Re: [Xen-devel] [PATCH 2/9] x86/IRQ: deal with move cleanup count state in fixup_irqs()

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Tue, May 07, 2019 at 01:28:36AM -0600, Jan Beulich wrote:
> >>> On 03.05.19 at 17:21, <roger.pau@xxxxxxxxxx> wrote:
> > On Mon, Apr 29, 2019 at 05:23:20AM -0600, Jan Beulich wrote:
> >> ---
> >> TBD: The proper recording of the IPI destinations actually makes the
> >>      move_cleanup_count field redundant. Do we want to drop it, at the
> >>      price of a few more CPU-mask operations?
> > 
> > AFAICT this is not a hot path, so I would remove the
> > move_cleanup_count field and just weight the cpu bitmap when needed.
> 
> FTR: It's not fully redundant - the patch removing it that I had
> added was actually the reason for seeing the ASSERT() trigger
> that you did ask to add in patch 1. The reason is that the field
> serves as a flag for irq_move_cleanup_interrupt() whether to
> act on an IRQ in the first place. Without it, the function will
> prematurely clean up the vector, thus confusing subsequent
> code trying to do the cleanup when it's actually due.

So weighing desc->arch.old_cpu_mask is not equivalent to
move_cleanup_count?

Thanks, Roger.

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