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

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

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.

Ian.



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