On Mon, Jul 03, 2017 at 10:44:06AM +0800, Peter Xu wrote: > Currently drive_init_func() may call migrate_get_current() while the > migrate object is still not ready yet at that time. Move the migration > object init earlier, along with the global properties, right after > acceleration init. > > This fixes a breakage for iotest 055, which caused an assertion failure. > > Reported-by: Max Reitz <mre...@redhat.com> > Reported-by: Philippe Mathieu-Daudé <f4...@amsat.org> > Fixes: 3df663 ("migration: move only_migratable to MigrationState") > Signed-off-by: Peter Xu <pet...@redhat.com> > --- > vl.c | 24 ++++++++++++------------ > 1 file changed, 12 insertions(+), 12 deletions(-) > > diff --git a/vl.c b/vl.c > index 0c497a3..2ae4313 100644 > --- a/vl.c > +++ b/vl.c > @@ -4414,6 +4414,18 @@ int main(int argc, char **argv, char **envp) > > configure_accelerator(current_machine); > > + /* > + * Register all the global properties, including accel properties, > + * machine properties, and user-specified ones. > + */ > + register_global_properties(current_machine); > + > + /* > + * Migration object can only be created after global properties > + * are applied correctly. > + */ > + migration_object_init(); > +
So, things that might introduce bugs here are: 1) Unexpected qdev_prop_register_global() calls between this place and the original register_global_properties() call (that would now happen in a different order). 2) register_global_properties() seeing a different global property list because it is being called earlier. 2.1) AccelClass::global_props is statically defined and will be the same here. Not a problem. 2.2) MachineClass::compat_props: same as above. 2.3) user-provided global properties: we need to ensure all properties in the "global" QemuOpts section are already available at this point. To ensure (1) is not a problem, we need to check all calls for qdev_prop_register_global(). The callers are: * configure_rtc() - Called very early, when parsing command-line options. Not a problem.[1] * global_init_func() * Called by user_register_global_props() * Called by register_global_properties(). - That's the code we're moving. Not a problem. * QEMU_OPTION_rtc_td_hack case in main() - Called very early, when parsing command-line options. Not a problem.[1] * QEMU_OPTION_no_kvm_pit_reinjection case in main() - Called very early, when parsing command-line options. Not a problem.[1] * register_compat_prop() * Called by machine_register_compat_props() * Called by register_global_properties(). - That's the code we're moving. Not a problem. * Called by machine_register_compat_for_subclass() * Called by machine_register_compat_props() (see above) * Called by register_compat_props_array() * Called by accel_register_compat_props() * Called by register_global_properties(). - That's the code we're moving. Not a problem. * qdev_prop_register_global_list() - Used only by unit test code. * cpu_common_parse_features() - Used when initializing CPUs, which is done much later, when machine_run_board_init() is called (or when -device is handled by device_init_func()). Not a problem.[2] * x86_cpu_parse_featurestr() - Same as above. To ensure (2.3) is not a problem, we need to look for references to qemu_find_opts("global") or qemu_global_opts. They are: * user_register_global_props() - This is the code we're moving. Not a problem. * default_driver_check() call at main() - This happens earlier, before the code we're moving. Not a problem. * qemu_global_option() - Called very early, when parsing command-line options. Not a problem. So the code reordering looks OK. Reviewed-by: Eduardo Habkost <ehabk...@redhat.com> Notes about things we need to fix in the future: [1] I think they should be replaced by qemu_global_option() calls, though. [2] This is a fragile portion of the global property code and should be eventually moved to the command-line parsing section of main(). > if (qtest_chrdev) { > qtest_init(qtest_chrdev, qtest_log, &error_fatal); > } > @@ -4595,18 +4607,6 @@ int main(int argc, char **argv, char **envp) > exit (i == 1 ? 1 : 0); > } > > - /* > - * Register all the global properties, including accel properties, > - * machine properties, and user-specified ones. > - */ > - register_global_properties(current_machine); > - > - /* > - * Migration object can only be created after global properties > - * are applied correctly. > - */ > - migration_object_init(); > - > /* This checkpoint is required by replay to separate prior clock > reading from the other reads, because timer polling functions query > clock values from the log. */ > -- > 2.7.4 > -- Eduardo