tree a93d841ce0104c8e19e6e37253df8512e0113a6e
parent 929423fa83e5b75e94101b280738b9a5a376a0e1
author Ross Lagerwall <ross.lagerwall@citrix.com> 1438349442 +0100
committer David Vrabel <david.vrabel@citrix.com> 1438699319 +0100

xen/events/fifo: Handle linked events when closing a port

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 and thus cannot be linked onto the correct queue.

When a channel is closed and the event is still linked into a queue,
ensure that it is unlinked before completing.

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 the missing interrupts (and subsequent disk stalls etc.)
when offlining a CPU.

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>