From: Cornelia Huck <cornelia.huck@de.ibm.com>
Subject: Re: [PATCH] linux/types.h: enable endian checks for all sparse builds
Date: Thu, 8 Dec 2016 12:25:53 +0100
Message-ID: <20161208122553.5fa5a09c.cornelia.huck@de.ibm.com>
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Cc: kvm@vger.kernel.org, Neil Armstrong <narmstrong@baylibre.com>,
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	linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org,
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	"David S. Miller" <davem@davemloft.net>
To: "Michael S. Tsirkin" <mst@redhat.com>
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On Thu, 8 Dec 2016 04:29:39 +0200
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> By now, linux is mostly endian-clean. Enabling endian-ness
> checks for everyone produces about 200 new sparse warnings for me -
> less than 10% over the 2000 sparse warnings already there.

Out of curiousity: Where do most of those warnings show up?

> 
> Not a big deal, OTOH enabling this helps people notice
> they are introducing new bugs.
> 
> So let's just drop __CHECK_ENDIAN__. Follow-up patches
> can drop distinction between __bitwise and __bitwise__.
> 
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Suggested-by: Christoph Hellwig <hch@infradead.org>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
> 
> Linus, could you ack this for upstream? If yes I'll
> merge through my tree as a replacement for enabling
> this just for virtio.
> 
>  include/uapi/linux/types.h | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/include/uapi/linux/types.h b/include/uapi/linux/types.h
> index acf0979..41e5914 100644
> --- a/include/uapi/linux/types.h
> +++ b/include/uapi/linux/types.h
> @@ -23,11 +23,7 @@
>  #else
>  #define __bitwise__
>  #endif
> -#ifdef __CHECK_ENDIAN__
>  #define __bitwise __bitwise__
> -#else
> -#define __bitwise
> -#endif
> 
>  typedef __u16 __bitwise __le16;
>  typedef __u16 __bitwise __be16;

FWIW, I like this better than just enabling it for the virtio code.