netdev - Re: [RFC][PATCH] new byteorder primitives

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Message-ID: <20171213174554.GE21978@ZenIV.linux.org.uk>
Date:   Wed, 13 Dec 2017 17:45:54 +0000
From:   Al Viro <viro@...IV.linux.org.uk>
To:     Jakub Kicinski <kubakici@...pl>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH] new byteorder primitives - ..._{replace,get}_bits()

On Wed, Dec 13, 2017 at 02:22:12PM +0000, Al Viro wrote:

> Next question: where do we put that bunch?  I've put it into
> linux/byteorder/generic.h, so that anything picking fixed-endian primitives
> would pick those as well; I hadn't thought of linux/bitfield.h at the time.
> We certainly could put it there instead - it's never pulled by other headers,
> so adding #include <asm/byteorder.h> into linux/bitfield.h is not going to
> cause header order problems.  Not sure...
> 
> Linus, do you have any preferences in that area?

After looking at some of the callers of bitfield.h stuff: it might be useful
to add

static inline void le64p_replace_bits(__le64 *p, u64 v, u64 mask)
{
	__le64 m = cpu_to_le64(mask);
	*p = (*p & ~m) | (cpu_to_le64(v * mask_to_multiplier(mask)) & m);
}

and similar for other types.  Not sure what would be a good name for
host-endian variants - u64p_replace_bits() sounds a bit clumsy.  Suggestions?