linux-kernel - Re: [PATCH 4/8] livepatch: Add an extra flag to distinguish registered patches

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Date:   Tue, 10 Apr 2018 12:53:34 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Miroslav Benes <mbenes@...e.cz>, Jiri Kosina <jikos@...nel.org>,
        Jason Baron <jbaron@...mai.com>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Jessica Yu <jeyu@...nel.org>,
        Evgenii Shatokhin <eshatokhin@...tuozzo.com>,
        live-patching@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/8] livepatch: Add an extra flag to distinguish
 registered patches

On Tue, Apr 10, 2018 at 12:56:25PM +0200, Petr Mladek wrote:
> > > diff --git a/include/linux/livepatch.h b/include/linux/livepatch.h
> > > index f28af280f9e0..d6e6d8176995 100644
> > > --- a/include/linux/livepatch.h
> > > +++ b/include/linux/livepatch.h
> > > @@ -378,7 +383,7 @@ int klp_disable_patch(struct klp_patch *patch)
> > >  
> > >  	mutex_lock(&klp_mutex);
> > >  
> > > -	if (!klp_is_patch_registered(patch)) {
> > > +	if (!patch->registered) {
> > 
> > I don't see any actual problem, but I'd feel safer if we preserve 
> > klp_is_patch_on_stack() even somewhere in disable path.
> 
> It is strictly needed in klp_enable_patch() which will be better
> visible if I squash it with the next patch.
> 
> The use in klp_disable_patch() is optional. I do not have problems
> to add it there though. If Josh does not see it as too paranoid,
> I'll add it.

That does seem pointless to me, how did you know? :-)

Of course if we make the other changes we've been discussing, maybe it's
no longer an issue.

-- 
Josh