Re: net: rnpgbe: Pass an expression directly in rnpgbe_rm_adapter()

[Dan Carpenter]

On Wed, Jul 15, 2026 at 08:45:48PM +0200, Markus Elfring wrote:
> 
> Jonathan Corbet provided the following information.
> 
> “…
> But Herbert's patch added a line which dereferences the pointer prior to the check. That, of course, is a bug.
> …”
> 

Notice that it says "dereferences" not "does pointer math".

> 
> >                                                       Note, I didn't
> > study the C standard
> 
> I hope that clarification approaches can evolve further according to this information source.
> 
> 
> >                      if the compiler is free to optimize out
> > do_something() also in the 2nd case, but at least today gcc doesn't.
> 
> Can development interests grow also according to another clarification approach?
> 
> Does &((struct name *)NULL -> b) cause undefined behaviour in C11?
> https://stackoverflow.com/questions/26906621/does-struct-name-null-b-cause-undefined-behaviour-in-c11
> 
> 
> 
> Would you prefer to omit a “sanity check” in the discussed function implementation?
> 

This is irrelevant.

In C writing if (!p) and if (p == NULL) are always equivalent but weirdly
the NULL doesn't have to zero.  It's part of the C FAQ.
https://c-faq.com/null/machexamp.html It's just a bit of fun trivia that
doesn't really matter unless you have a time machine.  Even if you invented
a time machine, the code here would still be fine because we have a NULL
test before dereferencing the results of our pointer math.

regards,
dan carpenter