Hi Javier,
On Sat, Apr 22, 2023 at 07:26:13AM +0200, Javier Martinez Canillas wrote:
> Maxime Ripard <maxime@xxxxxxxxxx> writes:
> > container_of_const() allows to preserve the pointer constness and is
> > thus more flexible than inline functions.
> >
> > Let's switch all our instances of container_of() to
> > container_of_const().
> >
> > Signed-off-by: Maxime Ripard <maxime@xxxxxxxxxx>
> > ---
>
> [...]
>
> > -static inline struct vc4_dpi *
> > -to_vc4_dpi(struct drm_encoder *encoder)
> > -{
> > - return container_of(encoder, struct vc4_dpi, encoder.base);
> > -}
> > +#define to_vc4_dpi(_encoder) \
> > + container_of_const(_encoder, struct vc4_dpi, encoder.base)
> >
>
> A disadvantage of this approach though is that the type checking is lost.
Not entirely, the argument is still type-checked, but yeah, it's true
for the returned value.
> Since you already had these, I would probably had changed them to return
> a const pointer and just replace container_of() for container_of_const().
>
> But I see that there are a lot of patches from Greg all over the kernel
> that do exactly this, dropping static inline functions in favor of using
> container_of_const() directly. So it seems the convention is what you do.
More importantly, container_of_const() isn't always returning a const
pointer or always taking a const argument, it's returning the pointer
with the same const-ness than the argument.
This is why it makes sense to remove the inline function entirely,
because it removes the main benefit it brings.
> Reviewed-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
Thanks, I've applied this series
Maxime
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