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Re: [Xen-devel] [xen-unstable test] 6947: regressions - trouble: broken/fail/pass

  • To: Jan Beulich <JBeulich@xxxxxxxxxx>
  • From: Keir Fraser <keir.xen@xxxxxxxxx>
  • Date: Tue, 03 May 2011 15:09:10 +0100
  • Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
  • Delivery-date: Tue, 03 May 2011 07:13:43 -0700
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  • Thread-topic: [Xen-devel] [xen-unstable test] 6947: regressions - trouble: broken/fail/pass

On 03/05/2011 14:36, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:

>> But the readers in irq context will call lookup_slot() without d->event_lock
>> held? In that case you do need an RCU-aware version of radix-tree.[ch],
>> because lookups can be occurring concurrently with insertions/deletions.
> No, in IRQ context we only need the irq -> pirq translation afaics, and
> that translation doesn't use an allocated object (it instead simply inserts
> the [non-zero] pirq as data item).

Ah well that makes things easier. :-) If a single lock protects all
operations (including lookups) on a particular radix tree then of course we
don't need RCU.

 -- Keir

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