Re: [PATCH] sysctl: Allow /proc/sys without sys_sysctl

[ebiederm@xmission.com (Eric W. Biederman)]

Andi Kleen <ak@suse.de> writes:

> ebiederm@xmission.com (Eric W. Biederman) writes:
>
>> Since sys_sysctl is deprecated start allow it to be compiled out.
>> This should catch any remaining user space code that cares,
>
> I tried this long ago, but found that glibc uses sysctl in each
> program to get the kernel version. It probably handles ENOSYS,
> but there might be slowdowns or subtle problems from it not knowing
> the kernel version.
>
> So I think it's ok to remove the big sysctl, but at a very minimal
> replacement that just handles (CTL_KERN, KERN_VERSION) is needed.

If glibc is looking at kernel.osrelease it might make sense.
If glibc is looking at kernel.version which is just the build number
and date I can't imagine a correct usage.

If this usage is still common in glibc we can decide what to do
when the warnings pop up.

> Also it's useful to printk for the rest at least for some time 
> so we know what uses it.

Yes.  Andrew and I discussed that and when he picked up a patch.
A printk was added to warn of people using the interface.

Eric