linux-kernel - Re: [PATCH V2 0/7] cpufreq: governors: Fix ABBA lockups

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Date:	Thu, 4 Feb 2016 17:47:27 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Juri Lelli <juri.lelli@....com>
Cc:	Rafael Wysocki <rjw@...ysocki.net>, linaro-kernel@...ts.linaro.org,
	linux-pm@...r.kernel.org, skannan@...eaurora.org,
	peterz@...radead.org, mturquette@...libre.com,
	steve.muckle@...aro.org, vincent.guittot@...aro.org,
	morten.rasmussen@....com, dietmar.eggemann@....com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 0/7] cpufreq: governors: Fix ABBA lockups

On 04-02-16, 11:54, Viresh Kumar wrote:
> From the code I still failed to understand this since sometime back
> and I something just caught my eyes and the 6th patch needs this
> fixup:
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 7bc8a5ed97e5..ac3348ecde7b 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -1351,7 +1351,7 @@ static void cpufreq_offline(unsigned int cpu)
>                                 pr_err("%s: Failed to start governor\n", __func__);
>                 }
>  
> -               return;
> +               goto unlock;
>         }
>  
>         if (cpufreq_driver->stop_cpu)
> @@ -1373,6 +1373,8 @@ static void cpufreq_offline(unsigned int cpu)
>                 cpufreq_driver->exit(policy);
>                 policy->freq_table = NULL;
>         }
> +
> +unlock:
>         up_write(&policy->rwsem);
>  }
> 
> I tried the basic tests using './runme' and they aren't reporting the
> same lockdep now. And yes, your lockdep occurred on my exynos board as
> well :)
> 
> I have re-pushed my patches again to the same branch. All 7 look fine
> to me now :)

FWIW, Juri has reported on IRC that the above diff fixed the lockdep
he reported yesterday and all the 7 patches are working fine on his
test machine, Juno.

-- 
viresh