Re: [Xen-devel] [PATCH v3 18/18] xen/arm: IRQ: Handle multiple action per IRQ

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 04/17/2014 01:27 PM, Ian Campbell wrote:
> On Thu, 2014-04-17 at 13:18 +0100, Julien Grall wrote:
>> On 04/17/2014 12:36 PM, Ian Campbell wrote:
>>> On Thu, 2014-04-17 at 12:22 +0100, Julien Grall wrote:
>>>> On 04/17/2014 12:15 PM, Jan Beulich wrote:
>>>>>>>> On 17.04.14 at 12:36, <julien.grall@xxxxxxxxxx> wrote:
>>>>>> In Linux case, they are safe because they are using a single linked list.
>>>>>
>>>>> And is there a strong reason for us to use a doubly linked one?
>>>>
>>>> My first version was single-linked list... Ian asked me to use generic
>>>> list on V1 to avoid open code.
>>>
>>> I also suggested that you could import a single linked list
>>> implementation if you thought it would be better.
>>>
>>>> I was looking to port llist.h from Linux but it seems a bit overkill for
>>>> action list.
>>>
>>> I don't see why. I'm sure there are other potential uses of singly
>>> linked lists which people just used a double list because it was simpler
>>> at the time.
>>
>>
>> They are using xchg and AFAIU it's not possible to delete an element
>> anywhere in the list. See:
>>
>> http://lxr.free-electrons.com/source/include/linux/llist.h
> 
> Hrm, I thought Linux had a standard singly link list available too, oh
> well.
> 
> Another option would be to delete things using the rcu mechanisms
> perhaps.

Ok. Unless if you strongly disagree, I will stick into the "next" field.

Using rcu... doesn't seems the right things for an IRQ management code.


-- 
Julien Grall

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