ahci: Fix FIS decomposition
[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_prepare(AioContext *ctx)
104 {
105 return false;
106 }
107
108 bool aio_pending(AioContext *ctx)
109 {
110 AioHandler *node;
111
112 QLIST_FOREACH(node, &ctx->aio_handlers, node) {
113 int revents;
114
115 revents = node->pfd.revents & node->pfd.events;
116 if (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR) && node->io_read) {
117 return true;
118 }
119 if (revents & (G_IO_OUT | G_IO_ERR) && node->io_write) {
120 return true;
121 }
122 }
123
124 return false;
125 }
126
127 bool aio_dispatch(AioContext *ctx)
128 {
129 AioHandler *node;
130 bool progress = false;
131
132 /*
133 * If there are callbacks left that have been queued, we need to call them.
134 * Do not call select in this case, because it is possible that the caller
135 * does not need a complete flush (as is the case for aio_poll loops).
136 */
137 if (aio_bh_poll(ctx)) {
138 progress = true;
139 }
140
141 /*
142 * We have to walk very carefully in case aio_set_fd_handler is
143 * called while we're walking.
144 */
145 node = QLIST_FIRST(&ctx->aio_handlers);
146 while (node) {
147 AioHandler *tmp;
148 int revents;
149
150 ctx->walking_handlers++;
151
152 revents = node->pfd.revents & node->pfd.events;
153 node->pfd.revents = 0;
154
155 if (!node->deleted &&
156 (revents & (G_IO_IN | G_IO_HUP | G_IO_ERR)) &&
157 node->io_read) {
158 node->io_read(node->opaque);
159
160 /* aio_notify() does not count as progress */
161 if (node->opaque != &ctx->notifier) {
162 progress = true;
163 }
164 }
165 if (!node->deleted &&
166 (revents & (G_IO_OUT | G_IO_ERR)) &&
167 node->io_write) {
168 node->io_write(node->opaque);
169 progress = true;
170 }
171
172 tmp = node;
173 node = QLIST_NEXT(node, node);
174
175 ctx->walking_handlers--;
176
177 if (!ctx->walking_handlers && tmp->deleted) {
178 QLIST_REMOVE(tmp, node);
179 g_free(tmp);
180 }
181 }
182
183 /* Run our timers */
184 progress |= timerlistgroup_run_timers(&ctx->tlg);
185
186 return progress;
187 }
188
189 bool aio_poll(AioContext *ctx, bool blocking)
190 {
191 AioHandler *node;
192 bool was_dispatching;
193 int ret;
194 bool progress;
195
196 was_dispatching = ctx->dispatching;
197 progress = false;
198
199 /* aio_notify can avoid the expensive event_notifier_set if
200 * everything (file descriptors, bottom halves, timers) will
201 * be re-evaluated before the next blocking poll(). This is
202 * already true when aio_poll is called with blocking == false;
203 * if blocking == true, it is only true after poll() returns.
204 *
205 * If we're in a nested event loop, ctx->dispatching might be true.
206 * In that case we can restore it just before returning, but we
207 * have to clear it now.
208 */
209 aio_set_dispatching(ctx, !blocking);
210
211 ctx->walking_handlers++;
212
213 g_array_set_size(ctx->pollfds, 0);
214
215 /* fill pollfds */
216 QLIST_FOREACH(node, &ctx->aio_handlers, node) {
217 node->pollfds_idx = -1;
218 if (!node->deleted && node->pfd.events) {
219 GPollFD pfd = {
220 .fd = node->pfd.fd,
221 .events = node->pfd.events,
222 };
223 node->pollfds_idx = ctx->pollfds->len;
224 g_array_append_val(ctx->pollfds, pfd);
225 }
226 }
227
228 ctx->walking_handlers--;
229
230 /* wait until next event */
231 ret = qemu_poll_ns((GPollFD *)ctx->pollfds->data,
232 ctx->pollfds->len,
233 blocking ? aio_compute_timeout(ctx) : 0);
234
235 /* if we have any readable fds, dispatch event */
236 if (ret > 0) {
237 QLIST_FOREACH(node, &ctx->aio_handlers, node) {
238 if (node->pollfds_idx != -1) {
239 GPollFD *pfd = &g_array_index(ctx->pollfds, GPollFD,
240 node->pollfds_idx);
241 node->pfd.revents = pfd->revents;
242 }
243 }
244 }
245
246 /* Run dispatch even if there were no readable fds to run timers */
247 aio_set_dispatching(ctx, true);
248 if (aio_dispatch(ctx)) {
249 progress = true;
250 }
251
252 aio_set_dispatching(ctx, was_dispatching);
253 return progress;
254 }