The yank feature allows to recover from hanging qemu by "yanking" at various parts. Other qemu systems can register yank functions which will be called by the 'yank' out-of-band qmp command.
Signed-off-by: Lukas Straub <lukasstra...@web.de> --- qapi/misc.json | 15 ++++++++++ softmmu/vl.c | 2 ++ yank.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++ yank.h | 12 ++++++++ 4 files changed, 104 insertions(+) create mode 100644 yank.c create mode 100644 yank.h diff --git a/qapi/misc.json b/qapi/misc.json index 99b90ac80b..de1ee494ae 100644 --- a/qapi/misc.json +++ b/qapi/misc.json @@ -1550,3 +1550,18 @@ ## { 'command': 'query-vm-generation-id', 'returns': 'GuidInfo' } +## +# @yank: +# +# Recover from hanging qemu by calling yank functions. +# +# Returns: nothing. +# +# Example: +# +# -> { "execute": "yank" } +# <- { "return": {} } +# +# Since: 5.1 +## +{ 'command': 'yank', 'allow-oob': true } diff --git a/softmmu/vl.c b/softmmu/vl.c index 32c0047889..5d99749d29 100644 --- a/softmmu/vl.c +++ b/softmmu/vl.c @@ -112,6 +112,7 @@ #include "qapi/qmp/qerror.h" #include "sysemu/iothread.h" #include "qemu/guest-random.h" +#include "yank.h" #define MAX_VIRTIO_CONSOLES 1 @@ -2906,6 +2907,7 @@ void qemu_init(int argc, char **argv, char **envp) precopy_infrastructure_init(); postcopy_infrastructure_init(); monitor_init_globals(); + yank_init(); if (qcrypto_init(&err) < 0) { error_reportf_err(err, "cannot initialize crypto: "); diff --git a/yank.c b/yank.c new file mode 100644 index 0000000000..cefbfd8ab5 --- /dev/null +++ b/yank.c @@ -0,0 +1,75 @@ +/* + * QEMU yank feature + * + * Copyright (c) Lukas Straub <lukasstra...@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 "yank.h" + +struct YankFuncAndParam { + YankFn *func; + void *opaque; + QLIST_ENTRY(YankFuncAndParam) next; +}; + +static QemuMutex lock; +static QLIST_HEAD(qlisthead, YankFuncAndParam) head + = QLIST_HEAD_INITIALIZER(head); + +void yank_register_function(YankFn *func, void *opaque) +{ + struct YankFuncAndParam *tmp = g_malloc(sizeof(struct YankFuncAndParam)); + tmp->func = func; + tmp->opaque = opaque; + + qemu_mutex_lock(&lock); + QLIST_INSERT_HEAD(&head, tmp, next); + qemu_mutex_unlock(&lock); +} + +void yank_unregister_function(YankFn *func, void *opaque) +{ + qemu_mutex_lock(&lock); + + struct YankFuncAndParam *tmp; + QLIST_FOREACH(tmp, &head, next) { + if (tmp->func == func && tmp->opaque == opaque) { + QLIST_REMOVE(tmp, next); + g_free(tmp); + qemu_mutex_unlock(&lock); + return; + } + } + + abort(); +} + +void yank_call_functions(void) +{ + qemu_mutex_lock(&lock); + + struct YankFuncAndParam *tmp; + QLIST_FOREACH(tmp, &head, next) { + tmp->func(tmp->opaque); + } + + qemu_mutex_unlock(&lock); +} + +void qmp_yank(Error **errp) +{ + yank_call_functions(); +} + +void yank_init(void) +{ + qemu_mutex_init(&lock); + QLIST_INIT(&head); +} diff --git a/yank.h b/yank.h new file mode 100644 index 0000000000..7376224219 --- /dev/null +++ b/yank.h @@ -0,0 +1,12 @@ + +#ifndef YANK_H +#define YANK_H + +typedef void (YankFn) (void *opaque); + +void yank_register_function(YankFn *func, void *opaque); +void yank_unregister_function(YankFn *func, void *opaque); +void yank_call_functions(void); +void yank_init(void); +void qmp_yank(Error **errp); +#endif -- 2.20.1
pgpWL0xCpizRu.pgp
Description: OpenPGP digital signature