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



On Tue, 2014-04-01 at 14:52 +0100, Julien Grall wrote:
> On 04/01/2014 02:23 PM, Ian Campbell wrote:
> > On Tue, 2014-04-01 at 14:13 +0100, Julien Grall wrote:
> >>>>  - I need to use 2 variables to search for an element in a list as there 
> >>>> is
> >>>>  no way to know after the end of the loop if we found or not an element.
> >>>
> >>> You've written that a bit weirdly IMHO.
> >>>
> >>> list_for_each(...)
> >>>    if (not the one we want)
> >>>   continue
> >>>    free the one we wanted
> >>>    break;
> >>>
> >>> don't worry about warning on a non-existent IRQ, or set a simple
> >>> boolean.
> >>
> >> We have to worry about non-existent action otherwise Xen may segfault...
> > 
> > Why? If it doesn't exist we don't do anything.
> > 
> > 
> 
> We can't free in the loop because the action may be used on another CPU
> at the same it. (see "active" loop at the end). So I still need two
> variables (one for the loop and one for the real action).

Perhaps the "goto found" pattern might help here then?

Ian.



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