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?
>
>> ---
>>
>> 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
