Messages in this thread | | | From | Keith Owens <> | Subject | Re: i386 IPI handlers running with hardirq_count == 0 | Date | Fri, 30 Jun 2006 03:00:42 +1000 |
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Andi Kleen (on 29 Jun 2006 13:25:38 +0200) wrote: >Andrew Morton <akpm@osdl.org> writes: > >> On Thu, 29 Jun 2006 19:01:17 +1000 >> Keith Owens <kaos@ocs.com.au> wrote: >> >> > Macro arch/i386/kernel/entry.S::BUILD_INTERRUPT generates the code to >> > handle an IPI and call the corresponding smp_<name> C code. >> > BUILD_INTERRUPT does not update the hardirq_count for the interrupted >> > task, that is left to the C code. Some of the C IPI handlers do not >> > call irq_enter(), so they are running in IRQ context but the >> > hardirq_count field does not reflect this. For example, >> > smp_invalidate_interrupt does not set the hardirq count. >> > >> > What is the best fix, change BUILD_INTERRUPT to adjust the hardirq >> > count or audit all the C handlers to ensure that they call irq_enter()? >> > >> >> The IPI handlers run with IRQs disabled. Do we need a fix? > >They have to because if there was another interrupt it would execute >IRET and then clear the NMI flag in the hardware and allow nested NMIs >which would cause all sorts of problems. > >The only reason to change it would be complex callbacks in the >current handlers using notifier chains. Maybe if they're that complex they >should become simpler?
My question has nothing to do with NMI. I am querying inconsistent behaviour amongst normal IPIs, this list :-
i386 function irq_enter? smp_apic_timer_interrupt yes smp_call_function_interrupt yes smp_error_interrupt yes smp_invalidate_interrupt no - why smp_reschedule_interrupt no (does not need it) smp_spurious_interrupt yes smp_thermal_interrupt yes
x86_64 function irq_enter? mce_threshold_interrupt yes smp_apic_timer_interrupt yes smp_call_function_interrupt yes smp_error_interrupt yes smp_invalidate_interrupt no - why smp_reschedule_interrupt no (does not need it) smp_spurious_interrupt yes smp_thermal_interrupt yes
That is just the mach-default list, I have not checked the platforms like voyager.
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