+/**
+ * DPDK callback for RX with scattered packets support.
+ *
+ * @param dpdk_rxq
+ * Generic pointer to RX queue structure.
+ * @param[out] pkts
+ * Array to store received packets.
+ * @param pkts_n
+ * Maximum number of packets in array.
+ *
+ * @return
+ * Number of packets successfully received (<= pkts_n).
+ */
+uint16_t
+mlx5_rx_burst_sp(void *dpdk_rxq, struct rte_mbuf **pkts, uint16_t pkts_n)
+{
+ struct rxq *rxq = (struct rxq *)dpdk_rxq;
+ struct rxq_elt_sp (*elts)[rxq->elts_n] = rxq->elts.sp;
+ const unsigned int elts_n = rxq->elts_n;
+ unsigned int elts_head = rxq->elts_head;
+ struct ibv_recv_wr head;
+ struct ibv_recv_wr **next = &head.next;
+ struct ibv_recv_wr *bad_wr;
+ unsigned int i;
+ unsigned int pkts_ret = 0;
+ int ret;
+
+ if (unlikely(!rxq->sp))
+ return mlx5_rx_burst(dpdk_rxq, pkts, pkts_n);
+ if (unlikely(elts == NULL)) /* See RTE_DEV_CMD_SET_MTU. */
+ return 0;
+ for (i = 0; (i != pkts_n); ++i) {
+ struct rxq_elt_sp *elt = &(*elts)[elts_head];
+ struct ibv_recv_wr *wr = &elt->wr;
+ uint64_t wr_id = wr->wr_id;
+ unsigned int len;
+ unsigned int pkt_buf_len;
+ struct rte_mbuf *pkt_buf = NULL; /* Buffer returned in pkts. */
+ struct rte_mbuf **pkt_buf_next = &pkt_buf;
+ unsigned int seg_headroom = RTE_PKTMBUF_HEADROOM;
+ unsigned int j = 0;
+ uint32_t flags;
+
+ /* Sanity checks. */
+#ifdef NDEBUG
+ (void)wr_id;
+#endif
+ assert(wr_id < rxq->elts_n);
+ assert(wr->sg_list == elt->sges);
+ assert(wr->num_sge == RTE_DIM(elt->sges));
+ assert(elts_head < rxq->elts_n);
+ assert(rxq->elts_head < rxq->elts_n);
+ ret = rxq->if_cq->poll_length_flags(rxq->cq, NULL, NULL,
+ &flags);
+ if (unlikely(ret < 0)) {
+ struct ibv_wc wc;
+ int wcs_n;
+
+ DEBUG("rxq=%p, poll_length() failed (ret=%d)",
+ (void *)rxq, ret);
+ /* ibv_poll_cq() must be used in case of failure. */
+ wcs_n = ibv_poll_cq(rxq->cq, 1, &wc);
+ if (unlikely(wcs_n == 0))
+ break;
+ if (unlikely(wcs_n < 0)) {
+ DEBUG("rxq=%p, ibv_poll_cq() failed (wcs_n=%d)",
+ (void *)rxq, wcs_n);
+ break;
+ }
+ assert(wcs_n == 1);
+ if (unlikely(wc.status != IBV_WC_SUCCESS)) {
+ /* Whatever, just repost the offending WR. */
+ DEBUG("rxq=%p, wr_id=%" PRIu64 ": bad work"
+ " completion status (%d): %s",
+ (void *)rxq, wc.wr_id, wc.status,
+ ibv_wc_status_str(wc.status));
+ /* Link completed WRs together for repost. */
+ *next = wr;
+ next = &wr->next;
+ goto repost;
+ }
+ ret = wc.byte_len;
+ }
+ if (ret == 0)
+ break;
+ len = ret;
+ pkt_buf_len = len;
+ /* Link completed WRs together for repost. */
+ *next = wr;
+ next = &wr->next;
+ /*
+ * Replace spent segments with new ones, concatenate and
+ * return them as pkt_buf.
+ */
+ while (1) {
+ struct ibv_sge *sge = &elt->sges[j];
+ struct rte_mbuf *seg = elt->bufs[j];
+ struct rte_mbuf *rep;
+ unsigned int seg_tailroom;
+
+ /*
+ * Fetch initial bytes of packet descriptor into a
+ * cacheline while allocating rep.
+ */
+ rte_prefetch0(seg);
+ rep = __rte_mbuf_raw_alloc(rxq->mp);
+ if (unlikely(rep == NULL)) {
+ /*
+ * Unable to allocate a replacement mbuf,
+ * repost WR.
+ */
+ DEBUG("rxq=%p, wr_id=%" PRIu64 ":"
+ " can't allocate a new mbuf",
+ (void *)rxq, wr_id);
+ if (pkt_buf != NULL) {
+ *pkt_buf_next = NULL;
+ rte_pktmbuf_free(pkt_buf);
+ }
+ /* Increment out of memory counters. */
+ ++rxq->priv->dev->data->rx_mbuf_alloc_failed;
+ goto repost;
+ }
+#ifndef NDEBUG
+ /* Poison user-modifiable fields in rep. */
+ NEXT(rep) = (void *)((uintptr_t)-1);
+ SET_DATA_OFF(rep, 0xdead);
+ DATA_LEN(rep) = 0xd00d;
+ PKT_LEN(rep) = 0xdeadd00d;
+ NB_SEGS(rep) = 0x2a;
+ PORT(rep) = 0x2a;
+ rep->ol_flags = -1;
+#endif
+ assert(rep->buf_len == seg->buf_len);
+ assert(rep->buf_len == rxq->mb_len);
+ /* Reconfigure sge to use rep instead of seg. */
+ assert(sge->lkey == rxq->mr->lkey);
+ sge->addr = ((uintptr_t)rep->buf_addr + seg_headroom);
+ elt->bufs[j] = rep;
+ ++j;
+ /* Update pkt_buf if it's the first segment, or link
+ * seg to the previous one and update pkt_buf_next. */
+ *pkt_buf_next = seg;
+ pkt_buf_next = &NEXT(seg);
+ /* Update seg information. */
+ seg_tailroom = (seg->buf_len - seg_headroom);
+ assert(sge->length == seg_tailroom);
+ SET_DATA_OFF(seg, seg_headroom);
+ if (likely(len <= seg_tailroom)) {
+ /* Last segment. */
+ DATA_LEN(seg) = len;
+ PKT_LEN(seg) = len;
+ /* Sanity check. */
+ assert(rte_pktmbuf_headroom(seg) ==
+ seg_headroom);
+ assert(rte_pktmbuf_tailroom(seg) ==
+ (seg_tailroom - len));
+ break;
+ }
+ DATA_LEN(seg) = seg_tailroom;
+ PKT_LEN(seg) = seg_tailroom;
+ /* Sanity check. */
+ assert(rte_pktmbuf_headroom(seg) == seg_headroom);
+ assert(rte_pktmbuf_tailroom(seg) == 0);
+ /* Fix len and clear headroom for next segments. */
+ len -= seg_tailroom;
+ seg_headroom = 0;
+ }
+ /* Update head and tail segments. */
+ *pkt_buf_next = NULL;
+ assert(pkt_buf != NULL);
+ assert(j != 0);
+ NB_SEGS(pkt_buf) = j;
+ PORT(pkt_buf) = rxq->port_id;
+ PKT_LEN(pkt_buf) = pkt_buf_len;
+
+ /* Return packet. */
+ *(pkts++) = pkt_buf;
+ ++pkts_ret;
+repost:
+ if (++elts_head >= elts_n)
+ elts_head = 0;
+ continue;
+ }
+ if (unlikely(i == 0))
+ return 0;
+ *next = NULL;
+ /* Repost WRs. */
+#ifdef DEBUG_RECV
+ DEBUG("%p: reposting %d WRs", (void *)rxq, i);
+#endif
+ ret = ibv_post_recv(rxq->qp, head.next, &bad_wr);
+ if (unlikely(ret)) {
+ /* Inability to repost WRs is fatal. */
+ DEBUG("%p: ibv_post_recv(): failed for WR %p: %s",
+ (void *)rxq->priv,
+ (void *)bad_wr,
+ strerror(ret));
+ abort();
+ }
+ rxq->elts_head = elts_head;
+ return pkts_ret;
+}
+