Denis Plotnikov writes:
> This is needed to keep sending DEVICE_DELETED events on qemu cleanup.
> The event may happen in the rcu thread and we're going to flush the rcu queue
> explicitly before qemu exiting in the next patch. So move the monitor
> destruction to the very end of qemu cleanup to be able to send all the events.
>
> Signed-off-by: Denis Plotnikov
> ---
> monitor/monitor.c | 6 ++
> softmmu/runstate.c | 2 +-
> 2 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/monitor/monitor.c b/monitor/monitor.c
> index 21c7a68758f5..b04ae4850db2 100644
> --- a/monitor/monitor.c
> +++ b/monitor/monitor.c
> @@ -605,11 +605,17 @@ void monitor_data_init(Monitor *mon, bool is_qmp, bool
> skip_flush,
> mon->outbuf = g_string_new(NULL);
> mon->skip_flush = skip_flush;
> mon->use_io_thread = use_io_thread;
> +/*
> + * take an extra ref to prevent monitor's chardev
> + * from destroying in qemu_chr_cleanup()
> + */
> +object_ref(OBJECT(mon->chr.chr));
I'm not sure we need the comment in the long run.
Taking a reference changes mon->chr.chr from soft reference to hard
reference. Feels right to me.
Note that mon->chr.chr isn't set here, but earlier. Unlike the other
parts of @mon. Because of this it starts as a soft reference, and
hardens only here.
It's set in three places:
1. monitor_init_hmp():
if (!qemu_chr_fe_init(>common.chr, chr, errp)) {
g_free(mon);
return;
}
monitor_data_init(>common, false, false, false);
2. monitor_init_qmp():
if (!qemu_chr_fe_init(>common.chr, chr, errp)) {
g_free(mon);
return;
}
qemu_chr_fe_set_echo(>common.chr, true);
/* Note: we run QMP monitor in I/O thread when @chr supports that */
monitor_data_init(>common, true, false,
qemu_chr_has_feature(chr, QEMU_CHAR_FEATURE_GCONTEXT));
3. qmp_human_monitor_command()
MonitorHMP hmp = {};
monitor_data_init(, false, true, false);
hmp.common.chr.chr remains null here. Works, because
object_ref(OBJECT(NULL)) and object_unref(OBJECT(NULL)) do nothing.
Slightly cleaner, I think: pass the character device as an argument to
monitor_data_init(), take a reference and store it in mon->chr.chr
there.
> }
>
> void monitor_data_destroy(Monitor *mon)
> {
> g_free(mon->mon_cpu_path);
> +object_unref(OBJECT(mon->chr.chr));
> qemu_chr_fe_deinit(>chr, false);
> if (monitor_is_qmp(mon)) {
> monitor_data_destroy_qmp(container_of(mon, MonitorQMP, common));
> diff --git a/softmmu/runstate.c b/softmmu/runstate.c
> index 10d9b7365aa7..8d29dd2c00e2 100644
> --- a/softmmu/runstate.c
> +++ b/softmmu/runstate.c
> @@ -819,8 +819,8 @@ void qemu_cleanup(void)
> tpm_cleanup();
> net_cleanup();
> audio_cleanup();
> -monitor_cleanup();
> qemu_chr_cleanup();
> user_creatable_cleanup();
> +monitor_cleanup();
> /* TODO: unref root container, check all devices are ok */
> }
Monitor cleanup now runs with character devices that have been
"unparented" from the QOM tree. Paolo, is that okay?
