Em Thu, 5 May 2022 23:35:29 +0200
Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx> escreveu:
> Hi Mauro,
>
> [...]
>
> > +static int ref_module_dependency(struct module *mod, struct module *this)
> > +{
> > + int ret;
> > +
> > + if (!this || !this->name)
> > + return -EINVAL;
> > +
> > + if (mod == this)
> > + return 0;
> > +
> > + mutex_lock(&module_mutex);
> > +
> > + ret = ref_module(this, mod);
> > +
> > +#ifdef CONFIG_MODULE_UNLOAD
> > + if (ret)
> > + goto ret;
> > +
> > + ret = sysfs_create_link(mod->holders_dir,
> > + &this->mkobj.kobj, this->name);
> > +#endif
> > +
> > +ret:
> > + mutex_unlock(&module_mutex);
> > + return ret;
> > +}
> > +
> > /* Clear the unload stuff of the module. */
> > static void module_unload_free(struct module *mod)
> > {
> > @@ -841,24 +886,16 @@ void __module_get(struct module *module)
> > }
> > EXPORT_SYMBOL(__module_get);
> >
> > -bool try_module_get(struct module *module)
> > +bool try_module_get_owner(struct module *module, struct module *this)
> > {
> > - bool ret = true;
> > + int ret = __try_module_get(module);
> >
> > - if (module) {
> > - preempt_disable();
> > - /* Note: here, we can fail to get a reference */
> > - if (likely(module_is_live(module) &&
> > - atomic_inc_not_zero(&module->refcnt) != 0))
> > - trace_module_get(module, _RET_IP_);
> > - else
> > - ret = false;
> > + if (ret)
> > + ref_module_dependency(module, this);
>
> do we care about the return value here?
I don't think it should care about the return value, as a failure to
create a sysfs node for the holder or to add it to the holders list
is not fatal: modules can still continue working without that.
Also, I opted to be conservative here: currently, not creating these
doesn't cause try_module_get() to fail. I'm not sure what would be the
impact if this starts to fail.
So, right now, I'm opting to just ignore the return value. Perhaps
in the future this could a warning (similarly to what sysfs create
link does).
Regards,
Mauro
>
> Andi
>
> >
> > - preempt_enable();
> > - }
> > return ret;
> > }
> > -EXPORT_SYMBOL(try_module_get);
> > +EXPORT_SYMBOL(try_module_get_owner);
> >
> > void module_put(struct module *module)
> > {
> > --
> > 2.35.1
Thanks,
Mauro
