linux-kernel - Re: [PATCH v2 20/20] cpufreq: Return zero on success in boost sw setting

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Date:   Mon, 18 May 2020 15:54:15 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Serge Semin <Sergey.Semin@...kalelectronics.ru>,
        Serge Semin <fancer.lancer@...il.com>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Alexey Malahov <Alexey.Malahov@...kalelectronics.ru>,
        Paul Burton <paulburton@...nel.org>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Arnd Bergmann <arnd@...db.de>,
        Rob Herring <robh+dt@...nel.org>, linux-mips@...r.kernel.org,
        devicetree@...r.kernel.org, stable@...r.kernel.org,
        Frederic Weisbecker <frederic@...nel.org>,
        Ingo Molnar <mingo@...nel.org>, Yue Hu <huyue2@...ong.com>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 20/20] cpufreq: Return zero on success in boost sw
 setting

On 18-05-20, 12:22, Rafael J. Wysocki wrote:
> On Monday, May 18, 2020 12:11:09 PM CEST Viresh Kumar wrote:
> > On 18-05-20, 11:53, Rafael J. Wysocki wrote:
> > > That said if you really only want it to return 0 on success, you may as well
> > > add a ret = 0; statement (with a comment explaining why it is needed) after
> > > the last break in the loop.
> > 
> > That can be done as well, but will be a bit less efficient as the loop
> > will execute once for each policy, and so the statement will run
> > multiple times. Though it isn't going to add any significant latency
> > in the code.
> 
> Right.
> 
> However, the logic in this entire function looks somewhat less than
> straightforward to me, because it looks like it should return an
> error on the first policy without a frequency table (having a frequency
> table depends on the driver and that is the same for all policies, so it
> is pointless to iterate any further in that case).
> 
> Also, the error should not be -EINVAL, because that means "invalid
> argument" which would be the state value.
> 
> So I would do something like this:
> 
> ---
>  drivers/cpufreq/cpufreq.c |   11 ++++++-----
>  1 file changed, 6 insertions(+), 5 deletions(-)
> 
> Index: linux-pm/drivers/cpufreq/cpufreq.c
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/cpufreq.c
> +++ linux-pm/drivers/cpufreq/cpufreq.c
> @@ -2535,26 +2535,27 @@ EXPORT_SYMBOL_GPL(cpufreq_update_limits)
>  static int cpufreq_boost_set_sw(int state)
>  {
>  	struct cpufreq_policy *policy;
> -	int ret = -EINVAL;
>  
>  	for_each_active_policy(policy) {
> +		int ret;
> +
>  		if (!policy->freq_table)
> -			continue;
> +			return -ENXIO;
>  
>  		ret = cpufreq_frequency_table_cpuinfo(policy,
>  						      policy->freq_table);
>  		if (ret) {
>  			pr_err("%s: Policy frequency update failed\n",
>  			       __func__);
> -			break;
> +			return ret;
>  		}
>  
>  		ret = freq_qos_update_request(policy->max_freq_req, policy->max);
>  		if (ret < 0)
> -			break;
> +			return ret;
>  	}
>  
> -	return ret;
> +	return 0;
>  }
>  
>  int cpufreq_boost_trigger_state(int state)

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

-- 
viresh