@Andy, its linux-kernel@vger, not lkml@vger :-) On Tue, May 24, 2016 at 11:36:29AM +0200, Borislav Petkov wrote: > On Tue, May 24, 2016 at 10:59:45AM +0200, Peter Zijlstra wrote: > > Which use a sequence of: in_nmi(), in_irq(), in_softirq() to pick 1 out > > of 4 possible contexts. > > So should we make it cleaner and explicit and define a 5th context of > priorities higher than NMI? > > There's some room between those two: > > * NMI_MASK: 0x00100000 > * PREEMPT_NEED_RESCHED: 0x80000000 >
A lot of pain; we'd have to go grow a whole bunch of things to 5. Also, I don't think 5 is enough to model all the IST nesting. I'm also not sure we really care too much; IST stuff is relatively rare. It just means we can loose IST based trace events and the like, because its treated as recursion. So I think keeping it at 4 is fine, but we do want to make a semi concious choice on how we map back to those 4.
