[Devel] Re: [PATCH 5/9] cr: capabilities: define checkpoint and restore fns

[Andrew G. Morgan]

On Mon, Jun 1, 2009 at 3:18 PM, Serge E. Hallyn <serue at us.ibm.com> wrote:
> Quoting Andrew G. Morgan (morgan at kernel.org):
>> On Mon, Jun 1, 2009 at 6:35 AM, Serge E. Hallyn <serue at us.ibm.com> wrote:
>> >> > I'll put in a commented BUILD_BUG_ON like Alexey suggests - does that
>> >> > suffice?
>>
>> I can't speak for other subsystems, but it seems to me as if for the
>> capabilities, I'd want to create something like this in
>> include/linux/capabilities.h
>>
>> typedef struct checkpoint_caps_s {
>>    /* what goes in here is the capability code's business */
>> } checkpoint_caps_t;
>
> Sigh - Did a patch this way, but the problem is userspace needs to be
> able to parse the checkpoint image, so it needs to know what this struct
> looks like.  So if I put it the struct definition
> include/linux/capability.h, I run into a whole new set of problems
> trying to compile a userspace program to do a sys_restart().

Does the user space app need to be able to modify the data in some
way? It seems like embedding a length with the structure or something
might simplify such a user space dependency.

> So I went part-way to what you suggested in the patchset I'm about to
> send out (please see patch 6/8).  I think the caps code does look
> nicer in this new version.

Better, but I remain concerned that the code looks hard to maintain
when structured this way.

Cheers

Andrew
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