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[Xen-devel] RE: [PATCH 1/4] x86/HPET: fix initialization order

To: Jan Beulich <JBeulich@xxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-devel] RE: [PATCH 1/4] x86/HPET: fix initialization order
From: "Wei, Gang" <gang.wei@xxxxxxxxx>
Date: Sat, 12 Mar 2011 17:29:12 +0800
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Thread-topic: [PATCH 1/4] x86/HPET: fix initialization order
Jan Beulich wrote on 2011-03-11:
> At least the legacy path can enter its interrupt handler callout while 
> initialization is still in progress - that handler checks whether
> ->event_handler is non-NULL, and hence all other initialization must
> happen before setting this field.
> Do the same to the MSI initialization just in case (and to keep the code in 
> sync).
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

Acked-by: Wei Gang <gang.wei@xxxxxxxxx>

The only bogus case for old code should be: one PIT interrupt came to a 
non-boot cpu before the boot cpu changes HPET to legacy mode, and this PIT 
interrupt was pending until boot cpu initialized the .event_handler with the 
spin lock & rw lock uninitialized. But it is still a possible bug. I support 
make the fix go into 4.1 and 4.0.


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