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From:   Menglong Dong <menglong8.dong@gmail.com>
Date:   Thu, 18 Mar 2021 09:48:14 +0800
Message-ID: <CADxym3bwqs9e2WKX8uOTzyYKnyTgmW4FT+N2m5hydfBJV3fqXQ@mail.gmail.com>
Subject: Re: [PATCH v4 RESEND net-next] net: socket: use BIT() for MSG_*
To:     David Laight <David.Laight@aculab.com>
Cc:     Guenter Roeck <linux@roeck-us.net>,
        Andy Shevchenko <andy.shevchenko@gmail.com>,
        "kuba@kernel.org" <kuba@kernel.org>,
        "davem@davemloft.net" <davem@davemloft.net>,
        "axboe@kernel.dk" <axboe@kernel.dk>,
        "viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
        "herbert@gondor.apana.org.au" <herbert@gondor.apana.org.au>,
        "dong.menglong@zte.com.cn" <dong.menglong@zte.com.cn>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>
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On Wed, Mar 17, 2021 at 11:12 PM David Laight <David.Laight@aculab.com> wrote:
>
...
>
> Isn't MSG_CMSG_COMPAT an internal value?
> Could it be changed to 1u << 30 instead of 1u << 31 ?
> Then it wouldn't matter if the high bit of flags got replicated.
>

Yeah, MSG_CMSG_COMPAT is an internal value, and maybe
it's why it is defined as 1<< 31, to make it look different.

I think it's a good idea to change it to other value which is
not used, such as 1u<<21.

I will test it and resend this patch later, thanks~

With Regards,
Menglong Dong