linux-kernel - Re: [PATCH v2 1/5] device property: Keep dev_fwnode() and dev_fwnode

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Date:   Mon, 3 Oct 2022 12:00:57 +0000
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Prashant Malani <pmalani@...omium.org>,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, Daniel Scally <djrscally@...il.com>
Subject: Re: [PATCH v2 1/5] device property: Keep dev_fwnode() and
 dev_fwnode_const() separate

Hi Rafael,

On Mon, Oct 03, 2022 at 01:54:37PM +0200, Rafael J. Wysocki wrote:
> > I ask as I just went through a large refactoring of the kobject layer to
> > mark many things const * and I find it a bit "sad" that functions like
> > this:
> >         static inline struct device *kobj_to_dev(const struct kobject *kobj)
> >         {
> >                 return container_of(kobj, struct device, kobj);
> >         }
> > have the ability to take a read-only pointer and spit out a writable one
> > thanks to the pointer math in container_of() with no one being the
> > wiser.
> 
> Well, is this really a problem?
> 
> After all, if an immutable structure is embedded in another one, that
> doesn't automatically imply that the containing structure has to be
> immutable too.  Hence, a const pointer to the inner structure doesn't
> automatically yield a const pointer to the outer one.

I think in that case it'd be better, to at least make an informed decision
on that instead of just dropping the const qualifier.

-- 
Regards,

Sakari Ailus