Re: [PATCH v4 1/2] cpufreq: intel_pstate: Rearrange the storing of new EPP values

Francisco Jerez
2020-07-30T01:31:10Z

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"Rafael J. Wysocki" <rjw@rjwysocki.net> writes:

> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>
> Move the locking away from intel_pstate_set_energy_pref_index()
> into its only caller and drop the (now redundant) return_pref label
> from it.
>
> Also move the "raw" EPP value check into the caller of that function,
> so as to do it before acquiring the mutex, and reduce code duplication
> related to the "raw" EPP values processing somewhat.
>
> No intentional functional impact.
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Reviewed-by: Francisco Jerez <currojerez@riseup.net>

> ---
>
> v2 -> v3:
>
> * Fix error handling in intel_pstate_set_energy_pref_index() and
> rebase.
>
> v3 -> v4: No changes
>
> ---
> drivers/cpufreq/intel_pstate.c | 35 +++++++++++++++--------------------
> 1 file changed, 15 insertions(+), 20 deletions(-)
>
> Index: linux-pm/drivers/cpufreq/intel_pstate.c
> ===================================================================
> --- linux-pm.orig/drivers/cpufreq/intel_pstate.c
> +++ linux-pm/drivers/cpufreq/intel_pstate.c
> @@ -649,28 +649,18 @@ static int intel_pstate_set_energy_pref_
> if (!pref_index)
> epp = cpu_data->epp_default;
>
> - mutex_lock(&intel_pstate_limits_lock);
> -
> if (boot_cpu_has(X86_FEATURE_HWP_EPP)) {
> u64 value;
>
> ret = rdmsrl_on_cpu(cpu_data->cpu, MSR_HWP_REQUEST, &value);
> if (ret)
> - goto return_pref;
> + return ret;
>
> value &= ~GENMASK_ULL(31, 24);
>
> - if (use_raw) {
> - if (raw_epp > 255) {
> - ret = -EINVAL;
> - goto return_pref;
> - }
> - value |= (u64)raw_epp << 24;
> - ret = wrmsrl_on_cpu(cpu_data->cpu, MSR_HWP_REQUEST, value);
> - goto return_pref;
> - }
> -
> - if (epp == -EINVAL)
> + if (use_raw)
> + epp = raw_epp;
> + else if (epp == -EINVAL)
> epp = epp_values[pref_index - 1];
>
> value |= (u64)epp << 24;
> @@ -680,8 +670,6 @@ static int intel_pstate_set_energy_pref_
> epp = (pref_index - 1) << 2;
> ret = intel_pstate_set_epb(cpu_data->cpu, epp);
> }
> -return_pref:
> - mutex_unlock(&intel_pstate_limits_lock);
>
> return ret;
> }
> @@ -708,8 +696,8 @@ static ssize_t store_energy_performance_
> struct cpudata *cpu_data = all_cpu_data[policy->cpu];
> char str_preference[21];
> bool raw = false;
> + ssize_t ret;
> u32 epp = 0;
> - int ret;
>
> ret = sscanf(buf, "%20s", str_preference);
> if (ret != 1)
> @@ -724,14 +712,21 @@ static ssize_t store_energy_performance_
> if (ret)
> return ret;
>
> + if (epp > 255)
> + return -EINVAL;
> +
> raw = true;
> }
>
> + mutex_lock(&intel_pstate_limits_lock);
> +
> ret = intel_pstate_set_energy_pref_index(cpu_data, ret, raw, epp);
> - if (ret)
> - return ret;
> + if (!ret)
> + ret = count;
>
> - return count;
> + mutex_unlock(&intel_pstate_limits_lock);
> +
> + return ret;
> }
>
> static ssize_t show_energy_performance_preference(

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