acl: fix memory leak
[qemu.git] / coroutine-gthread.c
1 /*
2 * GThread coroutine initialization code
3 *
4 * Copyright (C) 2006 Anthony Liguori <anthony@codemonkey.ws>
5 * Copyright (C) 2011 Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
6 *
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.0 of the License, or (at your option) any later version.
11 *
12 * This library is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
19 */
20
21 #include <glib.h>
22 #include "qemu-common.h"
23 #include "block/coroutine_int.h"
24
25 typedef struct {
26 Coroutine base;
27 GThread *thread;
28 bool runnable;
29 bool free_on_thread_exit;
30 CoroutineAction action;
31 } CoroutineGThread;
32
33 static CompatGMutex coroutine_lock;
34 static CompatGCond coroutine_cond;
35
36 /* GLib 2.31 and beyond deprecated various parts of the thread API,
37 * but the new interfaces are not available in older GLib versions
38 * so we have to cope with both.
39 */
40 #if GLIB_CHECK_VERSION(2, 31, 0)
41 /* Awkwardly, the GPrivate API doesn't provide a way to update the
42 * GDestroyNotify handler for the coroutine key dynamically. So instead
43 * we track whether or not the CoroutineGThread should be freed on
44 * thread exit / coroutine key update using the free_on_thread_exit
45 * field.
46 */
47 static void coroutine_destroy_notify(gpointer data)
48 {
49 CoroutineGThread *co = data;
50 if (co && co->free_on_thread_exit) {
51 g_free(co);
52 }
53 }
54
55 static GPrivate coroutine_key = G_PRIVATE_INIT(coroutine_destroy_notify);
56
57 static inline CoroutineGThread *get_coroutine_key(void)
58 {
59 return g_private_get(&coroutine_key);
60 }
61
62 static inline void set_coroutine_key(CoroutineGThread *co,
63 bool free_on_thread_exit)
64 {
65 /* Unlike g_static_private_set() this does not call the GDestroyNotify
66 * if the previous value of the key was NULL. Fortunately we only need
67 * the GDestroyNotify in the non-NULL key case.
68 */
69 co->free_on_thread_exit = free_on_thread_exit;
70 g_private_replace(&coroutine_key, co);
71 }
72
73 static inline GThread *create_thread(GThreadFunc func, gpointer data)
74 {
75 return g_thread_new("coroutine", func, data);
76 }
77
78 #else
79
80 /* Handle older GLib versions */
81
82 static GStaticPrivate coroutine_key = G_STATIC_PRIVATE_INIT;
83
84 static inline CoroutineGThread *get_coroutine_key(void)
85 {
86 return g_static_private_get(&coroutine_key);
87 }
88
89 static inline void set_coroutine_key(CoroutineGThread *co,
90 bool free_on_thread_exit)
91 {
92 g_static_private_set(&coroutine_key, co,
93 free_on_thread_exit ? (GDestroyNotify)g_free : NULL);
94 }
95
96 static inline GThread *create_thread(GThreadFunc func, gpointer data)
97 {
98 return g_thread_create_full(func, data, 0, TRUE, TRUE,
99 G_THREAD_PRIORITY_NORMAL, NULL);
100 }
101
102 #endif
103
104
105 static void __attribute__((constructor)) coroutine_init(void)
106 {
107 #if !GLIB_CHECK_VERSION(2, 31, 0)
108 if (!g_thread_supported()) {
109 g_thread_init(NULL);
110 }
111 #endif
112 }
113
114 static void coroutine_wait_runnable_locked(CoroutineGThread *co)
115 {
116 while (!co->runnable) {
117 g_cond_wait(&coroutine_cond, &coroutine_lock);
118 }
119 }
120
121 static void coroutine_wait_runnable(CoroutineGThread *co)
122 {
123 g_mutex_lock(&coroutine_lock);
124 coroutine_wait_runnable_locked(co);
125 g_mutex_unlock(&coroutine_lock);
126 }
127
128 static gpointer coroutine_thread(gpointer opaque)
129 {
130 CoroutineGThread *co = opaque;
131
132 set_coroutine_key(co, false);
133 coroutine_wait_runnable(co);
134 co->base.entry(co->base.entry_arg);
135 qemu_coroutine_switch(&co->base, co->base.caller, COROUTINE_TERMINATE);
136 return NULL;
137 }
138
139 Coroutine *qemu_coroutine_new(void)
140 {
141 CoroutineGThread *co;
142
143 co = g_malloc0(sizeof(*co));
144 co->thread = create_thread(coroutine_thread, co);
145 if (!co->thread) {
146 g_free(co);
147 return NULL;
148 }
149 return &co->base;
150 }
151
152 void qemu_coroutine_delete(Coroutine *co_)
153 {
154 CoroutineGThread *co = DO_UPCAST(CoroutineGThread, base, co_);
155
156 g_thread_join(co->thread);
157 g_free(co);
158 }
159
160 CoroutineAction qemu_coroutine_switch(Coroutine *from_,
161 Coroutine *to_,
162 CoroutineAction action)
163 {
164 CoroutineGThread *from = DO_UPCAST(CoroutineGThread, base, from_);
165 CoroutineGThread *to = DO_UPCAST(CoroutineGThread, base, to_);
166
167 g_mutex_lock(&coroutine_lock);
168 from->runnable = false;
169 from->action = action;
170 to->runnable = true;
171 to->action = action;
172 g_cond_broadcast(&coroutine_cond);
173
174 if (action != COROUTINE_TERMINATE) {
175 coroutine_wait_runnable_locked(from);
176 }
177 g_mutex_unlock(&coroutine_lock);
178 return from->action;
179 }
180
181 Coroutine *qemu_coroutine_self(void)
182 {
183 CoroutineGThread *co = get_coroutine_key();
184 if (!co) {
185 co = g_malloc0(sizeof(*co));
186 co->runnable = true;
187 set_coroutine_key(co, true);
188 }
189
190 return &co->base;
191 }
192
193 bool qemu_in_coroutine(void)
194 {
195 CoroutineGThread *co = get_coroutine_key();
196
197 return co && co->base.caller;
198 }