net/mlx4: simplify Rx buffer handling

Thanks to the fact the PMD temporarily uses a slower interface for Rx,
removing the WR ID hack to instead store mbuf pointers directly makes the
code simpler at no extra cost.

Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>

diff --git a/drivers/net/mlx4/mlx4.c b/drivers/net/mlx4/mlx4.c
index 79fb666..1208e7a 100644 (file)
--- a/drivers/net/mlx4/mlx4.c
+++ b/drivers/net/mlx4/mlx4.c
@@ -84,17 +84,6 @@
 #define NB_SEGS(m) ((m)->nb_segs)
 #define PORT(m) ((m)->port)
 
-/* Work Request ID data type (64 bit). */
-typedef union {
-       struct {
-               uint32_t id;
-               uint16_t offset;
-       } data;
-       uint64_t raw;
-} wr_id_t;
-
-#define WR_ID(o) (((wr_id_t *)&(o))->data)
-
 /** Configuration structure for device arguments. */
 struct mlx4_conf {
        struct {
@@ -1403,13 +1392,7 @@ rxq_alloc_elts(struct rxq *rxq, unsigned int elts_n)
                        ret = ENOMEM;
                        goto error;
                }
-               /* Configure WR. Work request ID contains its own index in
-                * the elts array and the offset between SGE buffer header and
-                * its data. */
-               WR_ID(wr->wr_id).id = i;
-               WR_ID(wr->wr_id).offset =
-                       (((uintptr_t)buf->buf_addr + RTE_PKTMBUF_HEADROOM) -
-                        (uintptr_t)buf);
+               elt->buf = buf;
                wr->next = &(*elts)[(i + 1)].wr;
                wr->sg_list = sge;
                wr->num_sge = 1;
@@ -1427,18 +1410,6 @@ rxq_alloc_elts(struct rxq *rxq, unsigned int elts_n)
                sge->lkey = rxq->mr->lkey;
                /* Redundant check for tailroom. */
                assert(sge->length == rte_pktmbuf_tailroom(buf));
-               /* Make sure elts index and SGE mbuf pointer can be deduced
-                * from WR ID. */
-               if ((WR_ID(wr->wr_id).id != i) ||
-                   ((void *)((uintptr_t)sge->addr -
-                       WR_ID(wr->wr_id).offset) != buf)) {
-                       ERROR("%p: cannot store index and offset in WR ID",
-                             (void *)rxq);
-                       sge->addr = 0;
-                       rte_pktmbuf_free(buf);
-                       ret = EOVERFLOW;
-                       goto error;
-               }
        }
        /* The last WR pointer must be NULL. */
        (*elts)[(i - 1)].wr.next = NULL;
@@ -1451,17 +1422,8 @@ rxq_alloc_elts(struct rxq *rxq, unsigned int elts_n)
        return 0;
 error:
        if (elts != NULL) {
-               for (i = 0; (i != elemof(*elts)); ++i) {
-                       struct rxq_elt *elt = &(*elts)[i];
-                       struct rte_mbuf *buf;
-
-                       if (elt->sge.addr == 0)
-                               continue;
-                       assert(WR_ID(elt->wr.wr_id).id == i);
-                       buf = (void *)((uintptr_t)elt->sge.addr -
-                               WR_ID(elt->wr.wr_id).offset);
-                       rte_pktmbuf_free_seg(buf);
-               }
+               for (i = 0; (i != elemof(*elts)); ++i)
+                       rte_pktmbuf_free_seg((*elts)[i].buf);
                rte_free(elts);
        }
        DEBUG("%p: failed, freed everything", (void *)rxq);
@@ -1487,17 +1449,8 @@ rxq_free_elts(struct rxq *rxq)
        rxq->elts = NULL;
        if (elts == NULL)
                return;
-       for (i = 0; (i != elemof(*elts)); ++i) {
-               struct rxq_elt *elt = &(*elts)[i];
-               struct rte_mbuf *buf;
-
-               if (elt->sge.addr == 0)
-                       continue;
-               assert(WR_ID(elt->wr.wr_id).id == i);
-               buf = (void *)((uintptr_t)elt->sge.addr -
-                       WR_ID(elt->wr.wr_id).offset);
-               rte_pktmbuf_free_seg(buf);
-       }
+       for (i = 0; (i != elemof(*elts)); ++i)
+               rte_pktmbuf_free_seg((*elts)[i].buf);
        rte_free(elts);
 }
 
@@ -1674,15 +1627,11 @@ mlx4_rx_burst(void *dpdk_rxq, struct rte_mbuf **pkts, uint16_t pkts_n)
                struct ibv_wc *wc = &wcs[i];
                struct rxq_elt *elt = &(*elts)[elts_head];
                struct ibv_recv_wr *wr = &elt->wr;
-               uint64_t wr_id = wr->wr_id;
                uint32_t len = wc->byte_len;
-               struct rte_mbuf *seg = (void *)((uintptr_t)elt->sge.addr -
-                       WR_ID(wr_id).offset);
+               struct rte_mbuf *seg = elt->buf;
                struct rte_mbuf *rep;
 
                /* Sanity checks. */
-               assert(WR_ID(wr_id).id < rxq->elts_n);
-               assert(wr_id == wc->wr_id);
                assert(wr->sg_list == &elt->sge);
                assert(wr->num_sge == 1);
                assert(elts_head < rxq->elts_n);
@@ -1698,9 +1647,8 @@ mlx4_rx_burst(void *dpdk_rxq, struct rte_mbuf **pkts, uint16_t pkts_n)
                wr_next = &wr->next;
                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, wr_id, wc->status,
+                       DEBUG("rxq=%p: bad work completion status (%d): %s",
+                             (void *)rxq, wc->status,
                              ibv_wc_status_str(wc->status));
                        /* Increment dropped packets counter. */
                        ++rxq->stats.idropped;
@@ -1712,9 +1660,8 @@ mlx4_rx_burst(void *dpdk_rxq, struct rte_mbuf **pkts, uint16_t pkts_n)
                         * Unable to allocate a replacement mbuf,
                         * repost WR.
                         */
-                       DEBUG("rxq=%p, wr_id=%" PRIu32 ":"
-                             " can't allocate a new mbuf",
-                             (void *)rxq, WR_ID(wr_id).id);
+                       DEBUG("rxq=%p: can't allocate a new mbuf",
+                             (void *)rxq);
                        /* Increase out of memory counters. */
                        ++rxq->stats.rx_nombuf;
                        ++rxq->priv->dev->data->rx_mbuf_alloc_failed;
@@ -1724,10 +1671,7 @@ mlx4_rx_burst(void *dpdk_rxq, struct rte_mbuf **pkts, uint16_t pkts_n)
                /* Reconfigure sge to use rep instead of seg. */
                elt->sge.addr = (uintptr_t)rep->buf_addr + RTE_PKTMBUF_HEADROOM;
                assert(elt->sge.lkey == rxq->mr->lkey);
-               WR_ID(wr->wr_id).offset =
-                       (((uintptr_t)rep->buf_addr + RTE_PKTMBUF_HEADROOM) -
-                        (uintptr_t)rep);
-               assert(WR_ID(wr->wr_id).id == WR_ID(wr_id).id);
+               elt->buf = rep;
 
                /* Update seg information. */
                SET_DATA_OFF(seg, RTE_PKTMBUF_HEADROOM);
@@ -3659,7 +3603,6 @@ RTE_INIT(rte_mlx4_pmd_init);
 static void
 rte_mlx4_pmd_init(void)
 {
-       RTE_BUILD_BUG_ON(sizeof(wr_id_t) != sizeof(uint64_t));
        /*
         * RDMAV_HUGEPAGES_SAFE tells ibv_fork_init() we intend to use
         * huge pages. Calling ibv_fork_init() during init allows

diff --git a/drivers/net/mlx4/mlx4.h b/drivers/net/mlx4/mlx4.h
index 772784f..c619c87 100644 (file)
--- a/drivers/net/mlx4/mlx4.h
+++ b/drivers/net/mlx4/mlx4.h
@@ -148,7 +148,7 @@ struct mlx4_rxq_stats {
 struct rxq_elt {
        struct ibv_recv_wr wr; /* Work Request. */
        struct ibv_sge sge; /* Scatter/Gather Element. */
-       /* mbuf pointer is derived from WR_ID(wr.wr_id).offset. */
+       struct rte_mbuf *buf; /**< Buffer. */
 };
 
 /* RX queue descriptor. */