Re: wait_on_irq, CPU1

Andrea Arcangeli (andrea@suse.de)
Tue, 28 Dec 1999 23:59:12 +0100 (CET)


On Tue, 28 Dec 1999, Manfred Spraul wrote:

>The second CPU is in a bottom half handler, ie most likely the local
>interrupts are enabled.

That's why I suggested SYSRQ+P as first thing :).

> I though about a tiny patch which calls
>smp_call_function() in wait_on_irq(): the IPI would call a stripped down
>version of show_registers().

FYI: Andi just wrote the code to do that for the wait_on_bh case for other
needs, extending original's Andi's patch for wait_on_irq as well should be
trivial.

>What do you think?

I of course agree it's a good idea to get more stack traces and less hang
reports from users. For debugging make no difference because SYSRQ+P
should really show the whole stack trace and CPU where the irq is running
and not only the mere EIP.

BTW, it's possible to drive the IO-APIC to send the IPI with NMI priority
(I did that for other reasons recently) and doing that we'll get a nice
stack trace even without the NMI oopser.

Andrea

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