On Sun, 9 Jan 2011, Sergei Shtylyov wrote:
> > static struct field *get_field(void)
> > {
> > struct my_mod *mod = NULL;
> >
> > return &mod->f;
>
> That's another case: offset of 'f' is not 0, unlike the offset of 'request'.
What happens if somebody in the future adds another member to the
musb_request structure in front of the .request member?
Felipe's change is simply good programming practice (although the patch
description could be improved).
> > Now, if change the check:
>
> > --- t.c.orig 2011-01-09 19:06:31.581642000 +0200
> > +++ t.c 2011-01-09 19:05:41.733642000 +0200
> > @@ -26,7 +26,7 @@ static int __init mod_init(void)
> > {
> > struct field *f = get_field();
> >
> > - if (f == NULL)
> > + if (f)
> > pr_info("===> f (%p) is NULL\n", f);
> > else
> > pr_info("===> f (%p) is not NULL\n", f);
>
> > Everything the pointer is considered NULL:
>
> > $ dmesg
> > [1385484.405684] ===> f (0000000c) is NULL
>
> Hm, interesting...
Not as interesting as it may appear. The test is backward, so the fact
that the program printed out "is NULL" means the computer thinks f
really is not NULL.
Alan Stern
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