linux-kernel - Re: [PATCH] cpufreq: Fix policy initialization for internal governor drivers

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Message-ID: <20200227051923.rh6xtq3t2bkoqroh@vireshk-i7>
Date:   Thu, 27 Feb 2020 10:49:23 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Linux PM <linux-pm@...r.kernel.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Artem Bityutskiy <dedekind1@...il.com>
Subject: Re: [PATCH] cpufreq: Fix policy initialization for internal governor
 drivers

On 26-02-20, 22:39, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> Before commit 1e4f63aecb53 ("cpufreq: Avoid creating excessively
> large stack frames") the initial value of the policy field in struct
> cpufreq_policy set by the driver's ->init() callback was implicitly
> passed from cpufreq_init_policy() to cpufreq_set_policy() if the
> default governor was neither "performance" nor "powersave".  After
> that commit, however, cpufreq_init_policy() must take that case into
> consideration explicitly and handle it as appropriate, so make that
> happen.
> 
> Fixes: 1e4f63aecb53 ("cpufreq: Avoid creating excessively large stack frames")
> Link: https://lore.kernel.org/linux-pm/39fb762880c27da110086741315ca8b111d781cd.camel@gmail.com/
> Reported-by: Artem Bityutskiy <dedekind1@...il.com>
> Cc: 5.4+ <stable@...r.kernel.org> # 5.4+
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
> 
> Note that I'm going to fast-track this patch for 5.6-rc4 which means that
> it will go into my linux-next branch as soon as it shows up in the lists.
> 
> Thanks and sorry for the breakage!
> 
> ---
>  drivers/cpufreq/cpufreq.c |   14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> Index: linux-pm/drivers/cpufreq/cpufreq.c
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/cpufreq.c
> +++ linux-pm/drivers/cpufreq/cpufreq.c
> @@ -1076,9 +1076,17 @@ static int cpufreq_init_policy(struct cp
>  			pol = policy->last_policy;
>  		} else if (def_gov) {
>  			pol = cpufreq_parse_policy(def_gov->name);
> -		} else {
> -			return -ENODATA;
> +			/*
> +			 * In case the default governor is neiter "performance"
> +			 * nor "powersave", fall back to the initial policy
> +			 * value set by the driver.
> +			 */
> +			if (pol == CPUFREQ_POLICY_UNKNOWN)
> +				pol = policy->policy;
>  		}
> +		if (pol != CPUFREQ_POLICY_PERFORMANCE &&
> +		    pol != CPUFREQ_POLICY_POWERSAVE)
> +			return -ENODATA;
>  	}
>  
>  	return cpufreq_set_policy(policy, gov, pol);

Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

-- 
viresh