Date: Wed, 13 Dec 2017 17:45:54 +0000
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Jakub Kicinski <kubakici@wp.pl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH] new byteorder primitives - ..._{replace,get}_bits()
Message-ID: <20171213174554.GE21978@ZenIV.linux.org.uk>
References: <20171212120409.64b6362e@cakuba.netronome.com>
 <20171212234856.GZ21978@ZenIV.linux.org.uk>
 <20171212155933.03c88eab@cakuba.netronome.com>
 <20171213003659.GA21978@ZenIV.linux.org.uk>
 <20171212170437.4b129e50@cakuba.netronome.com>
 <20171213013056.GB21978@ZenIV.linux.org.uk>
 <20171212173528.340cd002@cakuba.netronome.com>
 <20171213015125.GC21978@ZenIV.linux.org.uk>
 <20171212184400.13b27cf8@cakuba.netronome.com>
 <20171213142212.GD21978@ZenIV.linux.org.uk>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20171213142212.GD21978@ZenIV.linux.org.uk>
User-Agent: Mutt/1.9.0 (2017-09-02)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 934
Lines: 22

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?