Re: [PATCH V2 09/10] x86/resctrl: Pseudo-lock portions of multiple resources

Borislav Petkov
2019-08-09T07:37:25Z

On Thu, Aug 08, 2019 at 01:13:46PM -0700, Reinette Chatre wrote:
> There is a locking order dependency between cpu_hotplug_lock and
> rdtgroup_mutex (cpu_hotplug_lock before rdtgroup_mutex) that has to be
> maintained. To do so in this flow you will find cpus_read_lock() in
> rdtgroup_schemata_write(), so quite a distance from where it is needed.
>
> Perhaps I should add a comment at the location where the lock is
> required to document where the lock is obtained?

Even better - you can add:

lockdep_assert_cpus_held();

above it which documents *and* checks too. :-)

--
Regards/Gruss,
Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.