Commit cc599ed6 authored by Vincenzo Maffione's avatar Vincenzo Maffione Committed by Jason Wang
Browse files

net: netmap: small improvements netmap_send() 



This change improves the handling of incomplete multi-slot packets
(e.g. with the NS_MOREFRAG set), by advancing ring->head only on
complete packets. The ring->cur pointer is advanced in any case in
order to acknowledge the kernel and move the wake-up point (thus
avoiding repeated wake-ups).
Also don't be verbose when incomplete packets are found.

Signed-off-by: default avatarVincenzo Maffione <v.maffione@gmail.com>
Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
parent 6d3aaa5b

net/netmap.c

+19 −12
Original line number Diff line number Diff line
@@ -272,39 +272,46 @@ static void netmap_send(void *opaque) 
{

    NetmapState *s = opaque;

    struct netmap_ring *ring = s->rx;

    unsigned int tail = ring->tail;



    /* Keep sending while there are available packets into the netmap

    /* Keep sending while there are available slots in the netmap

       RX ring and the forwarding path towards the peer is open. */

    while (!nm_ring_empty(ring)) {

        uint32_t i;

    while (ring->head != tail) {

        uint32_t i = ring->head;

        uint32_t idx;

        bool morefrag;

        int iovcnt = 0;

        int iovsize;



        /* Get a (possibly multi-slot) packet. */

        do {

            i = ring->cur;

            idx = ring->slot[i].buf_idx;

            morefrag = (ring->slot[i].flags & NS_MOREFRAG);

            s->iov[iovcnt].iov_base = (u_char *)NETMAP_BUF(ring, idx);

            s->iov[iovcnt].iov_base = (void *)NETMAP_BUF(ring, idx);

            s->iov[iovcnt].iov_len = ring->slot[i].len;

            iovcnt++;

            i = nm_ring_next(ring, i);

        } while (i != tail && morefrag);



            ring->cur = ring->head = nm_ring_next(ring, i);

        } while (!nm_ring_empty(ring) && morefrag);

        /* Advance ring->cur to tell the kernel that we have seen the slots. */

        ring->cur = i;



        if (unlikely(nm_ring_empty(ring) && morefrag)) {

            RD(5, "[netmap_send] ran out of slots, with a pending"

                   "incomplete packet\n");

        if (unlikely(morefrag)) {

            /* This is a truncated packet, so we can stop without releasing the

             * incomplete slots by updating ring->head. We will hopefully

             * re-read the complete packet the next time we are called. */

            break;

        }



        iovsize = qemu_sendv_packet_async(&s->nc, s->iov, iovcnt,

                                            netmap_send_completed);



        /* Release the slots to the kernel. */

        ring->head = i;



        if (iovsize == 0) {

            /* The peer does not receive anymore. Packet is queued, stop

             * reading from the backend until netmap_send_completed()

             */

             * reading from the backend until netmap_send_completed(). */

            netmap_read_poll(s, false);

            break;

        }