Messages in this thread | | | Date | Thu, 18 Jul 2002 12:01:09 +0200 (CEST) | From | Roman Zippel <> | Subject | Re: [RFC] new module format |
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Hi,
On Thu, 18 Jul 2002, Daniel Phillips wrote:
> But I don't see why this needs to be a two step process: > > module support calls mod->cleanup > module code checks number of users > if none, unregister all interfaces > otherwise return -EBUSY > if return wasn't -EBUSY, free all resources
So after you checked for users, someone starts using the module again, before you were able to remove all interfaces -> OOPS. This is exactly the reason why I prefer to make this explicit in the module interface - the chances are higher to get this right.
> > It's possible to use the filesystem model, but it's unnecessary complex > > and inflexible. > > What is the complex and inflexible part?
It has to work around the problem that cleanup_module() can't fail.
> > Another problem is that the more interfaces a module has (e.g. proc), the > > harder it becomes to unload a module (or the easier it becomes to prevent > > the unloading of a module). > > I don't see that this makes any difference at all.
It's currently impossible to force the unloading of a module, some user can always keep a reference to the module. Even if you kill the process, someone else can get a new reference, before you could unload the module.
> I'm proposing to add a return code to mod->cleanup (and pick a better > name). Yes, every module will have to be fixed to use this interface, but > why not?
I don't disagree, but if we break the module interface anyway, why don't we clean it up properly? (Patches that do that will follow shortly.)
> Anyway, you're proposing to do it backwards. We need to first ensure > there are no users, then unregister the interfaces.
That's broken (see above).
bye, Roman
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