Re: [Qemu-stable] [Qemu-devel] [PATCH V2] net: fix qemu_announce_self not emitting packets

[Peter Lieven]

Am 07.06.2016 um 17:28 schrieb Yang Hongyang:

On Tue, Jun 7, 2016 at 9:00 PM, Peter Lieven <address@hidden> wrote:

commit fefe2a78 accidently dropped the code path for injecting
raw packets. This feature is needed for sending gratuitous ARPs
after an incoming migration has completed. The result is increased
network downtime for vservers where the network card is not virtio-net
with the VIRTIO_NET_F_GUEST_ANNOUNCE feature.

Fixes: fefe2a78abde932e0f340b21bded2c86def1d242
Cc: address@hidden
Cc: address@hidden
Signed-off-by: Peter Lieven <address@hidden>
---
v1->v2: assert that only raw packets with a plain buffer come in. [Paolo]

 net/net.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/net/net.c b/net/net.c
index 5f3e5a9..5e1b5fa 100644
--- a/net/net.c
+++ b/net/net.c
@@ -714,6 +714,11 @@ ssize_t qemu_deliver_packet_iov(NetClientState *sender,
     NetClientState *nc = opaque;
     int ret;

+    /* we currently only support sending raw packets via qemu_send_packet_raw.
+     * If we want generic raw iov support we need to implement something like
+     * .receive_raw_iov in NetClientInfo first. */
+    assert(!(flags & QEMU_NET_PACKET_FLAG_RAW) || iovcnt == 1);
+

This assert is hard to understand IMO...I think move assert(iovcnt==1) as well as the

comment to if condition below as Paolo said previously is better...

This assert would only trigger if the NetClient implements .receive_raw. This way it could
happen that someone injects RAW packets via an other way than qemu_send_packet_raw.
But he might not see that its not allowed if he uses a backend that does not implement
sending raw packets. If then someone uses a tap backend things break again.

Peter