Re: [PATCH v4 1/2] driver core: Introduce device_link_wait_removal()

[Herve Codina <herve.codina@bootlin.com>]

Hi Nuno,

On Wed, 06 Mar 2024 15:50:44 +0100
Nuno Sá <noname.nuno@gmail.com> wrote:

...
> > > > > 
> > > > > That makes sense but then the only thing I still don't fully get is why
> > > > > we
> > > > > have
> > > > > a separate devlink_class_init() initcall for registering the devlink
> > > > > class
> > > > > (which can also fail)...  
> > > > 
> > > > Well, I haven't added it. :-)
> > > >   
> > > > > What I take from the above is that we should fail the
> > > > > driver model if one of it's fundamental components fails so I would say
> > > > > we
> > > > > should merge devlink_class_init() with device_init() otherwise it's a
> > > > > bit
> > > > > confusing (at least to me) and gives the idea that it's ok for the
> > > > > driver
> > > > > model
> > > > > to exist without the links (unless I'm missing some other reason for the
> > > > > devlink
> > > > > init function).  
> > > > 
> > > > +1
> > > > 
> > > > Feel free to send a patch along these lines, chances are that it will
> > > > be popular. ;-)  
> > > 
> > > I was actually thinking about that but I think I encountered the reason why
> > > we
> > > have it like this... devices_init() is called from driver_init() and there
> > > we
> > > have:
> > > 
> > > ...
> > > 
> > > devices_init();
> > > buses_init();
> > > classes_init();
> > > 
> > > ...
> > > 
> > > So classes are initialized after devices which means we can't really do
> > > class_register(&devlink_class) from devices_init(). Unless, of course, we
> > > re-
> > > order things in driver_init() but that would be a questionable change at the
> > > very least.
> > > 
> > > So, while I agree with what you've said, I'm still not sure if mixing
> > > devlink
> > > stuff between devices_init() and devlink_class_init() is the best thing to
> > > do
> > > given that we already have the case where devlink_class_init() can fail
> > > while
> > > the driver model is up.  
> > 
> > So why don't you make devlink_class_init() do a BUG() on failure
> > instead of returning an error?  IMO crashing early is better than
> > crashing later or otherwise failing in a subtle way due to a missed
> > dependency.  
> 
> Well, I do agree with that... Maybe that's something that Herve can sneak in
> this patch? Otherwise, I can later (after this one is applied) send a patch for
> it.

Well, I don't thing that this have to be part of this current series.
It is an other topic and should be handled out of this current series.

Hervé