Re: [Xen-devel] [PATCH for-4.5 7/8] xen/irq: Handle multiple action per IRQ

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 24.02.14 at 15:08, Julien Grall <julien.grall@xxxxxxxxxx> wrote:
> (Adding Jan for x86 part).
> 
> On 02/20/2014 09:29 PM, Julien Grall wrote:
>> Hi Ian,
>> 
>> On 02/19/2014 11:55 AM, Ian Campbell wrote:
>>> On Fri, 2014-01-24 at 16:43 +0000, Julien Grall wrote:
>>>> On ARM, it may happen (eg ARM SMMU) to setup multiple handler for the same
>>>> interrupt.
>>>
>>> Mention here that you are therefore creating a linked list of actions
>>> for each interrupt.
>>>
>>> If you use xen/list.h for this then you get a load of helpers and
>>> iterators which would save you open coding them.
>> 
>> After thinking, using xen/list.h won't really remove open code, except
>> removing "action_ptr" in release_dt_irq.
>> 
>> Calling release_dt_irq to an IRQ with multiple action shouldn't be
>> called often. Therefore, having both prev and next is a waste of space.
> 
> Jan, as it's common code, do you have any thoughts?

In fact I'm not convinced this action chaining is correct in the first
place, as mentioned by Ian too (considering the potential sharing
between hypervisor and guest). Furthermore, if this is really just
about IOMMU handlers, why can't the SMMU code register a single
action and disambiguate by the dev_id argument passed to the
handler?

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel