Message ID | 152120204902.1103.7114773412109402452.stgit@bahia.lan |
---|---|
State | New |
Headers | show |
Series | [v2] virtio_net: flush uncompleted TX on reset | expand |
On 2018年03月16日 20:07, Greg Kurz wrote: > If the backend could not transmit a packet right away for some reason, > the packet is queued for asynchronous sending. The corresponding vq > element is tracked in the async_tx.elem field of the VirtIONetQueue, > for later freeing when the transmission is complete. > > If a reset happens before completion, virtio_net_tx_complete() will push > async_tx.elem back to the guest anyway, and we end up with the inuse flag > of the vq being equal to -1. The next call to virtqueue_pop() is then > likely to fail with "Virtqueue size exceeded". > > This can be reproduced easily by starting a guest with an hubport backend > that is not connected to a functional network, eg, > > -device virtio-net-pci,netdev=hub0 -netdev hubport,id=hub0,hubid=0 > > and no other -netdev hubport,hubid=0 on the command line. > > The appropriate fix is to ensure that such an asynchronous transmission > cannot survive a device reset. So for all queues, we first try to send > the packet again, and eventually we purge it if the backend still could > not deliver it. > > Reported-by: R. Nageswara Sastry <nasastry@in.ibm.com> > Buglink: https://github.com/open-power-host-os/qemu/issues/37 > Signed-off-by: Greg Kurz <groug@kaod.org> > Tested-by: R. Nageswara Sastry <nasastry@in.ibm.com> > --- > v2: - make qemu_flush_or_purge_queued_packets() extern and use it > - reworded reproducer paragraph in changelog > --- > hw/net/virtio-net.c | 8 ++++++++ > include/net/net.h | 1 + > net/net.c | 1 - > 3 files changed, 9 insertions(+), 1 deletion(-) > > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c > index 188744e17d57..e5ed35489380 100644 > --- a/hw/net/virtio-net.c > +++ b/hw/net/virtio-net.c > @@ -422,6 +422,7 @@ static RxFilterInfo *virtio_net_query_rxfilter(NetClientState *nc) > static void virtio_net_reset(VirtIODevice *vdev) > { > VirtIONet *n = VIRTIO_NET(vdev); > + int i; > > /* Reset back to compatibility mode */ > n->promisc = 1; > @@ -445,6 +446,13 @@ static void virtio_net_reset(VirtIODevice *vdev) > memcpy(&n->mac[0], &n->nic->conf->macaddr, sizeof(n->mac)); > qemu_format_nic_info_str(qemu_get_queue(n->nic), n->mac); > memset(n->vlans, 0, MAX_VLAN >> 3); > + > + /* Flush any async TX */ > + for (i = 0; i < n->max_queues; i++) { > + NetClientState *nc = qemu_get_subqueue(n->nic, i); > + qemu_flush_or_purge_queued_packets(nc->peer, true); > + assert(!virtio_net_get_subqueue(nc)->async_tx.elem); > + } > } > > static void peer_test_vnet_hdr(VirtIONet *n) > diff --git a/include/net/net.h b/include/net/net.h > index a943e968a3dc..1f7341e4592b 100644 > --- a/include/net/net.h > +++ b/include/net/net.h > @@ -153,6 +153,7 @@ ssize_t qemu_send_packet_async(NetClientState *nc, const uint8_t *buf, > int size, NetPacketSent *sent_cb); > void qemu_purge_queued_packets(NetClientState *nc); > void qemu_flush_queued_packets(NetClientState *nc); > +void qemu_flush_or_purge_queued_packets(NetClientState *nc, bool purge); > void qemu_format_nic_info_str(NetClientState *nc, uint8_t macaddr[6]); > bool qemu_has_ufo(NetClientState *nc); > bool qemu_has_vnet_hdr(NetClientState *nc); > diff --git a/net/net.c b/net/net.c > index 5222e450698c..29f83983e55d 100644 > --- a/net/net.c > +++ b/net/net.c > @@ -595,7 +595,6 @@ void qemu_purge_queued_packets(NetClientState *nc) > qemu_net_queue_purge(nc->peer->incoming_queue, nc); > } > > -static > void qemu_flush_or_purge_queued_packets(NetClientState *nc, bool purge) > { > nc->receive_disabled = 0; > > Applied and queued for -stable. Thanks
>> -static >> void qemu_flush_or_purge_queued_packets(NetClientState *nc, bool >> purge) >> { >> nc->receive_disabled = 0; >> >> > > Applied and queued for -stable. > > Thanks > Unfortunately, this breaks hotplug test: TEST: tests/virtio-net-test... (pid=7117) /x86_64/virtio/net/pci/basic: OK /x86_64/virtio/net/pci/rx_stop_cont: OK /x86_64/virtio/net/pci/hotplug: Broken pipe FAIL Thanks
On Tue, 20 Mar 2018 11:27:26 +0800 Jason Wang <jasowang@redhat.com> wrote: > >> -static > >> void qemu_flush_or_purge_queued_packets(NetClientState *nc, bool > >> purge) > >> { > >> nc->receive_disabled = 0; > >> > >> > > > > Applied and queued for -stable. > > > > Thanks > > > > Unfortunately, this breaks hotplug test: > > TEST: tests/virtio-net-test... (pid=7117) > /x86_64/virtio/net/pci/basic: OK > /x86_64/virtio/net/pci/rx_stop_cont: OK > /x86_64/virtio/net/pci/hotplug: Broken pipe > FAIL > > Thanks Hi Jason, Yes, I've just realized this patch assumes the virtio-net device does have an associated backend (ie, nc->peer != NULL) otherwise we segfault. This happens to be the case with the hotplug test. I'll send a v3. Cheers, -- Greg
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index 188744e17d57..e5ed35489380 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -422,6 +422,7 @@ static RxFilterInfo *virtio_net_query_rxfilter(NetClientState *nc) static void virtio_net_reset(VirtIODevice *vdev) { VirtIONet *n = VIRTIO_NET(vdev); + int i; /* Reset back to compatibility mode */ n->promisc = 1; @@ -445,6 +446,13 @@ static void virtio_net_reset(VirtIODevice *vdev) memcpy(&n->mac[0], &n->nic->conf->macaddr, sizeof(n->mac)); qemu_format_nic_info_str(qemu_get_queue(n->nic), n->mac); memset(n->vlans, 0, MAX_VLAN >> 3); + + /* Flush any async TX */ + for (i = 0; i < n->max_queues; i++) { + NetClientState *nc = qemu_get_subqueue(n->nic, i); + qemu_flush_or_purge_queued_packets(nc->peer, true); + assert(!virtio_net_get_subqueue(nc)->async_tx.elem); + } } static void peer_test_vnet_hdr(VirtIONet *n) diff --git a/include/net/net.h b/include/net/net.h index a943e968a3dc..1f7341e4592b 100644 --- a/include/net/net.h +++ b/include/net/net.h @@ -153,6 +153,7 @@ ssize_t qemu_send_packet_async(NetClientState *nc, const uint8_t *buf, int size, NetPacketSent *sent_cb); void qemu_purge_queued_packets(NetClientState *nc); void qemu_flush_queued_packets(NetClientState *nc); +void qemu_flush_or_purge_queued_packets(NetClientState *nc, bool purge); void qemu_format_nic_info_str(NetClientState *nc, uint8_t macaddr[6]); bool qemu_has_ufo(NetClientState *nc); bool qemu_has_vnet_hdr(NetClientState *nc); diff --git a/net/net.c b/net/net.c index 5222e450698c..29f83983e55d 100644 --- a/net/net.c +++ b/net/net.c @@ -595,7 +595,6 @@ void qemu_purge_queued_packets(NetClientState *nc) qemu_net_queue_purge(nc->peer->incoming_queue, nc); } -static void qemu_flush_or_purge_queued_packets(NetClientState *nc, bool purge) { nc->receive_disabled = 0;