xen: correctly check for pending events when restoring irq flags

In xen_restore_fl_direct(), xen_force_evtchn_callback() was being
called even if no events were pending.  This resulted in (depending on
workload) about a 100 times as many xen_version hypercalls as
necessary.

Fix this by correcting the sense of the conditional jump.

This seems to give a significant performance benefit for some
workloads.

There is some subtle tricksy "..since the check here is trying to
check both pending and masked in a single cmpw, but I think this is
correct. It will call check_events now only when the combined
mask+pending word is 0x0001 (aka unmasked, pending)." (Ian)

CC: [email protected]
Acked-by: Ian Campbell <[email protected]>
Signed-off-by: David Vrabel <[email protected]>
Signed-off-by: Konrad Rzeszutek Wilk <[email protected]>

0 files changed, 0 insertions, 0 deletions