Re: [Xen-devel] [PATCH v2] xen/events/fifo: Handle linked events when closing a port

[David Vrabel <david.vrabel@xxxxxxxxxx>]

On 31/07/15 14:30, Ross Lagerwall wrote:
> When a channel is closed and the event is still linked into a queue,
> ensure that it is unlinked before completing. If it is not unlinked and
> the port is subsequently reused, events may be missed.
> 
> If the CPU to which the event channel bound is online, spin until the
> event is handled by that CPU. If that CPU is offline, it can't handle
> the event, so clear the event queue during the close, dropping the
> events.
> 
> This fixes missing interrupts (and subsequent disk stalls) when
> offlining a CPU.

The last paragraph should be expanded I think.  How about:

  An event channel bound to a CPU that was offlined may still be linked
  on that CPU's queue.  If this event channel is closed and reused,
  subsequent events will be lost because the event channel is never
  unlinked.

Otherwise,

Reviewed-by: David Vrabel <david.vrabel@xxxxxxxxxx>

David


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