@samitouri / QOSamiQemu
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1 /*
2 * QEMU yank feature
3 *
4 * Copyright (c) Lukas Straub <lukasstraub2@web.de>
5 *
6 * This work is licensed under the terms of the GNU GPL, version 2 or later.
7 * See the COPYING file in the top-level directory.
8 */
9
10 #include "qemu/osdep.h"
11 #include "qapi/error.h"
12 #include "qemu/thread.h"
13 #include "qemu/queue.h"
14 #include "qemu/lockable.h"
15 #include "qapi/qapi-commands-yank.h"
16 #include "qapi/qapi-visit-yank.h"
17 #include "qapi/clone-visitor.h"
18 #include "qemu/yank.h"
19
20 struct YankFuncAndParam {
21 YankFn *func;
22 void *opaque;
23 QLIST_ENTRY(YankFuncAndParam) next;
24 };
25
26 struct YankInstanceEntry {
27 YankInstance *instance;
28 QLIST_HEAD(, YankFuncAndParam) yankfns;
29 QLIST_ENTRY(YankInstanceEntry) next;
30 };
31
32 typedef struct YankFuncAndParam YankFuncAndParam;
33 typedef struct YankInstanceEntry YankInstanceEntry;
34
35 /*
36 * This lock protects the yank_instance_list below. Because it's taken by
37 * OOB-capable commands, it must be "fast", i.e. it may only be held for a
38 * bounded, short time. See docs/devel/qapi-code-gen.rst for additional
39 * information.
40 */
41 static QemuMutex yank_lock;
42
43 static QLIST_HEAD(, YankInstanceEntry) yank_instance_list
44 = QLIST_HEAD_INITIALIZER(yank_instance_list);
45
46 static bool yank_instance_equal(const YankInstance *a, const YankInstance *b)
47 {
48 if (a->type != b->type) {
49 return false;
50 }
51
52 switch (a->type) {
53 case YANK_INSTANCE_TYPE_BLOCK_NODE:
54 return g_str_equal(a->u.block_node.node_name,
55 b->u.block_node.node_name);
56
57 case YANK_INSTANCE_TYPE_CHARDEV:
58 return g_str_equal(a->u.chardev.id, b->u.chardev.id);
59
60 case YANK_INSTANCE_TYPE_MIGRATION:
61 return true;
62
63 default:
64 abort();
65 }
66 }
67
68 static YankInstanceEntry *yank_find_entry(const YankInstance *instance)
69 {
70 YankInstanceEntry *entry;
71
72 QLIST_FOREACH(entry, &yank_instance_list, next) {
73 if (yank_instance_equal(entry->instance, instance)) {
74 return entry;
75 }
76 }
77 return NULL;
78 }
79
80 bool yank_register_instance(const YankInstance *instance, Error **errp)
81 {
82 YankInstanceEntry *entry;
83
84 QEMU_LOCK_GUARD(&yank_lock);
85
86 if (yank_find_entry(instance)) {
87 error_setg(errp, "duplicate yank instance");
88 return false;
89 }
90
91 entry = g_new0(YankInstanceEntry, 1);
92 entry->instance = QAPI_CLONE(YankInstance, instance);
93 QLIST_INIT(&entry->yankfns);
94 QLIST_INSERT_HEAD(&yank_instance_list, entry, next);
95
96 return true;
97 }
98
99 void yank_unregister_instance(const YankInstance *instance)
100 {
101 YankInstanceEntry *entry;
102
103 QEMU_LOCK_GUARD(&yank_lock);
104 entry = yank_find_entry(instance);
105 assert(entry);
106
107 assert(QLIST_EMPTY(&entry->yankfns));
108 QLIST_REMOVE(entry, next);
109 qapi_free_YankInstance(entry->instance);
110 g_free(entry);
111 }
112
113 void yank_register_function(const YankInstance *instance,
114 YankFn *func,
115 void *opaque)
116 {
117 YankInstanceEntry *entry;
118 YankFuncAndParam *func_entry;
119
120 QEMU_LOCK_GUARD(&yank_lock);
121 entry = yank_find_entry(instance);
122 assert(entry);
123
124 func_entry = g_new0(YankFuncAndParam, 1);
125 func_entry->func = func;
126 func_entry->opaque = opaque;
127
128 QLIST_INSERT_HEAD(&entry->yankfns, func_entry, next);
129 }
130
131 void yank_unregister_function(const YankInstance *instance,
132 YankFn *func,
133 void *opaque)
134 {
135 YankInstanceEntry *entry;
136 YankFuncAndParam *func_entry;
137
138 QEMU_LOCK_GUARD(&yank_lock);
139 entry = yank_find_entry(instance);
140 assert(entry);
141
142 QLIST_FOREACH(func_entry, &entry->yankfns, next) {
143 if (func_entry->func == func && func_entry->opaque == opaque) {
144 QLIST_REMOVE(func_entry, next);
145 g_free(func_entry);
146 return;
147 }
148 }
149
150 abort();
151 }
152
153 void qmp_yank(YankInstanceList *instances,
154 Error **errp)
155 {
156 YankInstanceList *tail;
157 YankInstanceEntry *entry;
158 YankFuncAndParam *func_entry;
159
160 QEMU_LOCK_GUARD(&yank_lock);
161 for (tail = instances; tail; tail = tail->next) {
162 entry = yank_find_entry(tail->value);
163 if (!entry) {
164 error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND, "Instance not found");
165 return;
166 }
167 }
168 for (tail = instances; tail; tail = tail->next) {
169 entry = yank_find_entry(tail->value);
170 assert(entry);
171 QLIST_FOREACH(func_entry, &entry->yankfns, next) {
172 func_entry->func(func_entry->opaque);
173 }
174 }
175 }
176
177 YankInstanceList *qmp_query_yank(Error **errp)
178 {
179 YankInstanceEntry *entry;
180 YankInstanceList *ret;
181
182 ret = NULL;
183
184 QEMU_LOCK_GUARD(&yank_lock);
185 QLIST_FOREACH(entry, &yank_instance_list, next) {
186 YankInstanceList *new_entry;
187 new_entry = g_new0(YankInstanceList, 1);
188 new_entry->value = QAPI_CLONE(YankInstance, entry->instance);
189 new_entry->next = ret;
190 ret = new_entry;
191 }
192
193 return ret;
194 }
195
196 static void __attribute__((__constructor__)) yank_init(void)
197 {
198 qemu_mutex_init(&yank_lock);
199 }