Re: [PATCH] overflow: Update is_non_negative() and is_negative() comment

Dan Carpenter
2026-01-03T17:01:50Z

On Sat, Jan 03, 2026 at 12:10:45PM +0100, Vincent Mailhol wrote:
> On 03/01/2026 at 11:02, Dan Carpenter wrote:
> > Thanks Randy, for sending this to me. I'm on the sparse list, but
> > I've been on vacation and haven't caught up with my email.
>
> Welcome back, hope you enjoyed your holidays!
>
> >I can easily silence this in Smatch.
>
> Thanks. I ran this locally, I can confirm that this silences the
> warning. So:
>
> Tested-by: Vincent Mailhol <mailhol@kernel.org>
>
> > diff --git a/check_unsigned_lt_zero.c b/check_unsigned_lt_zero.c
> > index bfeb3261f91d..ac3e650704ce 100644
> > --- a/check_unsigned_lt_zero.c
> > +++ b/check_unsigned_lt_zero.c
> > @@ -105,7 +105,8 @@ static bool is_allowed_zero(struct expression *expr)
> > strcmp(macro, "STRTO_H") == 0 ||
> > strcmp(macro, "SUB_EXTEND_USTAT") == 0 ||
> > strcmp(macro, "TEST_CASTABLE_TO_TYPE_VAR") == 0 ||
> > - strcmp(macro, "TEST_ONE_SHIFT") == 0)
> > + strcmp(macro, "TEST_ONE_SHIFT") == 0 ||
> > + strcmp(macro, "check_shl_overflow") == 0)
>
> But, for the long term, wouldn't it better to just ignore all the code
> coming from macro extensions instead of maintaining this allow-list?
>

Of course, that idea occured to me, but so far the allow list is not
very burdensome to maintain. I maybe should disable it for all
macros unless the --spammy option is used...

regards,
dan carpenter