On Thu, Nov 29, 2018 at 11:40:57AM +0800, Wei Wang wrote:
I think this precopy notifier callchain is expected to be used only for
the precopy mode. Postcopy has its dedicated notifier callchain that
users could use.
How about changing the migrate_postcopy() check to "ms->start_postcopy":
bool migration_postcopy_start(void)
{
MigrationState *s;
s = migrate_get_current();
return atomic_read(&s->start_postcopy);
}
static void precopy_notify(PrecopyNotifyReason reason)
{
if (migration_postcopy_start())
return;
notifier_list_notify(&precopy_notifier_list, &reason);
}
If postcopy started with precopy, the precopy optimization feature
could still be used until it switches to the postcopy mode.
I'm not sure we can use start_postcopy. It's a variable being set in
the QMP handler but it does not mean postcopy has started. I'm afraid
there can be race where it's still precopy but the variable is set so
event could be missed...