Messages in this thread | | | Date | Fri, 8 May 2009 11:37:57 +0200 | From | Andi Kleen <> | Subject | Re: [PATCH] x86 MCE: shut up lockdep warning |
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> - it works around a lockdep warning > > - you did not realize the real bug while the warning was plain
Well I'm not sure you understood it either :) Actually I'm pretty sure you did not. It would have been good if you had awaited proper review comments before commiting your patch.
I don't think here's really a real bug because cpu hotunplug is single threaded anyways (cpu add remove lock) and we don't do multiple discoveries in parallel.
The reason the lock is there is only during bringup with multiple CPUs doing this in parallel on initial bootup. But we can't race against cpu hotunplug there because there's not hotunplug before the system is up with all configured CPUs.
So I think any way of shutting up lockdep is fine here and your patch is overkill and disables interrupts unnecessarily.
> - plus the patch introduces a fragile (because complex) > work_on_cpu() call into the CPU hotplug path, which could have > caused followup regressions.
That's a reasonable point, but doesn't seem strong enough to do full irq disabling. A better fix would be to find some other way to shut off this lockdep warning for this case. Is there such a way?
-Andi
-- ak@linux.intel.com -- Speaking for myself only.
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