From: Amit Kucheria <amitk@kernel.org>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Rafael Wysocki <rjw@rjwysocki.net>,
Andy Gross <agross@kernel.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Linux PM list <linux-pm@vger.kernel.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
ionela.voinescu@arm.com,
linux-arm-msm <linux-arm-msm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] cpufreq: cached_resolved_idx can not be negative
Date: Thu, 30 Jul 2020 12:02:27 +0530 [thread overview]
Message-ID: <CAHLCerMD_spZFHER-y9dOzr7qo9xKXZdqy3cFt+W9QUW4Ng3jw@mail.gmail.com> (raw)
In-Reply-To: <20200730061041.gyprgwfkzfb64t3m@vireshk-mac-ubuntu>
On Thu, Jul 30, 2020 at 11:40 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> On 30-07-20, 11:29, Amit Kucheria wrote:
> > On Thu, Jul 30, 2020 at 9:38 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
> > >
> > > It is not possible for cached_resolved_idx to be invalid here as the
> > > cpufreq core always sets index to a positive value.
> > >
> > > Change its type to unsigned int and fix qcom usage a bit.
> >
> > Shouldn't you fix up idx in cpufreq_driver_resolve_freq() to be
> > unsigned int too?
>
> Yes, merged this into the patch.
Looking at this more closely, I found another call site for
cpufreq_frequency_table_target() in cpufreq.c that needs the index to
be unsigned int.
But then cpufreq_frequency_table_target() returns -EINVAL, so we
should be able to handle int values.
I think you will need to fix the unconditional assignment of
policy->cached_resolved_idx = idx
in cpufreq_driver_resolve_freq(). It doesn't check for -EINVAL, so the
qcom driver is write in checking for a negative value.
>
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index 0128de3603df..053d72e52a31 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -538,7 +538,7 @@ unsigned int cpufreq_driver_resolve_freq(struct cpufreq_policy *policy,
> policy->cached_target_freq = target_freq;
>
> if (cpufreq_driver->target_index) {
> - int idx;
> + unsigned int idx;
>
> idx = cpufreq_frequency_table_target(policy, target_freq,
> CPUFREQ_RELATION_L);
>
> --
> viresh
next prev parent reply other threads:[~2020-07-30 6:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-30 4:08 [PATCH] cpufreq: cached_resolved_idx can not be negative Viresh Kumar
2020-07-30 5:59 ` Amit Kucheria
2020-07-30 6:10 ` Viresh Kumar
2020-07-30 6:32 ` Amit Kucheria [this message]
2020-07-30 6:41 ` Viresh Kumar
2020-07-30 16:25 ` Rafael J. Wysocki
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