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virtio: revert host notifiers to old semantics 

The host notifier rework tried both to unify host notifiers across
transports and plug a possible hole during host notifier
re-assignment. Unfortunately, this meant a change in semantics that
breaks vhost and iSCSI+dataplane.

As the minimal fix, keep the common host notifier code but revert
to the old semantics so that we have time to figure out the proper
fix.

Fixes: 6798e245a3 ("virtio-bus: common ioeventfd infrastructure")
Reported-by: Peter Lieven <pl@kamp.de>
Reported-by: Jason Wang <jasowang@redhat.com>
Reported-by: Marc-André Lureau <marcandre.lureau@gmail.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Jason Wang <jasowang@redhat.com>
Tested-by: Jason Wang <jasowang@redhat.com>
Tested-by: Peter Lieven <pl@kamp.de>
This commit is contained in:
Cornelia Huck 2016-06-30 17:31:42 +02:00 committed by Michael S. Tsirkin
parent 01c9742d9d
commit 0830c96d70
1 changed files with 10 additions and 16 deletions
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20
hw/virtio/virtio-bus.c
View File

@ -176,8 +176,8 @@ static int set_host_notifier_internal(DeviceState *proxy, VirtioBusState *bus,
return r; return r;
} }
} else { } else {
virtio_queue_set_host_notifier_fd_handler(vq, false, false);
k->ioeventfd_assign(proxy, notifier, n, assign); k->ioeventfd_assign(proxy, notifier, n, assign);
virtio_queue_set_host_notifier_fd_handler(vq, false, false);
event_notifier_cleanup(notifier); event_notifier_cleanup(notifier);
} }
return r; return r;
@ -251,31 +251,25 @@ int virtio_bus_set_host_notifier(VirtioBusState *bus, int n, bool assign)
{ {
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus); VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
DeviceState *proxy = DEVICE(BUS(bus)->parent); DeviceState *proxy = DEVICE(BUS(bus)->parent);
VirtIODevice *vdev = virtio_bus_get_device(bus);
VirtQueue *vq = virtio_get_queue(vdev, n);
if (!k->ioeventfd_started) { if (!k->ioeventfd_started) {
return -ENOSYS; return -ENOSYS;
} }
k->ioeventfd_set_disabled(proxy, assign);
if (assign) { if (assign) {
/* /*
* Stop using the generic ioeventfd, we are doing eventfd handling * Stop using the generic ioeventfd, we are doing eventfd handling
* ourselves below * ourselves below
*/ *
k->ioeventfd_set_disabled(proxy, true); * FIXME: We should just switch the handler and not deassign the
} * ioeventfd.
/*
* Just switch the handler, don't deassign the ioeventfd.
* Otherwise, there's a window where we don't have an * Otherwise, there's a window where we don't have an
* ioeventfd and we may end up with a notification where * ioeventfd and we may end up with a notification where
* we don't expect one. * we don't expect one.
*/ */
virtio_queue_set_host_notifier_fd_handler(vq, assign, !assign); virtio_bus_stop_ioeventfd(bus);
if (!assign) {
/* Use generic ioeventfd handler again. */
k->ioeventfd_set_disabled(proxy, false);
} }
return 0; return set_host_notifier_internal(proxy, bus, n, assign, false);
} }
static char *virtio_bus_get_dev_path(DeviceState *dev) static char *virtio_bus_get_dev_path(DeviceState *dev)