Re: [PATCH] trivial: disable sparse' warning for "potentiallyexpensive pointer subtraction".

From: Jiri Kosina
Date: Thu Sep 23 2010 - 07:24:08 EST


On Fri, 20 Aug 2010, Bernd Petrovitsch wrote:

> Rationale: With a somewhat current gcc (or a somewhat sane peephole
> optimizer), the (expensive) "div" is converted to a "shift" or
> "mul" with the inverse.
> This warning is disabled per default in sparse but the "-Wall" in
> the kernels CFLAGS enables it.
>
> Signed-off-by: Bernd Petrovitsch <bernd@xxxxxxxxxx>
> ---
> This patch is trivial and affects only calls to sparse (read: make C=1) and
> removes false warnings. So it should be considered for inclusion immediately.
>
> Sorry for the long Cc: - I included everyone in the thread and added
> linux-kbuild@ (as it IMHO belongs there) and trivial@ (because of the
> complexity of the patch).
>
> Makefile | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index f3bdff8..851c0fa 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -330,7 +330,7 @@ PERL = perl
> CHECK = sparse
>
> CHECKFLAGS := -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ \
> - -Wbitwise -Wno-return-void $(CF)
> + -Wbitwise -Wno-return-void -Wno-ptr-subtraction-blows $(CF)
> CFLAGS_MODULE =
> AFLAGS_MODULE =
> LDFLAGS_MODULE =

What is the status of this patch? I don't see it Nacked, but it's not in
linux-next either.

Thanks,

--
Jiri Kosina
SUSE Labs, Novell Inc.
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