On Thu, Sep 04, 2014 at 12:55:38PM +0800, Jason Wang wrote:
> On 09/02/2014 10:23 PM, Stefan Hajnoczi wrote:
> > Do not modify guest memory or devices when the guest is stopped.
> > Currently the netdevs still send packets while the guest is stopped if
> > their file descriptor was being monitored for write (e.g. the socket
> > write buffer filled before the guest was stopped).
> >
> > Netdevs call qemu_flush_queued_packets() when the file descriptor
> > becomes writable again. Don't resume packet processing when this
> > happens.
> >
> > Instead we flush queues when the guest resumes.
> >
> > Cc: qemu-sta...@nongnu.org
> > Reported-by: Michael S. Tsirkin <m...@redhat.com>
> > Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
> > ---
> > Note this fixes the transmit side. The receive side was recently fixed in
> > "net: Forbid dealing with packets when VM is not running".
> >
> > net/net.c | 30 ++++++++++++++++++++++++++++++
> > 1 file changed, 30 insertions(+)
> >
> > diff --git a/net/net.c b/net/net.c
> > index 6d930ea..74ec07a 100644
> > --- a/net/net.c
> > +++ b/net/net.c
> > @@ -47,6 +47,7 @@
> > # define CONFIG_NET_BRIDGE
> > #endif
> >
> > +static VMChangeStateEntry *net_change_state_entry;
> > static QTAILQ_HEAD(, NetClientState) net_clients;
> >
> > const char *host_net_devices[] = {
> > @@ -506,6 +507,11 @@ void qemu_purge_queued_packets(NetClientState *nc)
> >
> > void qemu_flush_queued_packets(NetClientState *nc)
> > {
> > + /* Guest memory and devices must not be modified while stopped */
> > + if (!runstate_is_running()) {
> > + return;
> > + }
> > +
>
> Consider migration case, this will prevent
> sent_cb(virtio_net_tx_complete) from being called at source. Since we
> don't migrate queue and async_tx. This may lead a interrupt lost in
> destination after migration?
>
> (Looks like virtio_net is the only user that uses async sending, not
> sure why this is needed)
Good point, I noticed this too.
Sorry about missing this the first time around.
