Re: PTE access rules & abstraction

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Thu, 2008-09-25 at 11:15 -0700, Jeremy Fitzhardinge wrote:
> The ptep_modify_prot_start/commit pair specifies a single pte update in
> such a way to allow more implementation flexibility - ie, there's no
> naked requirement for an atomic fetch-and-clear operation.  I chose the
> transaction-like terminology to emphasize that the start/commit
> functions must be strictly paired; there's no way to fail or abort the
> "transaction".  A whole group of those start/commit pairs can be batched
> together without affecting their semantics.

I still can't see the point of having now 3 functions instead of just
one such as ptep_modify_protection(). I don't see what it buys you other
than adding gratuituous new interfaces.

Ben;.