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[PATCH 2/2] Support monitor chardev hotswap with QMP
From: |
Li Zhang |
Subject: |
[PATCH 2/2] Support monitor chardev hotswap with QMP |
Date: |
Mon, 15 Mar 2021 18:06:36 +0100 |
From: Li Zhang <li.zhang@cloud.ionos.com>
For some scenarios, it needs to hot-add a monitor device.
But QEMU doesn't support hotplug yet. It also works by adding
a monitor with null backend by default and then change its
backend to socket by QMP command "chardev-change".
So this patch is to support monitor chardev hotswap with QMP.
Signed-off-by: Li Zhang <li.zhang@cloud.ionos.com>
---
monitor/monitor-internal.h | 3 +++
monitor/monitor.c | 2 +-
monitor/qmp.c | 42 +++++++++++++++++++++++++++++++++++---
3 files changed, 43 insertions(+), 4 deletions(-)
diff --git a/monitor/monitor-internal.h b/monitor/monitor-internal.h
index 40903d6386..2df6dd21de 100644
--- a/monitor/monitor-internal.h
+++ b/monitor/monitor-internal.h
@@ -186,4 +186,7 @@ int hmp_compare_cmd(const char *name, const char *list);
void qmp_query_qmp_schema(QDict *qdict, QObject **ret_data,
Error **errp);
+gboolean monitor_unblocked(GIOChannel *chan, GIOCondition cond,
+ void *opaque);
+
#endif
diff --git a/monitor/monitor.c b/monitor/monitor.c
index e94f532cf5..2d255bab18 100644
--- a/monitor/monitor.c
+++ b/monitor/monitor.c
@@ -157,7 +157,7 @@ static inline bool monitor_is_hmp_non_interactive(const
Monitor *mon)
static void monitor_flush_locked(Monitor *mon);
-static gboolean monitor_unblocked(GIOChannel *chan, GIOCondition cond,
+gboolean monitor_unblocked(GIOChannel *chan, GIOCondition cond,
void *opaque)
{
Monitor *mon = opaque;
diff --git a/monitor/qmp.c b/monitor/qmp.c
index 2326bd7f9b..55cfb230d9 100644
--- a/monitor/qmp.c
+++ b/monitor/qmp.c
@@ -44,6 +44,7 @@ struct QMPRequest {
Error *err;
};
typedef struct QMPRequest QMPRequest;
+static void monitor_qmp_set_handlers_bh(void *opaque);
QmpCommandList qmp_commands, qmp_cap_negotiation_commands;
@@ -480,7 +481,35 @@ void monitor_data_destroy_qmp(MonitorQMP *mon)
g_queue_free(mon->qmp_requests);
}
-static void monitor_qmp_setup_handlers_bh(void *opaque)
+static int monitor_qmp_change(void *opaque)
+{
+ MonitorQMP *mon = opaque;
+
+ mon->common.use_io_thread =
+ qemu_chr_has_feature(mon->common.chr.chr, QEMU_CHAR_FEATURE_GCONTEXT);
+
+ if (mon->common.use_io_thread) {
+ aio_bh_schedule_oneshot(iothread_get_aio_context(mon_iothread),
+ monitor_qmp_set_handlers_bh, mon);
+ } else {
+ qemu_chr_fe_set_handlers(&mon->common.chr, monitor_can_read,
+ monitor_qmp_read, monitor_qmp_event,
+ monitor_qmp_change, &mon->common, NULL, true);
+ }
+
+ if (mon->common.out_watch) {
+ g_source_remove(mon->common.out_watch);
+ qemu_mutex_lock(&mon->common.mon_lock);
+ mon->common.out_watch =
+ qemu_chr_fe_add_watch(&mon->common.chr, G_IO_OUT | G_IO_HUP,
+ monitor_unblocked, &mon->common);
+ qemu_mutex_unlock(&mon->common.mon_lock);
+ }
+
+ return 0;
+}
+
+static void monitor_qmp_set_handlers_bh(void *opaque)
{
MonitorQMP *mon = opaque;
GMainContext *context;
@@ -490,7 +519,14 @@ static void monitor_qmp_setup_handlers_bh(void *opaque)
assert(context);
qemu_chr_fe_set_handlers(&mon->common.chr, monitor_can_read,
monitor_qmp_read, monitor_qmp_event,
- NULL, &mon->common, context, true);
+ monitor_qmp_change, &mon->common, context, true);
+
+}
+
+static void monitor_qmp_setup_handlers_bh(void *opaque)
+{
+ MonitorQMP *mon = opaque;
+ monitor_qmp_set_handlers_bh(mon);
monitor_list_append(&mon->common);
}
@@ -531,7 +567,7 @@ void monitor_init_qmp(Chardev *chr, bool pretty, Error
**errp)
} else {
qemu_chr_fe_set_handlers(&mon->common.chr, monitor_can_read,
monitor_qmp_read, monitor_qmp_event,
- NULL, &mon->common, NULL, true);
+ monitor_qmp_change, &mon->common, NULL, true);
monitor_list_append(&mon->common);
}
}
--
2.25.1
Re: [PATCH 1/2] Fix the segment fault when calling yank_register_instance, Lukas Straub, 2021/03/17
Re: [PATCH 1/2] Fix the segment fault when calling yank_register_instance, Markus Armbruster, 2021/03/26