配置libvirt coredumo后（https://www.cnblogs.com/maojun1998/p/17215214.html）
让测试一直迁移vm,一段时间后出现coredump
root 错误码: coredump.sh 严重错误,进程 coredump,dumpfile:/run/fs_mount//hdd/core.26956
1
2 qemu关于这块代码非常绕最后core在object_get_class
3
4 Chardev *s = be->chr;
5 src = CHARDEV_GET_CLASS(s)->chr_add_watch(s, cond);
6
7
8 #define CHARDEV_GET_CLASS(obj) \
9 OBJECT_GET_CLASS(ChardevClass, (obj), TYPE_CHARDEV)
10
11 #define OBJECT_GET_CLASS(class, obj, name) \
12 OBJECT_CLASS_CHECK(class, object_get_class(OBJECT(obj)), name)
13
14 #define OBJECT(obj) \
15 ((Object *)(obj))
16 #define OBJECT_CLASS_CHECK(class_type, class, name) \
17 ((class_type *)object_class_dynamic_cast_assert(OBJECT_CLASS(class), (name), \
18 __FILE__, __LINE__, __func__))
19 #define OBJECT_CLASS(class) \
20 ((ObjectClass *)(class))
21
22 ObjectClass *object_get_class(Object *obj)
23 {
24 return obj->class;
25 }
26 struct Chardev {
27 Object parent_obj;
28
29 QemuMutex chr_write_lock;
30 CharBackend *be;
31 char *label;
32 char *filename;
33 int logfd;
34 int be_open;
35 GSource *gsource;
36 GMainContext *gcontext;
37 DECLARE_BITMAP(features, QEMU_CHAR_FEATURE_LAST);
38 };
39 struct Object
40 {
41 /*< private >*/
42 ObjectClass *class;
43 ObjectFree *free;
44 GHashTable *properties;
45 uint32_t ref;
46 Object *parent;
47 };
48 struct ObjectClass
49 {
50 /*< private >*/
51 Type type;
52 GSList *interfaces;
53
54 const char *object_cast_cache[OBJECT_CLASS_CAST_CACHE];
55 const char *class_cast_cache[OBJECT_CLASS_CAST_CACHE];
56
57 ObjectUnparent *unparent;
58
59 GHashTable *properties;
60 };
61 typedef struct ChardevClass {
62 ObjectClass parent_class;
63
64 bool internal; /* TODO: eventually use TYPE_USER_CREATABLE */
65 void (*parse)(QemuOpts *opts, ChardevBackend *backend, Error **errp);
66
67 void (*open)(Chardev *chr, ChardevBackend *backend,
68 bool *be_opened, Error **errp);
69
70 int (*chr_write)(Chardev *s, const uint8_t *buf, int len);
71 int (*chr_sync_read)(Chardev *s, const uint8_t *buf, int len);
72 GSource *(*chr_add_watch)(Chardev *s, GIOCondition cond);
73 void (*chr_update_read_handler)(Chardev *s);
74 int (*chr_ioctl)(Chardev *s, int cmd, void *arg);
75 int (*get_msgfds)(Chardev *s, int* fds, int num);
76 int (*set_msgfds)(Chardev *s, int *fds, int num);
77 int (*chr_add_client)(Chardev *chr, int fd);
78 int (*chr_wait_connected)(Chardev *chr, Error **errp);
79 void (*chr_disconnect)(Chardev *chr);
80 void (*chr_accept_input)(Chardev *chr);
81 void (*chr_set_echo)(Chardev *chr, bool echo);
82 void (*chr_set_fe_open)(Chardev *chr, int fe_open);
83 void (*chr_be_event)(Chardev *s, int event);
84 /* Return 0 if succeeded, 1 if failed */
85 int (*chr_machine_done)(Chardev *chr);
86 } ChardevClass;
87 =========================================================================
88 print *((CharBackend *)0x55873895f4c0)->chr
89 $32 = {
90 parent_obj = {
91 class = 0x5587353beb40,
92 free = 0x7f59ebf707e0 <g_free>,
93 Python Exception <class 'gdb.error'> There is no member named keys.:
94 properties = 0x558735469b00,
95 ref = 1,
96 parent = 0x558735470960
97 },
98 chr_write_lock = {
99 lock = {
100 __data = {
101 __lock = 0,
102 __count = 0,
103 __owner = 0,
104 __nusers = 0,
105 __kind = 0,
106 __spins = 0,
107 __elision = 0,
108 __list = {
109 __prev = 0x0,
110 __next = 0x0
111 }
112 },
113 __size = '\000' <repeats 39 times>,
114 __align = 0
115 },
116 initialized = true
117 },
118 be = 0x55873895f4c0,
119 label = 0x5587353af7b0 "charserial0",
120 filename = 0x55873543fea0 "disconnected:unix:/dev/shm/kvm_unix_ch/dev-8f0d86,server",
121 logfd = -1,
122 be_open = 0,
123 gsource = 0x0,
124 gcontext = 0x0,
125 features = {1}
126 }
127
128
129 print ((CharBackend *)0x55873895f4c0)->chr
130 $27 = (Chardev *) 0x5587354645a0
131
132 print ((Object *)(0x5587354645a0))->class
133 $29 = (ObjectClass *) 0x5587353beb40
134
135 print (ChardevClass *)0x5587353beb40
136 (gdb) print *(ChardevClass *)0x5587353beb40
137 $31 = {
138 parent_class = {
139 type = 0x558735406300,
140 interfaces = 0x0,
141 object_cast_cache = {0x0, 0x0, 0x0, 0x0},
142 class_cast_cache = {0x0, 0x0, 0x0, 0x0},
143 unparent = 0x0,
144 Python Exception <class 'gdb.error'> There is no member named keys.:
145 properties = 0x558735444aa0
146 },
147 internal = false,
148 parse = 0x55873293a120 <qemu_chr_parse_socket>,
149 open = 0x55873293b210 <qmp_chardev_open_socket>,
150 chr_write = 0x55873293b130 <tcp_chr_write>,
151 chr_sync_read = 0x55873293b080 <tcp_chr_sync_read>,
152 chr_add_watch = 0x558732939860 <tcp_chr_add_watch>,
153 chr_update_read_handler = 0x55873293b740 <tcp_chr_update_read_handler>,
154 chr_ioctl = 0x0,
155 get_msgfds = 0x55873293a750 <tcp_get_msgfds>,
156 set_msgfds = 0x558732939f50 <tcp_set_msgfds>,
157 chr_add_client = 0x55873293bb10 <tcp_chr_add_client>,
158 chr_wait_connected = 0x55873293bb60 <tcp_chr_wait_connected>,
159 chr_disconnect = 0x55873293a9d0 <tcp_chr_disconnect>,
160 chr_accept_input = 0x0,
161 chr_set_echo = 0x0,
162 chr_set_fe_open = 0x0,
163 chr_be_event = 0x5587329333a0 <chr_be_event>,
164 chr_machine_done = 0x55873293b010 <tcp_chr_machine_done_hook>
165 }
166
167 ================================================================
168 static GSource *tcp_chr_add_watch(Chardev *chr, GIOCondition cond)
169 {
170 SocketChardev *s = SOCKET_CHARDEV(chr);
171 return qio_channel_create_watch(s->ioc, cond);
172 }
173
174
175
176
177 guint qemu_chr_fe_add_watch(CharBackend *be, GIOCondition cond,
178 GIOFunc func, void *user_data)
179 {
180 Chardev *s = be->chr;
181 GSource *src;
182 guint tag;
183
184 if (!s || CHARDEV_GET_CLASS(s)->chr_add_watch == NULL) {
185 return 0;
186 }
187
188 src = CHARDEV_GET_CLASS(s)->chr_add_watch(s, cond);
189 if (!src) {
190 return 0;
191 }
192
193 g_source_set_callback(src, (GSourceFunc)func, user_data, NULL);
194 tag = g_source_attach(src, s->gcontext);
195 g_source_unref(src);
196
197 return tag;
198 }
199 (gdb) bt
200 #0 0x00005587328b34b0 in object_get_class (obj=obj@entry=0x0) at qom/object.c:759
201 #1 0x0000558732946440 in qio_channel_create_watch (ioc=0x0, condition=(G_IO_OUT | G_IO_HUP)) at io/channel.c:280
202 #2 0x0000558732936577 in qemu_chr_fe_add_watch (be=be@entry=0x55873895f4c0, cond=cond@entry=(G_IO_OUT | G_IO_HUP), func=func@entry=
203 0x5587327b7700 <serial_watch_cb>, user_data=user_data@entry=0x55873895f4a0) at chardev/char-fe.c:355
204 #3 0x00005587327b7a97 in serial_post_load (opaque=0x55873895f4a0, version_id=<optimized out>) at hw/char/serial.c:679
205 #4 0x000055873285eb47 in vmstate_load_state (f=f@entry=0x558738c26000, vmsd=0x558732ff4d40 <vmstate_serial>, opaque=0x55873895f4a0, version_id=3) at migration/vmstate.c:165
206 #5 0x000055873285ec5c in vmstate_load_state (f=0x558738c26000, vmsd=0x558732ff50c0 <vmstate_isa_serial>, opaque=0x55873895f400, version_id=3) at migration/vmstate.c:137
207 #6 0x000055873285abf5 in qemu_loadvm_state_main (mis=<optimized out>, f=0x558738c26000) at migration/savevm.c:1970
208 #7 0x000055873285abf5 in qemu_loadvm_state_main (f=f@entry=0x558738c26000, mis=0x55873320dc00 <mis_current.30332>) at migration/savevm.c:2078
209 #8 0x000055873285ca2e in qemu_loadvm_state (f=0x558738c26000) at migration/savevm.c:2162
210 #9 0x0000558732856bf2 in process_incoming_migration_co (opaque=<optimized out>) at migration/migration.c:388
211 #10 0x00005587329a944a in coroutine_trampoline (i0=<optimized out>, i1=<optimized out>) at util/coroutine-ucontext.c:116
212 #11 0x00007f59d3086190 in __start_context () at /lib64/libc.so.6
213 #12 0x00007ffecf01f990 in ()
214 #13 0x0000000000000000 in ()
215
216 修复办法:
217
218 diff -Nuar a/chardev/char-socket.c b/chardev/char-socket.c
219 --- a/chardev/char-socket.c 2023-03-14 20:36:09.910360722 +0800
220 +++ b/chardev/char-socket.c 2023-03-14 20:36:34.551591389 +0800
221 @@ -348,6 +348,9 @@
222 static GSource *tcp_chr_add_watch(Chardev *chr, GIOCondition cond)
223 {
224 SocketChardev *s = SOCKET_CHARDEV(chr);
225 + if (!s->ioc) {
226 + return NULL;
227 + }
228 return qio_channel_create_watch(s->ioc, cond);
229 }
230
231 =============================================================
232 重新编译rpm包后测试,需要测试配合迁移测试
参考补丁:版本5.20修复
https://gitlab.com/qemu-project/qemu/-/commit/6585b1627899a3fcaf1cf62bfb659b04371ca9ec
https://gitlab.com/qemu-project/qemu/-/tree/6585b1627899a3fcaf1cf62bfb659b04371ca9ec
标签：8.1,__,0x0,int,kvm,chr,Chardev,qemu,class From： https://www.cnblogs.com/maojun1998/p/17216763.html