Re: [PATCH 1/4] container_of: add container_of_const() that preserves const-ness of the pointer

From: Andy Shevchenko
Date: Fri Dec 02 2022 - 07:01:44 EST


On Fri, Dec 02, 2022 at 11:45:55AM +0100, Greg Kroah-Hartman wrote:
> On Thu, Dec 01, 2022 at 11:21:50PM +0000, Sakari Ailus wrote:
> > On Thu, Dec 01, 2022 at 08:30:54PM +0100, Greg Kroah-Hartman wrote:
> > > container_of does not preserve the const-ness of a pointer that is
> > > passed into it, which can cause C code that passes in a const pointer to
> > > get a pointer back that is not const and then scribble all over the data
> > > in it. To prevent this, container_of_const() will preserve the const
> > > status of the pointer passed into it using the newly available _Generic()
> > > method.
> >
> > "_const" in the name suggests that the macro would always take a const
> > argument.
>
> I mean it here to be "this will preserve const" as yes, it can take a
> const. Or not.
>
> > Could this be called e.g. container_of_safe() (for type-safe, but
> > full type_safe would be a bit long)?
>
> const is an attribute of type safety, container_of is also type-safe
> as-is, it's just the const portion here that is the difference between
> the two.

container_of_const_safe() :-)

> Naming is hard :(

True.

--
With Best Regards,
Andy Shevchenko