Re: [PATCH 1/5] driver core: Add simple parameter checks for APIs device_(for_each|find)_child()

[Greg Kroah-Hartman]

On Tue, Aug 13, 2024 at 06:00:30PM +0800, quic_zijuhu wrote:
> On 8/13/2024 5:44 PM, Greg Kroah-Hartman wrote:
> > On Sun, Aug 11, 2024 at 08:18:07AM +0800, Zijun Hu wrote:
> >> From: Zijun Hu <quic_zijuhu@xxxxxxxxxxx>
> >>
> >> Add simple parameter checks for APIs device_(for_each|find)_child() and
> >> device_for_each_child_reverse().
> > 
> > Ok, but why?  Who is calling this with NULL as a parent pointer?
> > 
> > Remember, changelog text describes _why_ not just _what_ you are doing.
> > 
> 
> For question why ?
> 
> The main purpose of this change is to make these APIs have *CONSISTENT*
> parameter checking (!parent || !parent->p)
> 
> currently, 2 of them have checking (!parent->p), the other have checking
> (!parent), the are INCONSISTENT.
> 
> 
> For question who ?
> device_find_child() have had such checking (!parent), that maybe mean
> original author has concern that parent may be NULL.
> 
> Moreover, these are core driver APIs, it is worthy checking input
> parameter strictly.

Not always, no, don't check for things that will not happen, otherwise
you are checking for no reason at all.

thanks,

greg k-h