Re: [PATCH 1/3] cpufreq: stats: Remove redundant cpufreq_cpu_get() call

[Saravana Kannan]

On 02/25/2014 09:06 PM, Viresh Kumar wrote:
> On 26 February 2014 09:08, Saravana Kannan <skannan@xxxxxxxxxxxxxx> wrote:
> > __cpufreq_stats_create_table always gets pass the valid and real policy
> > struct. So, there's no need to call cpufreq_cpu_get() to get the policy
> > again.
> >
> > Change-Id: I0136b3e67018ee3af2335906407f55d8c6219f71
>
> ??
>
> > Signed-off-by: Saravana Kannan <skannan@xxxxxxxxxxxxxx>
> > ---
> >
> > Viresh/Rafael,
> >
> > These 3 patches is the approximate code I have in mind.
> >
> > Approximate because:
> > * I inserted one question as a comment into the code.
> > * If the patch doesn't have any bugs, the plan is to remove
> >    cpufreq_generic_get() and references to it.
> >
> > This takes care of the "don't advertise before it's ready for use" rule.
> >
> > Viresh,
> >
> > I think the locking updates needs to be done in addition to this.
> >
> > Regards,
> > Saravana
> >
> >   drivers/cpufreq/cpufreq_stats.c | 12 +-----------
> >   1 file changed, 1 insertion(+), 11 deletions(-)
> >
> > diff --git a/drivers/cpufreq/cpufreq_stats.c b/drivers/cpufreq/cpufreq_stats.c
> > index 5793e14..e4bd27f 100644
> > --- a/drivers/cpufreq/cpufreq_stats.c
> > +++ b/drivers/cpufreq/cpufreq_stats.c
> > @@ -185,7 +185,6 @@ static int __cpufreq_stats_create_table(struct cpufreq_policy *policy,
> >   {
> >          unsigned int i, j, count = 0, ret = 0;
> >          struct cpufreq_stats *stat;
> > -       struct cpufreq_policy *current_policy;
> >          unsigned int alloc_size;
> >          unsigned int cpu = policy->cpu;
> >          if (per_cpu(cpufreq_stats_table, cpu))
> > @@ -194,13 +193,7 @@ static int __cpufreq_stats_create_table(struct cpufreq_policy *policy,
> >          if ((stat) == NULL)
> >                  return -ENOMEM;
> >
> > -       current_policy = cpufreq_cpu_get(cpu);
> > -       if (current_policy == NULL) {
> > -               ret = -EINVAL;
> > -               goto error_get_fail;
> > -       }
> > -
> > -       ret = sysfs_create_group(&current_policy->kobj, &stats_attr_group);
> > +       ret = sysfs_create_group(&policy->kobj, &stats_attr_group);
> >          if (ret)
> >                  goto error_out;
> >
> > @@ -243,11 +236,8 @@ static int __cpufreq_stats_create_table(struct cpufreq_policy *policy,
> >          stat->last_time = get_jiffies_64();
> >          stat->last_index = freq_table_get_index(stat, policy->cur);
> >          spin_unlock(&cpufreq_stats_lock);
> > -       cpufreq_cpu_put(current_policy);
> >          return 0;
> >   error_out:
> > -       cpufreq_cpu_put(current_policy);
> > -error_get_fail:
> >          kfree(stat);
> >          per_cpu(cpufreq_stats_table, cpu) = NULL;
> >          return ret;
>
> I was damn sure that this wasn't a waste of time. This was some meaningful
> code when I visited it earlier. And we absolutely required a new
> cpufreq_cpu_get()..
>
> Reason: Earlier tables were created for this notifier: CPUFREQ_NOTIFY and
> it used to come with another changed copy of 'policy' and so we were required
> to get the real copy of policy to get to the right kobj.
>
> But recently I have simplified stuff there and these tables are now added with
> CPUFREQ_CREATE_POLICY and so this replication isn't required anymore.

Agreed. I already knew it had a good reason. :) Just that it's not 
needed anymore.

> So, Acked-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>

Thanks.

> While you are at it please get this part into __cpufreq_stats_create_table()
> routine:
>
> table = cpufreq_frequency_get_table(cpu);
> if (!table)
>      return 0;
>
> As it is replicated at two places currently.

Doing it as a separate patch since it's technically unrelated to these 
changes.

-Saravana

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