Re: [Xen-devel] [RFC PATCH] dpci: Put the dpci back on the list if running on another CPU.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.03.15 at 18:44, <konrad.wilk@xxxxxxxxxx> wrote:
> As you can see to preserve the existing functionality such as
> being able to schedule N amount of interrupt injections
> for the N interrupts we might get - I modified '->masked'
> to be an atomic counter.

Why would that be? When an earlier interrupt wasn't fully handled,
real hardware wouldn't latch more than one further instance either.

> The end result is that we can still live-lock. Unless we:
>  - Drop on the floor the injection of N interrupts and
>    just deliever at max one per VMX_EXIT (and not bother
>    with interrupts arriving when we are in the VMX handler).

I'm afraid I again don't see the point here.

>  - Alter the softirq code slightly - to have an variant
>    which will only iterate once over the pending softirq
>    bits per call. (so save an copy of the bitmap on the
>    stack when entering the softirq handler - and use that.
>    We could also xor it against the current to catch any
>    non-duplicate bits being set that we should deal with).

That's clearly not an option: The solution should be isolated
to DPCI code, i.e. without altering existing behavior in other
(more generic) components.

Jan


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