barriers: was: [RFC PATCH v2 17/18] livepatch: change to a per-task consistency model

Josh Poimboeuf jpoimboe at
Thu May 5 03:02:36 AEST 2016

On Wed, May 04, 2016 at 02:39:40PM +0200, Petr Mladek wrote:
> On Thu 2016-04-28 15:44:48, Josh Poimboeuf wrote:
> > Change livepatch to use a basic per-task consistency model.  This is the
> > foundation which will eventually enable us to patch those ~10% of
> > security patches which change function or data semantics.  This is the
> > biggest remaining piece needed to make livepatch more generally useful.
> I spent a lot of time with checking the memory barriers. It seems that
> they are basically correct.  Let me use my own words to show how
> I understand it. I hope that it will help others with review.

[...snip a ton of useful comments...]

Thanks, this will help a lot!  I'll try to incorporate your barrier
comments into the code.

I also agree that kpatch_patch_task() is poorly named.  I was trying to
make it clear to external callers that "hey, the task is getting patched
now!", but it's internally inconsistent with livepatch code because we
make a distinction between patching and unpatching.

Maybe I'll do:



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