virtio: support unlocked queue poll
authorMichael S. Tsirkin <mst@redhat.com>
Tue, 9 Jul 2013 10:19:18 +0000 (13:19 +0300)
committerDavid S. Miller <davem@davemloft.net>
Tue, 9 Jul 2013 19:45:37 +0000 (12:45 -0700)
commitcc229884d3f77ec3b1240e467e0236c3e0647c0c
treea2617adb191288d049629f911b7fef7038557a8e
parent01276ed2424eb78c95461545410923d5da154d31
virtio: support unlocked queue poll

This adds a way to check ring empty state after enable_cb outside any
locks. Will be used by virtio_net.

Note: there's room for more optimization: caller is likely to have a
memory barrier already, which means we might be able to get rid of a
barrier here.  Deferring this optimization until we do some
benchmarking.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
drivers/virtio/virtio_ring.c
include/linux/virtio.h