On Mon, Sep 07, 2015 at 03:37:20PM +0800, Yang Hongyang wrote:
Hi Stefan,
On 09/04/2015 06:32 PM, Stefan Hajnoczi wrote:
[...]
net/queue.c has logic to send/queue/flush packets but a
qemu_deliver_packet() call is hardcoded.
Maybe you can extend qemu_new_net_queue() like this:
/* Returns:
* >0 - success
* 0 - queue packet for future redelivery
* <0 - failure (discard packet)
*/
typedef ssize_t NetQueueDeliverFunc(NetClientState *sender,
unsigned flags,
const struct iovec *iov,
int iovcnt,
void *opaque);
NetQueue *qemu_new_net_queue(NetQueueDeliverFunc deliver,
void *opaque);
Now net/net.c:qemu_net_client_setup() needs to call:
nc->incoming_queue = qemu_new_net_queue(qemu_deliver_packet_iov, nc);
And the filter code can use qemu_net_queue_send_iov() and
qemu_net_queue_flush(). The filter just needs to provide its own
NetQueueDeliveryFunc.
I haven't checked the details (e.g. non-iov delivery, etc) but the idea
is to use the net/queue.c API instead of duplicating similar logic in
the filter code.
Thanks very much for the suggestion, I've already implemented it and tested,
the code looks cleaner now.
The last issue is the QOM thing, do Markus and Andreas have more input
about that?
If you would like to see examples of QOM usage, take a look at
iothread.c and/or backends/hostmem.c.
The key things are:
1. They use include/qom/object.h to register a type based on
TYPE_OBJECT and their properties are registered using
object_property_add_*().
2. They implement the TYPE_USER_CREATABLE interface so the -object
command-line option can be used to instantiate them. See
object_interfaces.h.
As a result, a lot of code becomes unnecessary and iothread.c, in
particular, is quite short.