On Thu, Aug 01, 2013 at 07:15:54PM +0200, Jan Kiszka wrote: > I was digging into the involved code and found something fishy: > > net/tap.c: > static void tap_send(void *opaque) > { > ... > size = qemu_send_packet_async(&s->nc, buf, size, > tap_send_completed); > if (size == 0) { > tap_read_poll(s, false); > } > > So, if tap_send is registered for the mainloop polling (ie. can_receive > returned true before starting to poll) but qemu_send_packet_async > returns 0 now as qemu_can_send_packet/can_receive happens to report > false in the meantime, we will disable read polling. If also write > polling is off, the fd will be completely removed from the iohandler > list. But even if write polling remains on, I wonder what should bring > read polling back?
This behavior seems fine to me. Once the peer (pcnet) is able to receive again it must flush the queue, this will re-enable tap_read_poll(). Can you explain a bit more why this would be a problem? Stefan