virtio ring: inline function to check for events
authorMichael S. Tsirkin <mst@redhat.com>
Thu, 19 May 2011 23:10:27 +0000 (02:10 +0300)
committerRusty Russell <rusty@rustcorp.com.au>
Mon, 30 May 2011 01:44:14 +0000 (10:44 +0930)
commitbf7035bf20563a6cadcb9e870406e7b21daf5e30
tree19eda109916e7ba9e4c531602b6efb5d1ef33c2a
parent770b31a85e000b0194974922f238a30ade4246b6
virtio ring: inline function to check for events

With the new used_event and avail_event and features, both
host and guest need similar logic to check whether events are
enabled, so it helps to put the common code in the header.

Note that Xen has similar logic for notification hold-off
in include/xen/interface/io/ring.h with req_event and req_prod
corresponding to event_idx + 1 and new_idx respectively.
+1 comes from the fact that req_event and req_prod in Xen start at 1,
while event index in virtio starts at 0.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
include/linux/virtio_ring.h