linux-kernel - Re: [PATCH 1/9] kernel: Provide READ_ONCE and ASSIGN

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Message-ID: <20141205213801.3844.qmail@ns.horizon.com>
Date:	5 Dec 2014 16:38:01 -0500
From:	"George Spelvin" <linux@...izon.com>
To:	borntraeger@...ibm.com
Cc:	linux@...izon.com, linux-arch@...r.kernel.org,
	linux-kernel@...r.kernel.org, paulmck@...ux.vnet.ibm.com,
	torvalds@...ux-foundation.org
Subject: Re: [PATCH 1/9] kernel: Provide READ_ONCE and ASSIGN_ONCE

> Of prefer it to match the put_user model, which is (val, ptr). But as long
> as there is your safety (and the whole point of the macro is that it
> figures out the type from the pointer), I guess it doesn't matter too much
> in practice.
> 
> I think my original suggestion also wrote it in lower case, since it
> actually works like a function (well, template, whatever). Again kind of
> like the user copy "functions".
> 
> But I don't care *that* strongly.

That's an excellent point.  But it means that Christian, you're free to
do whatever seems good to you.

I'm not rabid about it, either; I just figure that now is a good time
to think carefully about it.

Personally, after running through some different names that work
with (src,dst) order I'd try the pairs:

	READ_ONCE(var) / WRITE_ONCE(value,var)
or
	LOAD_ONCE(var) / STORE_ONCE(value,var)

Of the two, I think I prefer the latter, because that's what the
operations are called at the hardware level, so it's most evocative of
the actual semantics.  "Assignment" is a higher-level concept.

But as I said, whatever you think best.  I'd just like to advocate for
some actual thinking, because it's going to be all over the kernel and
a pain to change.
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