summaryrefslogtreecommitdiffstats
path: root/util/yank.c
blob: abf47c346d14a1225f93ae5b941db9abf05a9d22 (plain) (blame)
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
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
/*
 * QEMU yank feature
 *
 * Copyright (c) Lukas Straub <lukasstraub2@web.de>
 *
 * This work is licensed under the terms of the GNU GPL, version 2 or later.
 * See the COPYING file in the top-level directory.
 */

#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu/thread.h"
#include "qemu/queue.h"
#include "qemu/lockable.h"
#include "qapi/qapi-commands-yank.h"
#include "qapi/qapi-visit-yank.h"
#include "qapi/clone-visitor.h"
#include "qemu/yank.h"

struct YankFuncAndParam {
    YankFn *func;
    void *opaque;
    QLIST_ENTRY(YankFuncAndParam) next;
};

struct YankInstanceEntry {
    YankInstance *instance;
    QLIST_HEAD(, YankFuncAndParam) yankfns;
    QLIST_ENTRY(YankInstanceEntry) next;
};

typedef struct YankFuncAndParam YankFuncAndParam;
typedef struct YankInstanceEntry YankInstanceEntry;

/*
 * This lock protects the yank_instance_list below. Because it's taken by
 * OOB-capable commands, it must be "fast", i.e. it may only be held for a
 * bounded, short time. See docs/devel/qapi-code-gen.txt for additional
 * information.
 */
static QemuMutex yank_lock;

static QLIST_HEAD(, YankInstanceEntry) yank_instance_list
    = QLIST_HEAD_INITIALIZER(yank_instance_list);

static bool yank_instance_equal(const YankInstance *a, const YankInstance *b)
{
    if (a->type != b->type) {
        return false;
    }

    switch (a->type) {
    case YANK_INSTANCE_TYPE_BLOCK_NODE:
        return g_str_equal(a->u.block_node.node_name,
                           b->u.block_node.node_name);

    case YANK_INSTANCE_TYPE_CHARDEV:
        return g_str_equal(a->u.chardev.id, b->u.chardev.id);

    case YANK_INSTANCE_TYPE_MIGRATION:
        return true;

    default:
        abort();
    }
}

static YankInstanceEntry *yank_find_entry(const YankInstance *instance)
{
    YankInstanceEntry *entry;

    QLIST_FOREACH(entry, &yank_instance_list, next) {
        if (yank_instance_equal(entry->instance, instance)) {
            return entry;
        }
    }
    return NULL;
}

bool yank_register_instance(const YankInstance *instance, Error **errp)
{
    YankInstanceEntry *entry;

    QEMU_LOCK_GUARD(&yank_lock);

    if (yank_find_entry(instance)) {
        error_setg(errp, "duplicate yank instance");
        return false;
    }

    entry = g_new0(YankInstanceEntry, 1);
    entry->instance = QAPI_CLONE(YankInstance, instance);
    QLIST_INIT(&entry->yankfns);
    QLIST_INSERT_HEAD(&yank_instance_list, entry, next);

    return true;
}

void yank_unregister_instance(const YankInstance *instance)
{
    YankInstanceEntry *entry;

    QEMU_LOCK_GUARD(&yank_lock);
    entry = yank_find_entry(instance);
    assert(entry);

    assert(QLIST_EMPTY(&entry->yankfns));
    QLIST_REMOVE(entry, next);
    qapi_free_YankInstance(entry->instance);
    g_free(entry);
}

void yank_register_function(const YankInstance *instance,
                            YankFn *func,
                            void *opaque)
{
    YankInstanceEntry *entry;
    YankFuncAndParam *func_entry;

    QEMU_LOCK_GUARD(&yank_lock);
    entry = yank_find_entry(instance);
    assert(entry);

    func_entry = g_new0(YankFuncAndParam, 1);
    func_entry->func = func;
    func_entry->opaque = opaque;

    QLIST_INSERT_HEAD(&entry->yankfns, func_entry, next);
}

void yank_unregister_function(const YankInstance *instance,
                              YankFn *func,
                              void *opaque)
{
    YankInstanceEntry *entry;
    YankFuncAndParam *func_entry;

    QEMU_LOCK_GUARD(&yank_lock);
    entry = yank_find_entry(instance);
    assert(entry);

    QLIST_FOREACH(func_entry, &entry->yankfns, next) {
        if (func_entry->func == func && func_entry->opaque == opaque) {
            QLIST_REMOVE(func_entry, next);
            g_free(func_entry);
            return;
        }
    }

    abort();
}

void qmp_yank(YankInstanceList *instances,
              Error **errp)
{
    YankInstanceList *tail;
    YankInstanceEntry *entry;
    YankFuncAndParam *func_entry;

    QEMU_LOCK_GUARD(&yank_lock);
    for (tail = instances; tail; tail = tail->next) {
        entry = yank_find_entry(tail->value);
        if (!entry) {
            error_set(errp, ERROR_CLASS_DEVICE_NOT_FOUND, "Instance not found");
            return;
        }
    }
    for (tail = instances; tail; tail = tail->next) {
        entry = yank_find_entry(tail->value);
        assert(entry);
        QLIST_FOREACH(func_entry, &entry->yankfns, next) {
            func_entry->func(func_entry->opaque);
        }
    }
}

YankInstanceList *qmp_query_yank(Error **errp)
{
    YankInstanceEntry *entry;
    YankInstanceList *ret;

    ret = NULL;

    QEMU_LOCK_GUARD(&yank_lock);
    QLIST_FOREACH(entry, &yank_instance_list, next) {
        YankInstanceList *new_entry;
        new_entry = g_new0(YankInstanceList, 1);
        new_entry->value = QAPI_CLONE(YankInstance, entry->instance);
        new_entry->next = ret;
        ret = new_entry;
    }

    return ret;
}

static void __attribute__((__constructor__)) yank_init(void)
{
    qemu_mutex_init(&yank_lock);
}