Re: [PATCH v2 2/5] sysctl: Add flags to support min/max range clamping

[Waiman Long]

On 02/28/2018 01:58 PM, Waiman Long wrote:
> On 02/28/2018 01:43 PM, Luis R. Rodriguez wrote:
>> On Wed, Feb 28, 2018 at 12:53:40PM -0500, Waiman Long wrote:
>>> On 02/27/2018 07:47 PM, Luis R. Rodriguez wrote:
>>>> On Tue, Feb 27, 2018 at 03:49:48PM -0500, Waiman Long wrote:
>>>>> When minimum/maximum values are specified for a sysctl parameter in
>>>>> the ctl_table structure with proc_dointvec_minmax() handler,
>>>> an
>>>>
>>>>> update
>>>>> to that parameter will fail with error if the given value is outside
>>>>> of the required range.
>>>>>
>>>>> There are use cases where it may be better to clamp the value of
>>>>> the sysctl parameter to the given range without failing the update,
>>>>> especially if the users are not aware of the actual range limits.
>>>> Makes me wonder if we should add something which does let one query
>>>> for the ranges. Then scripts can fetch that as well.
>>> That will actually be better than printing out the range in the dmesg
>>> log. However, I haven't figured out an easy way of doing that. If you
>>> have any suggestion, please let me know about it.
>> I think a macro that also adds yet another proc read-only entry with a postfix
>> "_range" with an internal handler which prints the range may suffice.
>>
>>   Luis
> I think that is a possible solution. Instead of adding a macro, I will
> add one more flag which does the magic when the ctl_table entry is being
> processed. I think that will be simpler from the user point of view.
>
> Cheers,
> Longman
>
This patch will take a bit more time to work on. So I am going to do it
as a separate patch on top of the current one later. I don't want to
delay the review of the current patch set.

Cheers,
Longman