1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
|
/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* epoll(7) file descriptor monitoring
*/
#include "qemu/osdep.h"
#include <sys/epoll.h>
#include "qemu/rcu_queue.h"
#include "aio-posix.h"
/* The fd number threshold to switch to epoll */
#define EPOLL_ENABLE_THRESHOLD 64
void fdmon_epoll_disable(AioContext *ctx)
{
if (ctx->epollfd >= 0) {
close(ctx->epollfd);
ctx->epollfd = -1;
}
/* Switch back */
ctx->fdmon_ops = &fdmon_poll_ops;
}
static inline int epoll_events_from_pfd(int pfd_events)
{
return (pfd_events & G_IO_IN ? EPOLLIN : 0) |
(pfd_events & G_IO_OUT ? EPOLLOUT : 0) |
(pfd_events & G_IO_HUP ? EPOLLHUP : 0) |
(pfd_events & G_IO_ERR ? EPOLLERR : 0);
}
static void fdmon_epoll_update(AioContext *ctx,
AioHandler *old_node,
AioHandler *new_node)
{
struct epoll_event event = {
.data.ptr = new_node,
.events = new_node ? epoll_events_from_pfd(new_node->pfd.events) : 0,
};
int r;
if (!new_node) {
r = epoll_ctl(ctx->epollfd, EPOLL_CTL_DEL, old_node->pfd.fd, &event);
} else if (!old_node) {
r = epoll_ctl(ctx->epollfd, EPOLL_CTL_ADD, new_node->pfd.fd, &event);
} else {
r = epoll_ctl(ctx->epollfd, EPOLL_CTL_MOD, new_node->pfd.fd, &event);
}
if (r) {
fdmon_epoll_disable(ctx);
}
}
static int fdmon_epoll_wait(AioContext *ctx, AioHandlerList *ready_list,
int64_t timeout)
{
GPollFD pfd = {
.fd = ctx->epollfd,
.events = G_IO_IN | G_IO_OUT | G_IO_HUP | G_IO_ERR,
};
AioHandler *node;
int i, ret = 0;
struct epoll_event events[128];
/* Fall back while external clients are disabled */
if (atomic_read(&ctx->external_disable_cnt)) {
return fdmon_poll_ops.wait(ctx, ready_list, timeout);
}
if (timeout > 0) {
ret = qemu_poll_ns(&pfd, 1, timeout);
if (ret > 0) {
timeout = 0;
}
}
if (timeout <= 0 || ret > 0) {
ret = epoll_wait(ctx->epollfd, events,
ARRAY_SIZE(events),
timeout);
if (ret <= 0) {
goto out;
}
for (i = 0; i < ret; i++) {
int ev = events[i].events;
int revents = (ev & EPOLLIN ? G_IO_IN : 0) |
(ev & EPOLLOUT ? G_IO_OUT : 0) |
(ev & EPOLLHUP ? G_IO_HUP : 0) |
(ev & EPOLLERR ? G_IO_ERR : 0);
node = events[i].data.ptr;
aio_add_ready_handler(ready_list, node, revents);
}
}
out:
return ret;
}
static const FDMonOps fdmon_epoll_ops = {
.update = fdmon_epoll_update,
.wait = fdmon_epoll_wait,
.need_wait = aio_poll_disabled,
};
static bool fdmon_epoll_try_enable(AioContext *ctx)
{
AioHandler *node;
struct epoll_event event;
QLIST_FOREACH_RCU(node, &ctx->aio_handlers, node) {
int r;
if (QLIST_IS_INSERTED(node, node_deleted) || !node->pfd.events) {
continue;
}
event.events = epoll_events_from_pfd(node->pfd.events);
event.data.ptr = node;
r = epoll_ctl(ctx->epollfd, EPOLL_CTL_ADD, node->pfd.fd, &event);
if (r) {
return false;
}
}
ctx->fdmon_ops = &fdmon_epoll_ops;
return true;
}
bool fdmon_epoll_try_upgrade(AioContext *ctx, unsigned npfd)
{
if (ctx->epollfd < 0) {
return false;
}
/* Do not upgrade while external clients are disabled */
if (atomic_read(&ctx->external_disable_cnt)) {
return false;
}
if (npfd >= EPOLL_ENABLE_THRESHOLD) {
if (fdmon_epoll_try_enable(ctx)) {
return true;
} else {
fdmon_epoll_disable(ctx);
}
}
return false;
}
void fdmon_epoll_setup(AioContext *ctx)
{
ctx->epollfd = epoll_create1(EPOLL_CLOEXEC);
if (ctx->epollfd == -1) {
fprintf(stderr, "Failed to create epoll instance: %s", strerror(errno));
}
}
|
