Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging
[qemu.git] / aio-posix.c
1 /*
2 * QEMU aio implementation
3 *
4 * Copyright IBM, Corp. 2008
5 *
6 * Authors:
7 * Anthony Liguori <aliguori@us.ibm.com>
8 *
9 * This work is licensed under the terms of the GNU GPL, version 2. See
10 * the COPYING file in the top-level directory.
11 *
12 * Contributions after 2012-01-13 are licensed under the terms of the
13 * GNU GPL, version 2 or (at your option) any later version.
14 */
15
16 #include "qemu-common.h"
17 #include "block/block.h"
18 #include "qemu/queue.h"
19 #include "qemu/sockets.h"
20
21 struct AioHandler
22 {
23 GPollFD pfd;
24 IOHandler *io_read;
25 IOHandler *io_write;
26 int deleted;
27 int pollfds_idx;
28 void *opaque;
29 QLIST_ENTRY(AioHandler) node;
30 };
31
32 static AioHandler *find_aio_handler(AioContext *ctx, int fd)
33 {
34 AioHandler *node;
35
36 QLIST_FOREACH(node, &ctx->aio_handlers, node) {
37 if (node->pfd.fd == fd)
38 if (!node->deleted)
39 return node;
40 }
41
42 return NULL;
43 }
44
45 void aio_set_fd_handler(AioContext *ctx,
46 int fd,
47 IOHandler *io_read,
48 IOHandler *io_write,
49 void *opaque)
50 {
51 AioHandler *node;
52
53 node = find_aio_handler(ctx, fd);
54
55 /* Are we deleting the fd handler? */
56 if (!io_read && !io_write) {
57 if (node) {
58 g_source_remove_poll(&ctx->source, &node->pfd);
59
60 /* If the lock is held, just mark the node as deleted */
61 if (ctx->walking_handlers) {
62 node->deleted = 1;
63 node->pfd.revents = 0;
64 } else {
65 /* Otherwise, delete it for real. We can't just mark it as
66 * deleted because deleted nodes are only cleaned up after
67 * releasing the walking_handlers lock.
68 */
69 QLIST_REMOVE(node, node);
70 g_free(node);
71 }
72 }
73 } else {
74 if (node == NULL) {
75 /* Alloc and insert if it's not already there */
76 node = g_malloc0(sizeof(AioHandler));
77 node->pfd.fd = fd;
78 QLIST_INSERT_HEAD(&ctx->aio_handlers, node, node);
79
80 g_source_add_poll(&ctx->source, &node->pfd);
81 }
82 /* Update handler with latest information */
83 node->io_read = io_read;
84 node->io_write = io_write;
85 node->opaque = opaque;
86 node->pollfds_idx = -1;
87
88 node->pfd.events = (io_read ? G_IO_IN | G_IO_HUP | G_IO_ERR : 0);
89 node->pfd.events |= (io_write ? G_IO_OUT | G_IO_ERR : 0);
90 }
91
92 aio_notify(ctx);
93 }
94
95 void aio_set_event_notifier(AioContext *ctx,
96 EventNotifier *notifier,
97 EventNotifierHandler *io_read)
98 {
99 aio_set_fd_handler(ctx, event_notifier_get_fd(notifier),
100 (IOHandler *)io_read, NULL, notifier);
101 }
102
103 bool aio_pending(AioContext *ctx)
104 {
105 AioHandler *node;
106
107 QLIST_FOREACH(node, &ctx->aio_handlers, node) {
108 int revents;
109
110 revents = node->pfd.revents & node->pfd.events;
111 if (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR) && node->io_read) {
112 return true;
113 }
114 if (revents & (G_IO_OUT | G_IO_ERR) && node->io_write) {
115 return true;
116 }
117 }
118
119 return false;
120 }
121
122 static bool aio_dispatch(AioContext *ctx)
123 {
124 AioHandler *node;
125 bool progress = false;
126
127 /*
128 * We have to walk very carefully in case qemu_aio_set_fd_handler is
129 * called while we're walking.
130 */
131 node = QLIST_FIRST(&ctx->aio_handlers);
132 while (node) {
133 AioHandler *tmp;
134 int revents;
135
136 ctx->walking_handlers++;
137
138 revents = node->pfd.revents & node->pfd.events;
139 node->pfd.revents = 0;
140
141 if (!node->deleted &&
142 (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR)) &&
143 node->io_read) {
144 node->io_read(node->opaque);
145
146 /* aio_notify() does not count as progress */
147 if (node->opaque != &ctx->notifier) {
148 progress = true;
149 }
150 }
151 if (!node->deleted &&
152 (revents & (G_IO_OUT | G_IO_ERR)) &&
153 node->io_write) {
154 node->io_write(node->opaque);
155 progress = true;
156 }
157
158 tmp = node;
159 node = QLIST_NEXT(node, node);
160
161 ctx->walking_handlers--;
162
163 if (!ctx->walking_handlers && tmp->deleted) {
164 QLIST_REMOVE(tmp, node);
165 g_free(tmp);
166 }
167 }
168
169 /* Run our timers */
170 progress |= timerlistgroup_run_timers(&ctx->tlg);
171
172 return progress;
173 }
174
175 bool aio_poll(AioContext *ctx, bool blocking)
176 {
177 AioHandler *node;
178 int ret;
179 bool progress;
180
181 progress = false;
182
183 /*
184 * If there are callbacks left that have been queued, we need to call them.
185 * Do not call select in this case, because it is possible that the caller
186 * does not need a complete flush (as is the case for qemu_aio_wait loops).
187 */
188 if (aio_bh_poll(ctx)) {
189 blocking = false;
190 progress = true;
191 }
192
193 if (aio_dispatch(ctx)) {
194 progress = true;
195 }
196
197 if (progress && !blocking) {
198 return true;
199 }
200
201 ctx->walking_handlers++;
202
203 g_array_set_size(ctx->pollfds, 0);
204
205 /* fill pollfds */
206 QLIST_FOREACH(node, &ctx->aio_handlers, node) {
207 node->pollfds_idx = -1;
208 if (!node->deleted && node->pfd.events) {
209 GPollFD pfd = {
210 .fd = node->pfd.fd,
211 .events = node->pfd.events,
212 };
213 node->pollfds_idx = ctx->pollfds->len;
214 g_array_append_val(ctx->pollfds, pfd);
215 }
216 }
217
218 ctx->walking_handlers--;
219
220 /* wait until next event */
221 ret = qemu_poll_ns((GPollFD *)ctx->pollfds->data,
222 ctx->pollfds->len,
223 blocking ? timerlistgroup_deadline_ns(&ctx->tlg) : 0);
224
225 /* if we have any readable fds, dispatch event */
226 if (ret > 0) {
227 QLIST_FOREACH(node, &ctx->aio_handlers, node) {
228 if (node->pollfds_idx != -1) {
229 GPollFD *pfd = &g_array_index(ctx->pollfds, GPollFD,
230 node->pollfds_idx);
231 node->pfd.revents = pfd->revents;
232 }
233 }
234 }
235
236 /* Run dispatch even if there were no readable fds to run timers */
237 if (aio_dispatch(ctx)) {
238 progress = true;
239 }
240
241 return progress;
242 }