On Wed, Oct 06, 2010 at 12:13:35PM -0500, Anthony Liguori wrote:
> On 10/06/2010 11:58 AM, Michael S. Tsirkin wrote:
> >On Wed, Oct 06, 2010 at 11:35:08AM -0500, Anthony Liguori wrote:
> >>On 10/06/2010 11:04 AM, Michael S. Tsirkin wrote:
> >>>With -netdev, virtio devices present offload
> >>>features to guest, depending on the backend used.
> >>>Thus, removing host netdev peer while guest is
> >>>active leads to guest-visible inconsistency and/or crashes.
> >>>
> >>>As a solution, while guest (NIC) peer device exists,
> >>>we prevent the host peer from being deleted.
> >>>This patch does this by adding peer_deleted flag in nic state:
> >>>if host device is going away while guest device
> >>>is around, set this flag and keep a shell of
> >>>the host device around for as long as guest device exists.
> >>>
> >>>The link is put down so all packets will get discarded.
> >>>
> >>>At the moment, management can detect that device deletion
> >>>is delayed by doing info net. As a next step, we shall add
> >>>commands that control hotplug/unplug without
> >>>removing the device, and an event to report that
> >>>guest has responded to the hotplug event.
> >>>
> >>>Signed-off-by: Michael S. Tsirkin<m...@redhat.com>
> >>I don't think this is a very good idea. Making netdev_del
> >>conditionally succeed is going to break management tools and is very
> >>non-intuitive.
> >>
> >>Regards,
> >>
> >>Anthony Liguori
> >But this is not what this does. With this patch netdev_del always
> >succeeds, and clears the device state leaving just an empty shell around.
> >The shell goes away together with the NIC.
>
> Sorry, I confused myself. I'm a little confused by the statement:
>
> "At the moment, management can detect that device deletion is delayed by
> doing info net."
>
> Is this still the case since you remove the netdev from the list?
>
> Regards,
>
> Anthony Liguori
The device in question here is the PCI device removed with device_del.
The unplug there is asynchronous and I did not change this.
>
> >>>---
> >>>
> >>> Changes from v3:
> >>> make sure ->cleanup is called for NICs
> >>> Changes from v2:
> >>> fix crash on repeated netdev_del
> >>>
> >>> net.c | 49 ++++++++++++++++++++++++++++++++++++++++++-------
> >>> net.h | 1 +
> >>> 2 files changed, 43 insertions(+), 7 deletions(-)
> >>>
> >>>diff --git a/net.c b/net.c
> >>>index 3d0fde7..ed74c7f 100644
> >>>--- a/net.c
> >>>+++ b/net.c
> >>>@@ -281,29 +281,64 @@ NICState *qemu_new_nic(NetClientInfo *info,
> >>> return nic;
> >>> }
> >>>
> >>>-void qemu_del_vlan_client(VLANClientState *vc)
> >>>+static void qemu_cleanup_vlan_client(VLANClientState *vc)
> >>> {
> >>> if (vc->vlan) {
> >>> QTAILQ_REMOVE(&vc->vlan->clients, vc, next);
> >>> } else {
> >>>- if (vc->send_queue) {
> >>>- qemu_del_net_queue(vc->send_queue);
> >>>- }
> >>> QTAILQ_REMOVE(&non_vlan_clients, vc, next);
> >>>- if (vc->peer) {
> >>>- vc->peer->peer = NULL;
> >>>- }
> >>> }
> >>>
> >>> if (vc->info->cleanup) {
> >>> vc->info->cleanup(vc);
> >>> }
> >>>+}
> >>>
> >>>+static void qemu_free_vlan_client(VLANClientState *vc)
> >>>+{
> >>>+ if (!vc->vlan) {
> >>>+ if (vc->send_queue) {
> >>>+ qemu_del_net_queue(vc->send_queue);
> >>>+ }
> >>>+ if (vc->peer) {
> >>>+ vc->peer->peer = NULL;
> >>>+ }
> >>>+ }
> >>> qemu_free(vc->name);
> >>> qemu_free(vc->model);
> >>> qemu_free(vc);
> >>> }
> >>>
> >>>+void qemu_del_vlan_client(VLANClientState *vc)
> >>>+{
> >>>+ /* If there is a peer NIC, delete and cleanup client, but do not
> >>>free. */
> >>>+ if (!vc->vlan&& vc->peer&& vc->peer->info->type ==
> >>>NET_CLIENT_TYPE_NIC) {
> >>>+ NICState *nic = DO_UPCAST(NICState, nc, vc->peer);
> >>>+ if (nic->peer_deleted) {
> >>>+ return;
> >>>+ }
> >>>+ nic->peer_deleted = true;
> >>>+ /* Let NIC know peer is gone. */
> >>>+ vc->peer->link_down = true;
> >>>+ if (vc->peer->info->link_status_changed) {
> >>>+ vc->peer->info->link_status_changed(vc->peer);
> >>>+ }
> >>>+ qemu_cleanup_vlan_client(vc);
> >>>+ return;
> >>>+ }
> >>>+
> >>>+ /* If this is a peer NIC and peer has already been deleted, free it
> >>>now. */
> >>>+ if (!vc->vlan&& vc->peer&& vc->info->type == NET_CLIENT_TYPE_NIC)
> >>>{
> >>>+ NICState *nic = DO_UPCAST(NICState, nc, vc);
> >>>+ if (nic->peer_deleted) {
> >>>+ qemu_free_vlan_client(vc->peer);
> >>>+ }
> >>>+ }
> >>>+
> >>>+ qemu_cleanup_vlan_client(vc);
> >>>+ qemu_free_vlan_client(vc);
> >>>+}
> >>>+
> >>> VLANClientState *
> >>> qemu_find_vlan_client_by_name(Monitor *mon, int vlan_id,
> >>> const char *client_str)
> >>>diff --git a/net.h b/net.h
> >>>index 518cf9c..44c31a9 100644
> >>>--- a/net.h
> >>>+++ b/net.h
> >>>@@ -72,6 +72,7 @@ typedef struct NICState {
> >>> VLANClientState nc;
> >>> NICConf *conf;
> >>> void *opaque;
> >>>+ bool peer_deleted;
> >>> } NICState;
> >>>
> >>> struct VLANState {
