Re: [PATCH 11/15] static_call: Add inline static call infrastructure

[Josh Poimboeuf]

On Fri, Jun 07, 2019 at 10:37:56AM +0200, Peter Zijlstra wrote:
> > > +}
> > > +
> > > +static int static_call_module_notify(struct notifier_block *nb,
> > > +				     unsigned long val, void *data)
> > > +{
> > > +	struct module *mod = data;
> > > +	int ret = 0;
> > > +
> > > +	cpus_read_lock();
> > > +	static_call_lock();
> > > +
> > > +	switch (val) {
> > > +	case MODULE_STATE_COMING:
> > > +		module_disable_ro(mod);
> > > +		ret = static_call_add_module(mod);
> > > +		module_enable_ro(mod, false);
> > 
> > Doesnât it cause some pages to be W+X ?

How so?

>> Can it be avoided?
> 
> I don't know why it does this, jump_labels doesn't seem to need this,
> and I'm not seeing what static_call needs differently.

I forgot why I did this, but it's probably for the case where there's a
static call site in module init code.  It deserves a comment.

Theoretically, jump labels need this to.

BTW, there's a change coming that will require the text_mutex before
calling module_{disable,enable}_ro().

-- 
Josh