linux-kernel - Re: [PATCH 3/3] module: Improve module __ro_after

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Date:   Fri, 14 Jun 2019 13:23:41 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Petr Mladek <pmladek@...e.com>
Cc:     Jessica Yu <jeyu@...nel.org>, Steven Rostedt <rostedt@...dmis.org>,
        Jiri Kosina <jikos@...nel.org>,
        Miroslav Benes <mbenes@...e.cz>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        linux-kernel@...r.kernel.org, live-patching@...r.kernel.org,
        Johannes Erdfelt <johannes@...felt.com>,
        Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH 3/3] module: Improve module __ro_after_init handling

On Fri, Jun 14, 2019 at 04:14:53PM +0200, Petr Mladek wrote:
> > -void __module_enable_ro(const struct module *mod, bool after_init)
> > +static void __module_enable_ro(const struct module *mod)
> >  {
> >  	if (!rodata_enabled)
> >  		return;
> > @@ -1973,15 +1973,15 @@ void __module_enable_ro(const struct module *mod, bool after_init)
> >  
> >  	frob_rodata(&mod->init_layout, set_memory_ro);
> >  
> > -	if (after_init)
> > +	if (mod->state == MODULE_STATE_LIVE)
> >  		frob_ro_after_init(&mod->core_layout, set_memory_ro);
> 
> This works only now because __module_enable_ro() is called only from
> three locations (klp_init_object_loaded(),  complete_formation(),
> and do_init_module(). And they all are called in a well defined order
> from load_module().
> 
> Only the final call in do_init_module() should touch the after_init
> section.
> 
> IMHO, the most clean solutiuon would be to call frob_ro_after_init()
> from extra __module_after_init_enable_ro() or so. This should be
> called only from the single place.

Agreed, that would be better.  I'll be gone for a week but I'll make
these changes when I get back.  Thanks.

-- 
Josh