Messages in this thread | | | Date | Thu, 25 Mar 2010 17:27:37 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] Prevent nested interrupts when the IRQ stack is near overflowing v2 |
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* Linus Torvalds <torvalds@linux-foundation.org> wrote:
[...] > > Now, it's also true that our IRQ infrastructure handlers _could_ be smarter, > and make the whole problem less likely to happen. > > In particular, it's probably true that especially on modern hardware with > multiple cores, and especially when you do _not_ have irq sharing (which is > the common case these days for things like network drivers that can use > MSI), we really would be better off having the irq disabled over the whole > thing, and on some interrupt controllers it might even be worth it to do the > old optimization of not masking-and-acking, but just acking.
Yes.
> But see above. This is _not_ something that a driver can do any more. They > don't know whether the interrupt might end up being shared. Just blindly > setting IRAF_DISABLED in a driver is _not_ the answer. But being smarter in > the generic irq handler code might work. > > And then, what we could do, is to mark the drivers that absolutely _must_ be > able to nest specially. Like the IDE driver when in PIO mode. Or maybe the > SCSI drivers, if they still depend on that timer interrupt happening while > they are busy.
I think the patch as posted solves a real problem, but also perpetuates a bad situation.
At minimum we should print a (one-time) warning that some badness occured. That would push us either in the direction of improving drivers, or towards improving the generic code.
Thanks,
Ingo
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