Re: [PATCH RFC 1/4] kmod: add a routine to return if usermode is disabled

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Jun 26, 2012 at 04:34:19PM -0300, Mauro Carvalho Chehab wrote:
> Several media devices are only capable of probing the device if
> the firmware load is enabled, e. g. when the usermode var is not
> disabled.
> 
> Add a routine to allow those drivers to test if probe can continue
> or need to be deferred.
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
> ---
>  include/linux/firmware.h |    6 ++++++
>  kernel/kmod.c            |    6 ++++++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/include/linux/firmware.h b/include/linux/firmware.h
> index 1e7c011..cacf27e 100644
> --- a/include/linux/firmware.h
> +++ b/include/linux/firmware.h
> @@ -35,6 +35,12 @@ struct builtin_fw {
>  	static const struct builtin_fw __fw_concat(__builtin_fw,__COUNTER__) \
>  	__used __section(.builtin_fw) = { name, blob, size }
>  
> +/**
> + * is_usermodehelp_disabled - returns true if firmware usermode is disabled
> + *			      false otherwise.
> + */
> +bool is_usermodehelp_disabled(void);
> +
>  #if defined(CONFIG_FW_LOADER) || (defined(CONFIG_FW_LOADER_MODULE) && defined(MODULE))
>  int request_firmware(const struct firmware **fw, const char *name,
>  		     struct device *device);
> diff --git a/kernel/kmod.c b/kernel/kmod.c
> index 05698a7..68901308 100644
> --- a/kernel/kmod.c
> +++ b/kernel/kmod.c
> @@ -339,6 +339,12 @@ static DECLARE_WAIT_QUEUE_HEAD(running_helpers_waitq);
>   */
>  static DECLARE_WAIT_QUEUE_HEAD(usermodehelper_disabled_waitq);
>  
> +bool is_usermodehelp_disabled(void)
> +{
> +	return usermodehelper_disabled ? true : false;
> +}
> +EXPORT_SYMBOL_GPL(is_usermodehelp_disabled);

usermodehelper_disabled is an enum, and the 0 value is UMH_ENABLED, so I
think you need to explicitly test for the correct value here, you don't
want to return something incorrectly for UMH_FREEZING, right?

greg k-h