From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Pan Xinhui <xinhuix.pan@intel.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        "linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        "yanmin_zhang@linux.intel.com" <yanmin_zhang@linux.intel.com>,
        "mnipxh@163.com" <mnipxh@163.com>
Subject: Re: [PATCH] acpi-cpufreq: Add a miss ifdef CONFIG_X86_ACPI_CPUFREQ_CPB
Date: Tue, 14 Jul 2015 01:26:28 +0200
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On Monday, July 13, 2015 02:33:08 PM Pan Xinhui wrote:
> hi, Rafeal
> 	thanks for your reply. :)
> 
> On 2015年07月11日 04:44, Rafael J. Wysocki wrote:
> > Hi,
> > 
> > On Fri, Jul 10, 2015 at 7:50 AM, Pan Xinhui <xinhuix.pan@intel.com> wrote:
> >>
> >> If CONFIG_X86_ACPI_CPUFREQ_CPB has not been defined, the placeholder for
> >> cpb is not needed. Add ifdef around it.
> >>
> >> Signed-off-by: Pan Xinhui <xinhuix.pan@intel.com>
> >> ---
> >>  drivers/cpufreq/acpi-cpufreq.c | 2 ++
> >>  1 file changed, 2 insertions(+)
> >>
> >> diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
> >> index e7fcaa6..314a19e 100644
> >> --- a/drivers/cpufreq/acpi-cpufreq.c
> >> +++ b/drivers/cpufreq/acpi-cpufreq.c
> >> @@ -884,7 +884,9 @@ static int acpi_cpufreq_resume(struct cpufreq_policy *policy)
> >>  static struct freq_attr *acpi_cpufreq_attr[] = {
> >>         &cpufreq_freq_attr_scaling_available_freqs,
> >>         &freqdomain_cpus,
> >> +#ifdef CONFIG_X86_ACPI_CPUFREQ_CPB
> >>         NULL,   /* this is a placeholder for cpb, do not remove */
> >> +#endif
> > 
> > Adding the ifdef here doesn't change anything, because the next NULL
> > will play the role of the one you've just #ifdefed and the structure
> > will be filled with zeros from that point on anyway.
> > 
> Yes, adding ifdef here does not change any binary codes. But I want to make the codes more readable. :)
> Patch author has noticed two *NULL* here would confuse people, especially who first read this acpi-cpufreq.c file
> From code style point, it would be better to have #ifdef around it. 

Not really.

Why don't you simply drop *both* NULLs?


> 
> > You'd need to #ifdef it in the struct freq_attr definition, but I'm
> > not sure it's worth the effort.
> > 
> 
> struct freq_attr *cpb* is defined in #ifdef section. :)

Ah, OK.


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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