Re: [PATCH 2/2] e_powersaver: Require setting a module parameter to enable it

On 9 June 2014 04:52, Ben Hutchings <[email protected]> wrote:
> The Kconfig text and comment at the top of the file say this is
> DANGEROUS.  According to Rafał Bilski it is not so bad as it used to
> be, but he still didn't think it should be auto-loaded.
>
> Rafał already made a similar change to longhaul.
>
> References: http://www.spinics.net/lists/cpufreq/msg02919.html
> Signed-off-by: Ben Hutchings <[email protected]>
> ---
>  drivers/cpufreq/e_powersaver.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
>
> diff --git a/drivers/cpufreq/e_powersaver.c b/drivers/cpufreq/e_powersaver.c
> index a0d2a42..880be39 100644
> --- a/drivers/cpufreq/e_powersaver.c
> +++ b/drivers/cpufreq/e_powersaver.c
> @@ -45,6 +45,7 @@ static struct eps_cpu_data *eps_cpu[NR_CPUS];
>  static int freq_failsafe_off;
>  static int voltage_failsafe_off;
>  static int set_max_voltage;
> +static int enable;
>
>  #if defined CONFIG_ACPI_PROCESSOR || defined CONFIG_ACPI_PROCESSOR_MODULE
>  static int ignore_acpi_limit;
> @@ -410,6 +411,10 @@ static int __init eps_init(void)
>  {
>         if (!x86_match_cpu(eps_cpu_id) || boot_cpu_data.x86_model < 10)
>                 return -ENODEV;
> +       if (!enable) {
> +               printk(KERN_ERR "eps: Option \"enable\" not set. Aborting.\n");
> +               return -ENODEV;
> +       }
>         if (cpufreq_register_driver(&eps_driver))
>                 return -EINVAL;
>         return 0;
> @@ -432,6 +437,10 @@ MODULE_PARM_DESC(ignore_acpi_limit, "Don't check ACPI's processor speed limit");
>  #endif
>  module_param(set_max_voltage, int, 0644);
>  MODULE_PARM_DESC(set_max_voltage, "Set maximum CPU voltage (mV) C7-M only");
> +/* By default driver is disabled to prevent incompatible
> + * system freeze. */

This could have been written with proper style mentioned in CodingGuidelines

> +module_param(enable, int, 0644);
> +MODULE_PARM_DESC(enable, "Enable driver");
>
>  MODULE_AUTHOR("Rafal Bilski <[email protected]>");
>  MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's.");

Acked-by: Viresh Kumar <[email protected]>