On Mon, 2009-03-02 at 09:55 -0800, Andrew Morton wrote: > On Mon, 02 Mar 2009 13:21:17 +0100 Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > > > > People are playing odd games with IRQF_DISABLED, remove it. > > > > Its not reliable, since shared interrupt lines could disable it for you, > > and its possible and allowed for archs to disable IRQs to limit IRQ nesting. > > > > Therefore, simply mandate that _ALL_ IRQ handlers are run with IRQs disabled. > > > > [ This _should_ not break anything, since we've mandated that IRQ handlers > > _must_ be able to deal with this for a _long_ time ] > > > > IRQ handlers should be fast, no if buts and any other exceptions. We also have > > plenty instrumentation to find any offending IRQ latency sources. > > Changelog is a bit cruddy. What are these "odd games" and why are they > so serious as to warrant a fairly drastic-looking patch? See for example the stuff David Brownell was trying to pull off. I was -- naively it turns out -- hoping it would be a simple matter of cleaning up, as lockdep has been doing this for a long while now. > Where are these odd games being played, and what are the implications > to those codesites of having their ball taken away? etc. Generation of terrible IRQ latency, or in David's case, more pain for the abuse of the genirq layer. > wrt the patch itself - it would make life easier if we were to leave > the IRQF_DISABLED definition in place for a while. I'm counting 47 new > additions of references to IRQF_DISABLED in linux-next/-mm. It would > grease the wheels a bit were these things (and out-of-tree drivers) to > not instabreak. One could add a nice runtime warning at request_irq() > time, leave that in place until everything is fixed up. Sure, can do. -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
