Re: [RFC PATCH] x86 NMI-safe INT3 and Page Fault (v5)

[Mathieu Desnoyers <compudj@krystal.dyndns.org>]

* Andi Kleen (andi@firstfloor.org) wrote:
> Mathieu Desnoyers <compudj@krystal.dyndns.org> writes:
> >
> > It uses RCU-style updates and has been designed to be lockless from the
> > ground up.
> 
> RCU is not necessarily NMI safe. In most cases RCU needs writer locks
> which you cannot do with NMIs.
> 
> -Andi
> 

RCU-style updates are done outside of NMIs, in sleepable context. That's
just required when the probes connected on markers must be
registered/unregistered.

The NMI context is the RCU read side. It only have to get the probe
function pointers to call along with the private data pointers.

Mathieu


-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68