linux-kernel - Re: livepatch: Implement separate coming and going module notifiers

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Message-ID: <20160129151028.11d26779@gandalf.local.home>
Date:	Fri, 29 Jan 2016 15:10:28 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Jessica Yu <jeyu@...hat.com>
Cc:	Josh Poimboeuf <jpoimboe@...hat.com>,
	Miroslav Benes <mbenes@...e.cz>,
	Seth Jennings <sjenning@...hat.com>,
	Jiri Kosina <jikos@...nel.org>,
	Vojtech Pavlik <vojtech@...e.com>,
	Ingo Molnar <mingo@...hat.com>, live-patching@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: livepatch: Implement separate coming and going module notifiers

On Fri, 29 Jan 2016 15:09:31 -0500
Steven Rostedt <rostedt@...dmis.org> wrote:

> On Fri, 29 Jan 2016 15:04:51 -0500
> Jessica Yu <jeyu@...hat.com> wrote:
> 
> > >diff --git a/kernel/module.c b/kernel/module.c
> > >index 8358f46..aeabd81 100644
> > >--- a/kernel/module.c
> > >+++ b/kernel/module.c
> > >@@ -3371,6 +3371,13 @@ static int complete_formation(struct module *mod, struct load_info *info)
> > > 	mod->state = MODULE_STATE_COMING;
> > > 	mutex_unlock(&module_mutex);
> > >
> > >+	ftrace_module_enable(mod);
> > >+	err = klp_module_enable(mod);
> > >+	if (err) {
> > >+		ftrace_release_mod(mod);
> > >+		return err;
> > >+	}    
> > 
> > If we go this route, should we should print a big warning ("Livepatch
> > couldn't patch loading module X") instead of aborting the module load
> > completely?   
> 
> If anything, that should be done in klp_module_enable() not in the
> module code.

And I take that back. The module wont load. The user will notice that
before any console warning. Thus no warning needed.

-- Steve