Re: [Qemu-devel] [PATCH 0/3] net: fix hub control flow (again)

[Stefan Hajnoczi <stefanha@gmail.com>]

On Fri, Aug 24, 2012 at 02:39:50PM +0100, Stefan Hajnoczi wrote:
> Two networking issues have been observed:
> 
> 1. When the USB network interface and dump net client are on the same "VLAN",
>    the USB network interface drops packets.  This was assumed to be because the
>    dump net client can receive packets all the time, whereas the USB network
>    interface has a single buffer that the guest must empty.
> 
> The (incorrect) fix for #1 was to only broadcast "VLAN" packets when all net
> clients can receive.  Once this code change was merged a new issue appeared:
> 
> 2. When two NICs are on a "VLAN" they must both be up.  If one NIC is not up
>    then no traffic can flow on the "VLAN".
> 
> This patch series fixes the root cause for #1, namely, that the USB network
> interface clobbers its input buffer when usbnet_receive() is called before the guest has a chance to empty the buffer.
> 
> Then we can revert the "VLAN" flow control change which caused #2.  The result
> is that both #1 and #2 are now fixed.
> 
> Stefan Hajnoczi (3):
>   net: clean up usbnet_receive()
>   net: fix usbnet_receive() packet drops
>   net: broadcast hub packets if at least one port can receive
> 
>  hw/usb/dev-network.c |   49 +++++++++++++++++++++++++++++++++----------------
>  net/hub.c            |    6 +++---
>  2 files changed, 36 insertions(+), 19 deletions(-)
> 
> -- 
> 1.7.10.4
> 
> 

Applied to the net tree:
https://github.com/stefanha/qemu/commits/net

Stefan