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Date:   Thu, 26 May 2022 11:00:54 +0200
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Subject: Re: [PATCH] Revert "linux/types.h: remove unnecessary __bitwise__"
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To:     Linus Torvalds <torvalds@linux-foundation.org>,
        Bjorn Helgaas <helgaas@kernel.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        "Michael S . Tsirkin" <mst@redhat.com>, llvm@lists.linux.dev,
        "open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>
References: <20220525144638.293934-1-helgaas@kernel.org>
 <CAHk-=whk=ygWsxt=1HhndCwjtXdga9sPmkxFGby5PJWRk5yx9Q@mail.gmail.com>
From:   Jiri Slaby <jirislaby@kernel.org>
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On 25. 05. 22, 18:02, Linus Torvalds wrote:
> On Wed, May 25, 2022 at 7:46 AM Bjorn Helgaas <helgaas@kernel.org> wrote:
>>
>> This reverts commit c724c866bb70cb8c607081a26823a1f0ebde4387.
>>
>> Jiri Slaby reported that c724c866bb70 ("linux/types.h: remove unnecessary
>> __bitwise__") broke userspace, including open-iscsi, because it uses
>> __bitwise__.
>>
>> Restore the __bitwise__ definition.
> 
> Hmm.
> 
> Presumably it's only the uapi case that actually wants to re-instate it.
> 
> And I'd rather make that "__bitwise__" case explicitly special, with a
> comment about why it exists when the kernel itself doesn't use it.
> 
> IOW, rather than the revert, maybe something like the below
> (whitespace-damaged) instead?
> 
> Jiri, does something like this work for you?

Yes, thanks.

> ---
>   include/uapi/linux/types.h | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/include/uapi/linux/types.h b/include/uapi/linux/types.h
> index c4dc597f3dcf..308433be33c2 100644
> --- a/include/uapi/linux/types.h
> +++ b/include/uapi/linux/types.h
> @@ -26,6 +26,9 @@
>   #define __bitwise
>   #endif
> 
> +/* The kernel doesn't use this legacy form, but user space does */
> +#define __bitwise__ __bitwise
> +
>   typedef __u16 __bitwise __le16;
>   typedef __u16 __bitwise __be16;
>   typedef __u32 __bitwise __le32;


-- 
js
suse labs