | |
73 | close(fds[0]); | |
74 | close(fds[1]); | |
75 | return ret; | |
2292b339 MT |
76 | } |
77 | ||
78 | void event_notifier_cleanup(EventNotifier *e) | |
79 | { | |
e34e47eb ML |
80 | if (!e->initialized) { |
81 | return; | |
82 | } | |
83 | ||
d0cc2fbf PB |
84 | if (e->rfd != e->wfd) { |
85 | close(e->rfd); | |
86 | } | |
e34e47eb | 87 | |
105e1023 | 88 | e->rfd = -1; |
d0cc2fbf | 89 | close(e->wfd); |
aa262928 | 90 | e->wfd = -1; |
e34e47eb | 91 | e->initialized = false; |
2292b339 MT |
92 | } |
93 | ||
12f0b68c | 94 | int event_notifier_get_fd(const EventNotifier *e) |
2292b339 | 95 | { |
d0cc2fbf | 96 | return e->rfd; |
2292b339 MT |
97 | } |
98 | ||
3bcf0fb3 SL |
99 | int event_notifier_get_wfd(const EventNotifier *e) |
100 | { | |
101 | return e->wfd; | |
102 | } | |
103 | ||
2ec10b95 PB |
104 | int event_notifier_set(EventNotifier *e) |
105 | { | |
d0cc2fbf PB |
106 | static const uint64_t value = 1; |
107 | ssize_t ret; | |
108 | ||
e34e47eb ML |
109 | if (!e->initialized) { |
110 | return -1; | |
111 | } | |
112 | ||
d0cc2fbf PB |
113 | do { |
114 | ret = write(e->wfd, &value, sizeof(value)); | |
115 | } while (ret < 0 && errno == EINTR); | |
116 | ||
117 | /* EAGAIN is fine, a read must be pending. */ | |
118 | if (ret < 0 && errno != EAGAIN) { | |
119 | return -errno; | |
120 | } | |
121 | return 0; | |
2ec10b95 PB |
122 | } |
123 | ||
2292b339 MT |
124 | int event_notifier_test_and_clear(EventNotifier *e) |
125 | { | |
d0cc2fbf PB |
126 | int value; |
127 | ssize_t len; | |
128 | char buffer[512]; | |
129 | ||
e34e47eb ML |
130 | if (!e->initialized) { |
131 | return 0; | |
132 | } | |
133 | ||
d0cc2fbf PB |
134 | /* Drain the notify pipe. For eventfd, only 8 bytes will be read. */ |
135 | value = 0; | |
136 | do { | |
137 | len = read(e->rfd, buffer, sizeof(buffer)); | |
138 | value |= (len > 0); | |
139 | } while ((len == -1 && errno == EINTR) || len == sizeof(buffer)); | |
140 | ||
141 | return value; | |
2292b339 | 142 | } |