Re: [PATCH v6 46/52] opp: Put interconnect paths outside of opp_table_lock

Viresh Kumar
2020-10-29T00:32:59Z

On 27-10-20, 23:26, Dmitry Osipenko wrote:
> 27.10.2020 08:10, Viresh Kumar пишет:
> > On 26-10-20, 01:17, Dmitry Osipenko wrote:
> >> This patch fixes lockup which happens when OPP table is released if
> >> interconnect provider uses OPP in the icc_provider->set() callback
> >> and bandwidth of the ICC path is set to 0 by the ICC core when path
> >> is released. The icc_put() doesn't need the opp_table_lock protection,
> >> hence let's move it outside of the lock in order to resolve the problem.
> >>
> >> In particular this fixes tegra-devfreq driver lockup on trying to unload
> >> the driver module. The devfreq driver uses OPP-bandwidth API and its ICC
> >> provider also uses OPP for DVFS, hence they both take same opp_table_lock
> >> when OPP table of the devfreq is released.
> >>
> >> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> >> ---
> ...
> >
> > Never make such _fixes_ part of such a big patchset. Always send them
> > separately.
>
> Perhaps it's not obvious from the commit description that this patch
> doesn't fix any known problems of the current mainline kernel and it's
> needed only for the new patches.

No, I understood that we started getting the warning now only after
some other patches of yours. Nevertheless, it should be considered as
a fix only as that generated lockdep because of locking placement. And
so sending such stuff separately is better as that allows people to
apply it fast.

> > Having said that, I already have a patch with me which shall fix it for you as
> > well:
>
> I see that yours fix is already applied, thanks!

I hope it worked for you. Thanks.

--
viresh