linux-kernel - Re: klp: remove superfluous errors in asm/livepatch.h

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Message-ID: <20160308212819.GA9075@packer-debian-8-amd64.digitalocean.com>
Date:	Tue, 8 Mar 2016 16:28:20 -0500
From:	Jessica Yu <jeyu@...hat.com>
To:	Jiri Kosina <jikos@...nel.org>
Cc:	Josh Poimboeuf <jpoimboe@...hat.com>,
	Miroslav Benes <mbenes@...e.cz>, sjenning@...hat.com,
	vojtech@...e.com, pmladek@...e.cz, mpe@...erman.id.au,
	live-patching@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: klp: remove superfluous errors in asm/livepatch.h

+++ Jiri Kosina [06/03/16 22:13 +0100]:
>On Fri, 4 Mar 2016, Josh Poimboeuf wrote:
>
>> > There is an #error in asm/livepatch.h for both x86 and s390 in
>> > !CONFIG_LIVEPATCH cases. It does not make much sense as pointed out by
>> > Michael Ellerman. One can happily include asm/livepatch.h with
>> > CONFIG_LIVEPATCH. Remove it as useless.
>> >
>> > Suggested-by: Michael Ellerman <mpe@...erman.id.au>
>> > Signed-off-by: Miroslav Benes <mbenes@...e.cz>
>>
>> Looks fine to me.
>
>Thanks. I consider this to be your Ack then :) (if you disagree, please
>shout loudly).
>
>> While we're at it, do we even need the '#ifdef CONFIG_LIVEPATCH' in
>> these files?  And in include/linux/livepatch.h?
>
>You are right, this seems indeed completely unnecessary. I'll remove it
>for 4.6 as well, if noone has any objections.

Hm, I should've caught this earlier, but the notifier cleanup patch
that removes the livepatch module notifier had kernel/module.c include
livepatch.h for the klp_module_{coming,going} function stubs in the
!CONFIG_LIVEPATCH case. See here: https://lkml.org/lkml/2016/2/8/1182

Looking back, I now don't think it makes sense for module.c to include
all those livepatch definitions in the first place, since all it
needed was the klp_module_{coming,going} declarations. I guess my
question is, since we've removed the #ifdef CONFIG_LIVEPATCH blocks
from livepatch.h, where might be a better place for the
klp_module_{coming,going} stubs? Perhaps they could go in module.h
instead?

Jessica