Re: [RFC][PATCH] kmap_atomic_push

Peter Zijlstra
2009-10-08T16:29:22Z

On Thu, 2009-10-08 at 17:53 +0200, Ingo Molnar wrote:
> * Peter Zijlstra <peterz@infradead.org> wrote:
>
> > The below patchlet changes the kmap_atomic interface to a stack based
> > one that doesn't require the KM_types anymore.
> >
> > This significantly simplifies some code (more still than are present
> > in this patch -- ie. pte_map_nested can go now)
> >
> > This obviously requires that push and pop are matched, I fixed a few
> > cases that were not properly nested, the (x86) code checks for this
> > and will go BUG when trying to pop a vaddr that isn't the top one so
> > abusers should be rather visible.
>
> Looks great IMO! Last i proposed this i think either Andrew or Avi had
> second thoughts about the hard-to-calculate worst-case mapping limit -
> but i dont think that's a big issue.

That would've been me ;-)

> Lets not change the API names though - the rule is that map/unmap must
> be properly nested.

Right, so I did that full rename just so that people wouldn't get
confused or something, but if both you and Linus think it should remain:
kmap_atomic() and kunmap_atomic(), I can certainly undo that part.