Messages in this thread | | | Date | Thu, 25 Mar 2010 21:51:24 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] Prevent nested interrupts when the IRQ stack is near overflowing v2 |
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* David Miller <davem@davemloft.net> wrote:
> From: Linus Torvalds <torvalds@linux-foundation.org> > Date: Thu, 25 Mar 2010 12:10:22 -0700 (PDT) > > > On Thu, 25 Mar 2010, Ingo Molnar wrote: > >> > >> So the patch below should at most trigger bugs in areas that need fixing > >> anyway, and i'm quite sure that under no circumstance would it cause > >> unforeseen problems in 'thousands of drivers'. > > > > If we do this, then we should just remove all the IRQF_DISABLED code in > > kernel/irq/manage.c too, and basically make IRQF_DISABLED a clear no-op > > (still leave it around as a #define, to not break any users). > > FWIW, I'm currently using IRQF_DISABLED for virtual network device > interrupts on sparc64 as a workaround for some stack overflow issues.
I think IRQF_DISABLED is the sanest method to run IRQs: it's the most atomic, thus most cache-efficient, it doesnt nest, and it's also a tiny bit faster to execute, by a few instructions (on x86).
> This change will just force me to work harder to find out a better way to > fix the problem, so don't let my issue hold this back, it's just an FYI...
The patch i sent basically hardcodes IRQF_DISABLED - so it should fix your problem automatically. IRQF_DISABLED will become an unconditional thing, and we can then also remove it.
Ingo
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