net/af_xdp: make reserve/submit peek/release consistent

As David pointed out, if we reserve N slots for Tx, but only submit n
slots, we would end up with an incorrect opinion of the number of available
slots later, we also would get wrong idx when we call
xsk_ring_prod__reserve next time. It also applies to
xsk_ring_cons__peek()/xsk_ring_cons__release().

This patch ensures that both reserve/submit and peek/release are
consistent.

Fixes: f1debd77efaf ("net/af_xdp: introduce AF_XDP PMD")

Suggested-by: David Marchand <david.marchand@redhat.com>
Signed-off-by: Xiaolong Ye <xiaolong.ye@intel.com>
Reviewed-by: David Marchand <david.marchand@redhat.com>

diff --git a/drivers/net/af_xdp/rte_eth_af_xdp.c b/drivers/net/af_xdp/rte_eth_af_xdp.c
index c46916b..6a00965 100644 (file)
--- a/drivers/net/af_xdp/rte_eth_af_xdp.c
+++ b/drivers/net/af_xdp/rte_eth_af_xdp.c
@@ -134,30 +134,34 @@ static const struct rte_eth_link pmd_link = {
 };
 
 static inline int
-reserve_fill_queue(struct xsk_umem_info *umem, int reserve_size)
+reserve_fill_queue(struct xsk_umem_info *umem, uint16_t reserve_size)
 {
        struct xsk_ring_prod *fq = &umem->fq;
+       void *addrs[reserve_size];
        uint32_t idx;
-       int i, ret;
+       uint16_t i;
+
+       if (rte_ring_dequeue_bulk(umem->buf_ring, addrs, reserve_size, NULL)
+                   != reserve_size) {
+               AF_XDP_LOG(DEBUG, "Failed to get enough buffers for fq.\n");
+               return -1;
+       }
 
-       ret = xsk_ring_prod__reserve(fq, reserve_size, &idx);
-       if (unlikely(!ret)) {
-               AF_XDP_LOG(ERR, "Failed to reserve enough fq descs.\n");
-               return ret;
+       if (unlikely(!xsk_ring_prod__reserve(fq, reserve_size, &idx))) {
+               AF_XDP_LOG(DEBUG, "Failed to reserve enough fq descs.\n");
+               rte_ring_enqueue_bulk(umem->buf_ring, addrs,
+                               reserve_size, NULL);
+               return -1;
        }
 
        for (i = 0; i < reserve_size; i++) {
                __u64 *fq_addr;
-               void *addr = NULL;
-               if (rte_ring_dequeue(umem->buf_ring, &addr)) {
-                       i--;
-                       break;
-               }
+
                fq_addr = xsk_ring_prod__fill_addr(fq, idx++);
-               *fq_addr = (uint64_t)addr;
+               *fq_addr = (uint64_t)addrs[i];
        }
 
-       xsk_ring_prod__submit(fq, i);
+       xsk_ring_prod__submit(fq, reserve_size);
 
        return 0;
 }
@@ -174,21 +178,20 @@ eth_af_xdp_rx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
        struct rte_mbuf *mbufs[ETH_AF_XDP_TX_BATCH_SIZE];
        unsigned long dropped = 0;
        unsigned long rx_bytes = 0;
-       uint16_t count = 0;
        int rcvd, i;
 
        nb_pkts = RTE_MIN(nb_pkts, ETH_AF_XDP_TX_BATCH_SIZE);
 
+       if (unlikely(rte_pktmbuf_alloc_bulk(rxq->mb_pool, mbufs, nb_pkts) != 0))
+               return 0;
+
        rcvd = xsk_ring_cons__peek(rx, nb_pkts, &idx_rx);
        if (rcvd == 0)
-               return 0;
+               goto out;
 
        if (xsk_prod_nb_free(fq, free_thresh) >= free_thresh)
                (void)reserve_fill_queue(umem, ETH_AF_XDP_RX_BATCH_SIZE);
 
-       if (unlikely(rte_pktmbuf_alloc_bulk(rxq->mb_pool, mbufs, rcvd) != 0))
-               return 0;
-
        for (i = 0; i < rcvd; i++) {
                const struct xdp_desc *desc;
                uint64_t addr;
@@ -204,7 +207,7 @@ eth_af_xdp_rx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
                rte_pktmbuf_pkt_len(mbufs[i]) = len;
                rte_pktmbuf_data_len(mbufs[i]) = len;
                rx_bytes += len;
-               bufs[count++] = mbufs[i];
+               bufs[i] = mbufs[i];
 
                rte_ring_enqueue(umem->buf_ring, (void *)addr);
        }
@@ -215,7 +218,12 @@ eth_af_xdp_rx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
        rxq->stats.rx_pkts += (rcvd - dropped);
        rxq->stats.rx_bytes += rx_bytes;
 
-       return count;
+out:
+       if (rcvd != nb_pkts)
+               rte_mempool_put_bulk(rxq->mb_pool, (void **)&mbufs[rcvd],
+                                    nb_pkts - rcvd);
+
+       return rcvd;
 }
 
 static void
@@ -262,7 +270,7 @@ eth_af_xdp_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
        struct rte_mbuf *mbuf;
        void *addrs[ETH_AF_XDP_TX_BATCH_SIZE];
        unsigned long tx_bytes = 0;
-       int i, valid = 0;
+       int i;
        uint32_t idx_tx;
 
        nb_pkts = RTE_MIN(nb_pkts, ETH_AF_XDP_TX_BATCH_SIZE);
@@ -283,20 +291,18 @@ eth_af_xdp_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
        for (i = 0; i < nb_pkts; i++) {
                struct xdp_desc *desc;
                void *pkt;
-               uint32_t buf_len = ETH_AF_XDP_FRAME_SIZE
-                                       - ETH_AF_XDP_DATA_HEADROOM;
+
                desc = xsk_ring_prod__tx_desc(&txq->tx, idx_tx + i);
                mbuf = bufs[i];
-               if (mbuf->pkt_len <= buf_len) {
-                       desc->addr = (uint64_t)addrs[valid];
-                       desc->len = mbuf->pkt_len;
-                       pkt = xsk_umem__get_data(umem->mz->addr,
-                                                desc->addr);
-                       rte_memcpy(pkt, rte_pktmbuf_mtod(mbuf, void *),
-                              desc->len);
-                       valid++;
-                       tx_bytes += mbuf->pkt_len;
-               }
+
+               desc->addr = (uint64_t)addrs[i];
+               desc->len = mbuf->pkt_len;
+               pkt = xsk_umem__get_data(umem->mz->addr,
+                                        desc->addr);
+               rte_memcpy(pkt, rte_pktmbuf_mtod(mbuf, void *),
+                          desc->len);
+               tx_bytes += mbuf->pkt_len;
+
                rte_pktmbuf_free(mbuf);
        }
 
@@ -304,12 +310,7 @@ eth_af_xdp_tx(void *queue, struct rte_mbuf **bufs, uint16_t nb_pkts)
 
        kick_tx(txq);
 
-       if (valid < nb_pkts)
-               rte_ring_enqueue_bulk(umem->buf_ring, &addrs[valid],
-                                nb_pkts - valid, NULL);
-
-       txq->stats.err_pkts += nb_pkts - valid;
-       txq->stats.tx_pkts += valid;
+       txq->stats.tx_pkts += nb_pkts;
        txq->stats.tx_bytes += tx_bytes;
 
        return nb_pkts;