Re: [PATCH 1/2] param: allow omitting set() methods for trulyread-only params

From: Dmitry Torokhov
Date: Wed Aug 11 2010 - 03:35:59 EST


On Aug 10, 2010, at 6:39 PM, "Rusty Russell" <rusty@xxxxxxxxxxxxxxx>
wrote:

> On Wed, 11 Aug 2010 04:28:44 am Dmitry Torokhov wrote:
>> Certain "parameters", such as acpica version and upcoming VMware
>> Balloon
>> version, are need to be purely read-only. They are exported as
>> parameters so that they are visible in sysfs even in cases when the
>> module is built directly into the kernel, but their values should be
>> immutable. Specifying S_IRUGO takes care of sysfs interface, but it
>> has no effect on kernel command line or modprobe configuration
>> files and
>> so these "parameters" attempt to omit set() method. Unfortunately
>> kernel expects set() to be always present and crashes if it is not
>> there, so let's add appropriate check.
>>
>> Signed-off-by: Dmitry Torokhov <dtor@xxxxxxxxxx>
>
> That almost makes sense, but not quite.
>
> Your followup patch uses this for version, but the version is already
> in /sys/module/vmware_balloon/version as is standard with modules, no?
>

That version attribute is not present if the driver is built-in, only
parameters are visible in both cases.

--
Dmitry

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