Re: [RFC 0/5] livepatch: new API to track system state changes

On Tue, Jun 11, 2019 at 03:56:22PM +0200, Petr Mladek wrote:

Hi,

this is another piece in the puzzle that helps to maintain more
livepatches.

Especially pre/post (un)patch callbacks might change a system state.
Any newly installed livepatch has to somehow deal with system state
modifications done be already installed livepatches.

This patchset provides, hopefully, a simple and generic API that
helps to keep and pass information between the livepatches.
It is also usable to prevent loading incompatible livepatches.

Thanks for posting, Petr and aplogies for not getting to this RFC
earlier.  I think this strikes a reasonable balance between the (too) 
"simplified" versioning scheme that I posted a few weeks back, and what
I was afraid might have been too complicated callback-state-version
concept.

This RFC reads fairly straightforward and especially easy to review
given the included documentation and self-tests.  I'll add a few
comments per patch, but again, I like how this came out.
 

There was also a related idea to add a sticky flag. It should be
easy to add it later. It would perfectly fit into the new struct
klp_state.

I think so, too.  It would indicate that the patch is introducing a
state which cannot be safely unloaded.  But we can talk about that at a
later time if/when we want to add that wrinkle to klp_state.
 
-- Joe