qemu/net/netmap.c

161     struct netmap_ring *ring = s->tx;
162     unsigned int tail = ring->tail;
170     last = i = ring->head;
172     if (nm_ring_space(ring) < iovcnt) {
176          * (e.g., we don't advance ring->head). */
177         ring->cur = tail;
192             nm_frag_size = MIN(iov_frag_size, ring->nr_buf_size);
197                 ring->cur = tail;
202             idx = ring->slot[i].buf_idx;
203             dst = (uint8_t *)NETMAP_BUF(ring, idx);
205             ring->slot[i].len = nm_frag_size;
206             ring->slot[i].flags = NS_MOREFRAG;
210             i = nm_ring_next(ring, i);
217     ring->slot[last].flags &= ~NS_MOREFRAG;
219     /* Now update ring->head and ring->cur to publish the new slots and
221     ring->head = ring->cur = i;
251     struct netmap_ring *ring = s->rx;
252     unsigned int tail = ring->tail;
255        RX ring and the forwarding path towards the peer is open. */
256     while (ring->head != tail) {
257         uint32_t i = ring->head;
265             idx = ring->slot[i].buf_idx;
266             morefrag = (ring->slot[i].flags & NS_MOREFRAG);
267             s->iov[iovcnt].iov_base = (void *)NETMAP_BUF(ring, idx);
268             s->iov[iovcnt].iov_len = ring->slot[i].len;
270             i = nm_ring_next(ring, i);
273         /* Advance ring->cur to tell the kernel that we have seen the slots. */
274         ring->cur = i;
278              * incomplete slots by updating ring->head. We will hopefully
287         ring->head = i;