Re: [tip:perfcounters/core] x86: Add NMI types for kmap_atomic

[Peter Zijlstra <peterz@xxxxxxxxxxxxx>]

On Mon, 2009-06-15 at 20:25 +0200, Ingo Molnar wrote:
> * Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> but ... look at the APIs i propose above. We dont need _any_ 
> 'types'.
> 
> That type enumeration is basically an open-coded allocator. If we do 
> a _real_ allocator (a balanced stack of atomic kmaps) we dont need 
> any of those indices, and all the potential for mismatch goes away 
> as well - a stack nests trivially with IRQ and NMI and arbitrary 
> other contexts.

You want types because:
 - they encode the intent, and can be verified
 - they help keep track of the max nesting depth

In the proposed implementation all type code basically falls away no !
CONFIG_DEBUG_VM, but is kept around for robustness.
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