On Tue, 07/07 12:10, Michael S. Tsirkin wrote:
> On Tue, Jul 07, 2015 at 04:58:29PM +0800, Jason Wang wrote:
> >
> >
> > On 07/07/2015 04:13 PM, Michael S. Tsirkin wrote:
> > > On Tue, Jul 07, 2015 at 09:21:07AM +0800, Fam Zheng wrote:
> > >> Since commit 6e99c63 "net/socket: Drop net_socket_can_send" and friends,
> > >> net queues need to be explicitly flushed after qemu_can_send_packet()
> > >> returns false, because the netdev side will disable the polling of fd.
> > >>
> > >> This fixes the case of "cont" after "stop" (or migration).
> > >>
> > >> Signed-off-by: Fam Zheng <f...@redhat.com>
> > > Note virtio has its own handler which must be used to
> > > flush packets - this one might run too early or too late.
> >
> > If runs too realy (DRIVER_OK is not set), then: packet will be dropped
> > (if this patch is used with "drop virtio_net_can_receive()", or the
> > queue will be purged since qemu_can_send_packet() returns false. If too
> > late, at least tap read poll will be enabled. So still looks ok?
>
> It's still not helpful for virtio. So which cards are fixed?
>
> I just find the comment
> This fixes the case of "cont" after "stop" (or migration)
> too vague.
> Can you please include the info about what's broken in the commit log?
It does fix virtio-net, as well as most other cards. HMP "stop" then "cont"
breaks net, tested with host pinging guest while doing it.
Fam
>
> > >
> > >> ---
> > >>
> > >> v2: Unify with VM stop handler. (Stefan)
> > >> ---
> > >> net/net.c | 19 ++++++++++++-------
> > >> 1 file changed, 12 insertions(+), 7 deletions(-)
> > >>
> > >> diff --git a/net/net.c b/net/net.c
> > >> index 6ff7fec..28a5597 100644
> > >> --- a/net/net.c
> > >> +++ b/net/net.c
> > >> @@ -1257,14 +1257,19 @@ void qmp_set_link(const char *name, bool up,
> > >> Error **errp)
> > >> static void net_vm_change_state_handler(void *opaque, int running,
> > >> RunState state)
> > >> {
> > >> - /* Complete all queued packets, to guarantee we don't modify
> > >> - * state later when VM is not running.
> > >> - */
> > >> - if (!running) {
> > >> - NetClientState *nc;
> > >> - NetClientState *tmp;
> > >> + NetClientState *nc;
> > >> + NetClientState *tmp;
> > >>
> > >> - QTAILQ_FOREACH_SAFE(nc, &net_clients, next, tmp) {
> > >> + QTAILQ_FOREACH_SAFE(nc, &net_clients, next, tmp) {
> > >> + if (running) {
> > >> + /* Flush queued packets and wake up backends. */
> > >> + if (nc->peer && qemu_can_send_packet(nc)) {
> > >> + qemu_flush_queued_packets(nc->peer);
> > >> + }
> > >> + } else {
> > >> + /* Complete all queued packets, to guarantee we don't modify
> > >> + * state later when VM is not running.
> > >> + */
> > >> qemu_flush_or_purge_queued_packets(nc, true);
> > >> }
> > >> }
> > >> --
> > >> 2.4.3
