Re: [PATCH v1] iio: trigger: warn about non-registered iio trigger getting attempt

["Nuno Sá" <noname.nuno@gmail.com>]

On Wed, 2022-06-01 at 10:33 +0000, Dmitry Rokosov wrote:
> Hi Nuno,
> 
> Thank you for comments!
> 
> On Wed, Jun 01, 2022 at 10:47:54AM +0200, Nuno Sá wrote:
> > On Tue, 2022-05-31 at 18:57 +0000, Dmitry Rokosov wrote:
> > > Hi Jonathan,
> > > 
> > > I have one question about a cases when trigger owner is builtin
> > > module.
> > > In the such cases trig->owner == null, because THIS_MODULE equals
> > > to
> > > null. How do you think, should we take into account such
> > > situations?
> > > 
> > > IMHO we have to take in and save this information to trig_info
> > > during
> > > trigger allocation call. For example we can check THIS_MODULE
> > > from
> > > the
> > 
> > Hmmm, If we were to do something during iio_trigger_alloc(), we
> > would
> > rather assign already THIS_MODULE to owner and we would not need
> > this
> > WARN(). I mean, if someone calls iio_trigger_get() before
> > allocating
> > it, it will have bigger problems :).
> > 
> 
> You are right, non-allocated pointer dereference is much bigger
> problem :)
> 
> > I think this could actually be something reasonable...
> 
> I think it could be a good solution, but it's required a lot of
> changes
> in the IIO drivers code, because if we assign trig->owner from
> iio_trigger_alloc(), we do not need this_mod parameter in the
> iio_trigger_register() iface and its wrappers.
> So it means to make it workable we must:
>     - rework iio_trigger_alloc()
>     - redesign iio_trigger_register() iface and its wrappers
>     - correct iio_trigger_register() call from all IIO drivers
> 
> I suppose we need to wait for Jonathan's comments here...
> 

I think we could actually get this done without having to change all
the drivers. Note on how iio_trigger_register() passes THIS_MODULE to
the internal API. We could also use macros in the alloc function in a
way that only internal functions would need to be changed. But it all
depends on whether or not Jonathan wants this moved...

- Nuno Sá