On Sat, 5 Jul 2014, Joe Perches wrote:
> Because gcc issues a complaint about any pointer format with %#p,
> remove the use of SPECIAL to prefix 0x to various pointer types.
>
> There are no uses in the kernel tree of %#p.
>
> This removes the capability added by commit 725fe002d315
> ("vsprintf: correctly handle width when '#' flag used in %#p format").
>
> There are some incidental message logging output changes of %pa
> uses with this change. None are in seq output so there are no
> api changes.
>
> Signed-off-by: Joe Perches <j...@perches.com>
> ---
>
> Fine by me, here...
>
> On Sat, 2014-07-05 at 21:25 +0100, Maciej W. Rozycki wrote:
> > On Sat, 5 Jul 2014, Joe Perches wrote:
> >
> > > > > I don't think %#p is valid so it
> > > > > shouldn't have been set by #.
> > > >
> > > > Huh? As recently as last Wednesday you pointed me at the specific
> > > > commit
> > > > from Grant that made it valid (GCC format complaints aside).
> > >
> > > Those gcc complaints are precisely the thing
> > > that makes it invalid.
> >
> > So enforce that in code then, clear the SPECIAL flag where appropriate
> > and do not try to handle it in one place while leaving other ones to
> > behave randomly (i.e. a supposedly fixed field width varies depending on
> > the two uppermost digits). Please note that it's only your proposed
> > change that introduces that randomness, right now code does what's
> > supposed and documented to, except a bit inconsistently.
> >
> > > I believe you're tilting at windmills.
> > >
> > > Hey, it works sometimes. Knock yourself out.
> >
> > I pointed out an inconsistency with the intent to propose a fix once a
> > consensus have been reached, one way or another. And I think shifting the
> > inconsistency to a different place, which is what your proposal does,
> > isn't really a complete solution, although I do recognise the improvement.
Conceptually good, thanks for your effort, but you still need to clear
SPECIAL in `pointer' and maybe elsewhere, as that'll have been set for the
case concerned in `format_decode' by this code:
case '#': spec->flags |= SPECIAL; break;
(that doesn't check what follows) and then respected once `number' is
reached. E.g.:
char *pointer(const char *fmt, char *buf, char *end, void *ptr,
struct printf_spec spec)
{
int default_width = 2 * sizeof(void *);
spec.flags &= ~SPECIAL;
or suchlike. Sorry to have been unclear about it.
Note that obviously GCC will only complain about `#' if the format is
constant, there's no way for it to work through a variable format, e.g.:
{
char *f;
void *const p = NULL;
printk("%#p\n", p);
f = kstrdup("%#p\n", GFP_KERNEL);
printk(f, p);
kfree(f);
}
-- it'll complain only about the first `printk', not the second.
Maciej
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