Re: [PATCH] cpufreq: schedutil: Avoid missing updates for one-CPU policies

[Joel Fernandes]

On Wed, May 23, 2018 at 11:47:45AM +0200, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> 
> Commit 152db033d775 (schedutil: Allow cpufreq requests to be made
> even when kthread kicked) made changes to prevent utilization updates
> from being discarded during processing a previous request, but it
> left a small window in which that still can happen in the one-CPU
> policy case.  Namely, updates coming in after setting work_in_progress
> in sugov_update_commit() and clearing it in sugov_work() will still
> be dropped due to the work_in_progress check in sugov_update_single().
> 
> To close that window, rearrange the code so as to acquire the update
> lock around the deferred update branch in sugov_update_single()
> and drop the work_in_progress check from it.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

Reviewed-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>

thanks,

 - Joel