[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-devel] [PATCH 2/4] vl: move global property, migrate init earl
From: |
Eduardo Habkost |
Subject: |
Re: [Qemu-devel] [PATCH 2/4] vl: move global property, migrate init earlier |
Date: |
Mon, 3 Jul 2017 11:59:03 -0300 |
User-agent: |
Mutt/1.8.0 (2017-02-23) |
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 <address@hidden>
> Reported-by: Philippe Mathieu-Daudé <address@hidden>
> Fixes: 3df663 ("migration: move only_migratable to MigrationState")
> Signed-off-by: Peter Xu <address@hidden>
> ---
> 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 <address@hidden>
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