Re: [PATCH] cpufreq: scpi/scmi: Fix freeing of dynamic OPPs

From: Sudeep Holla
Date: Fri Jan 04 2019 - 06:01:53 EST

On Fri, Jan 04, 2019 at 03:14:33PM +0530, Viresh Kumar wrote:
> Since the commit 2a4eb7358aba ("OPP: Don't remove dynamic OPPs from
> _dev_pm_opp_remove_table()"), dynamically created OPP aren't
> automatically removed anymore by dev_pm_opp_cpumask_remove_table(). This
> affects the scpi and scmi cpufreq drivers which no longer free OPPs on
> failures or on invocations of the policy->exit() callback.
> Create a generic OPP helper dev_pm_opp_remove_all_dynamic() which can be
> called from these drivers instead of dev_pm_opp_cpumask_remove_table().
> In dev_pm_opp_remove_all_dynamic(), we need to make sure that the
> opp_list isn't getting accessed simultaneously from other parts of the
> OPP core while the helper is freeing dynamic OPPs, i.e. we can't drop
> the opp_table->lock while traversing through the OPP list. And to
> accomplish that, this patch also creates _opp_kref_release_unlocked()
> which can be called from this new helper with the opp_table lock already
> held.

I did test it but since I couldn't reproduce the original issue, my
tested-by is not that worth. Anyways the changes look fine to me.

Reviewed-by: Sudeep Holla <sudeep.holla@xxxxxxx>