[PATCH] Document Linux's memory barriers [try #2]

[David Howells]

Alan Cox <alan at redhat.com> wrote:

> 	spin_lock(&foo->lock);
> 	writel(0, &foo->regnum);

I presume there only needs to be an mmiowb() here if you've got the
appropriate CPU's I/O memory window set up to be weakly ordered.

> 	writel(1, &foo->data);
> 	mmiowb();
> 	spin_unlock(&foo->lock);

David