Re: [PATCH] module: check for exit sections in layout_sections() instead of module_init_section()

[Jessica Yu]

+++ Russell King - ARM Linux admin [12/05/21 17:06 +0100]:
> Hi,
>
> On Wed, May 12, 2021 at 04:46:53PM +0200, Jessica Yu wrote:
> > diff --git a/kernel/module.c b/kernel/module.c
> > index 173a09175511..a5c9842371b1 100644
> > --- a/kernel/module.c
> > +++ b/kernel/module.c
> > @@ -2430,6 +2430,9 @@ static void layout_sections(struct module *mod, struct load_info *info)
> >  			if ((s->sh_flags & masks[m][0]) != masks[m][0]
> >  			    || (s->sh_flags & masks[m][1])
> >  			    || s->sh_entsize != ~0UL
> > +#ifndef CONFIG_MODULE_UNLOAD
> > +			    || module_exit_section(sname)
> > +#endif
> >  			    || module_init_section(sname))
>
> How about a helper to make this a bit easier in both these places to
> make the code more undertsandable? I think the great value comes from
> the resulting change in the second hunk.
>
> static bool module_evictable_section(const char *sname)
> {
> #ifndef CONFIG_MODULE_UNLOAD
> 	if (module_exit_section(sname))
> 		return true;
> #endif
> 	return module_init_section(sname);
> }
>
> and then just use that above?
>
> >  				continue;
> >  			s->sh_entsize = get_offset(mod, &mod->core_layout.size, s, i);
> > @@ -2463,7 +2466,11 @@ static void layout_sections(struct module *mod, struct load_info *info)
> >  			if ((s->sh_flags & masks[m][0]) != masks[m][0]
> >  			    || (s->sh_flags & masks[m][1])
> >  			    || s->sh_entsize != ~0UL
> > +#ifndef CONFIG_MODULE_UNLOAD
> > +			    || (!module_init_section(sname) && !module_exit_section(sname)))
> > +#else
> >  			    || !module_init_section(sname))
> > +#endif
>
> I find this a tad confusing, and this is the reason for my suggestion
> above. With that, this becomes:
>
> 			    || !module_evictable_section(sname))
>
> which can be clearly seen is the opposite condition from the above
> without doing mental logic gymnastics.

Thanks Russell for the feedback! Yeah, agreed that it could be made
easier to read - will respin with a helper function.

Jessica