Re: [RFC] should VM_BUG_ON(cond) really evaluate cond

On Fri, 2011-10-28 at 04:52 +0200, Eric Dumazet wrote:

Le vendredi 28 octobre 2011 à 02:44 +0100, Ben Hutchings a écrit :

quoted

Whether or not it needs to provide any ordering guarantee, atomic_read()
must never read more than once, and I think that requires the volatile
qualification.  It might be clearer to use the ACCESS_ONCE macro,
however.

Where this requirement comes from ?

That is the conventional behaviour of 'atomic' operations, and callers
may depend on it.

Maybe then introduce atomic_read_once() for users really needing it :)

ACCESS_ONCE will force the read/move instruction I try to avoid :(

[...]

I'm sure you can find some other way to avoid it.

Ben.

-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.