net/ena: remove Tx mbuf linearization

The linearization of the mbuf isn't common practice for the PMD, as it
can expose it's capabilities to the upper layer using
rte_eth_dev_info_get().

Moreover, the rte_eth_tx_prepare() function should also verify if the
number of segments inside the mbuf isn't too high.

Because of those 2 circumstances, it may be safer to avoid modifying
mbuf on PMD's Tx side and remove linearization at all. Instead, add
verification of the number of segments to the eth_ena_prep_pkts().

Signed-off-by: Michal Krawczyk <mk@semihalf.com>
Reviewed-by: Artur Rojek <ar@semihalf.com>
Reviewed-by: Dawid Gorecki <dgr@semihalf.com>
Reviewed-by: Igor Chauskin <igorch@amazon.com>
Reviewed-by: Shai Brandes <shaibran@amazon.com>

diff --git a/drivers/net/ena/ena_ethdev.c b/drivers/net/ena/ena_ethdev.c
index db2b5ec8e77b741e87eeaa00f827b99d0bcd3598..deaee30664227fea6ea583656909ed36abfb1373 100644 (file)
--- a/drivers/net/ena/ena_ethdev.c
+++ b/drivers/net/ena/ena_ethdev.c
@@ -93,8 +93,6 @@ static const struct ena_stats ena_stats_tx_strings[] = {
        ENA_STAT_TX_ENTRY(cnt),
        ENA_STAT_TX_ENTRY(bytes),
        ENA_STAT_TX_ENTRY(prepare_ctx_err),
-       ENA_STAT_TX_ENTRY(linearize),
-       ENA_STAT_TX_ENTRY(linearize_failed),
        ENA_STAT_TX_ENTRY(tx_poll),
        ENA_STAT_TX_ENTRY(doorbells),
        ENA_STAT_TX_ENTRY(bad_req_id),
@@ -2408,6 +2406,17 @@ eth_ena_prep_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
                        return i;
                }
 
+               if (unlikely(m->nb_segs >= tx_ring->sgl_size &&
+                   !(tx_ring->tx_mem_queue_type == ENA_ADMIN_PLACEMENT_POLICY_DEV &&
+                     m->nb_segs == tx_ring->sgl_size &&
+                     m->data_len < tx_ring->tx_max_header_size))) {
+                       PMD_TX_LOG(DEBUG,
+                               "mbuf[%" PRIu32 "] has too many segments: %" PRIu16 "\n",
+                               i, m->nb_segs);
+                       rte_errno = EINVAL;
+                       return i;
+               }
+
 #ifdef RTE_LIBRTE_ETHDEV_DEBUG
                /* Check if requested offload is also enabled for the queue */
                if ((ol_flags & RTE_MBUF_F_TX_IP_CKSUM &&
@@ -2554,56 +2563,6 @@ static void ena_update_hints(struct ena_adapter *adapter,
        }
 }
 
-static int ena_check_space_and_linearize_mbuf(struct ena_ring *tx_ring,
-                                             struct rte_mbuf *mbuf)
-{
-       struct ena_com_dev *ena_dev;
-       int num_segments, header_len, rc;
-
-       ena_dev = &tx_ring->adapter->ena_dev;
-       num_segments = mbuf->nb_segs;
-       header_len = mbuf->data_len;
-
-       if (likely(num_segments < tx_ring->sgl_size))
-               goto checkspace;
-
-       if (ena_dev->tx_mem_queue_type == ENA_ADMIN_PLACEMENT_POLICY_DEV &&
-           (num_segments == tx_ring->sgl_size) &&
-           (header_len < tx_ring->tx_max_header_size))
-               goto checkspace;
-
-       /* Checking for space for 2 additional metadata descriptors due to
-        * possible header split and metadata descriptor. Linearization will
-        * be needed so we reduce the segments number from num_segments to 1
-        */
-       if (!ena_com_sq_have_enough_space(tx_ring->ena_com_io_sq, 3)) {
-               PMD_TX_LOG(DEBUG, "Not enough space in the Tx queue\n");
-               return ENA_COM_NO_MEM;
-       }
-       ++tx_ring->tx_stats.linearize;
-       rc = rte_pktmbuf_linearize(mbuf);
-       if (unlikely(rc)) {
-               PMD_TX_LOG(WARNING, "Mbuf linearize failed\n");
-               rte_atomic64_inc(&tx_ring->adapter->drv_stats->ierrors);
-               ++tx_ring->tx_stats.linearize_failed;
-               return rc;
-       }
-
-       return 0;
-
-checkspace:
-       /* Checking for space for 2 additional metadata descriptors due to
-        * possible header split and metadata descriptor
-        */
-       if (!ena_com_sq_have_enough_space(tx_ring->ena_com_io_sq,
-                                         num_segments + 2)) {
-               PMD_TX_LOG(DEBUG, "Not enough space in the Tx queue\n");
-               return ENA_COM_NO_MEM;
-       }
-
-       return 0;
-}
-
 static void ena_tx_map_mbuf(struct ena_ring *tx_ring,
        struct ena_tx_buffer *tx_info,
        struct rte_mbuf *mbuf,
@@ -2688,9 +2647,14 @@ static int ena_xmit_mbuf(struct ena_ring *tx_ring, struct rte_mbuf *mbuf)
        int nb_hw_desc;
        int rc;
 
-       rc = ena_check_space_and_linearize_mbuf(tx_ring, mbuf);
-       if (unlikely(rc))
-               return rc;
+       /* Checking for space for 2 additional metadata descriptors due to
+        * possible header split and metadata descriptor
+        */
+       if (!ena_com_sq_have_enough_space(tx_ring->ena_com_io_sq,
+                                         mbuf->nb_segs + 2)) {
+               PMD_DRV_LOG(DEBUG, "Not enough space in the tx queue\n");
+               return ENA_COM_NO_MEM;
+       }
 
        next_to_use = tx_ring->next_to_use;
 

diff --git a/drivers/net/ena/ena_ethdev.h b/drivers/net/ena/ena_ethdev.h
index f99e4f3984a058bce62ce565efc9e778d261f21b..f47ba3fb02485f885976fa4b121ddc5c57254b7e 100644 (file)
--- a/drivers/net/ena/ena_ethdev.h
+++ b/drivers/net/ena/ena_ethdev.h
@@ -103,8 +103,6 @@ struct ena_stats_tx {
        u64 cnt;
        u64 bytes;
        u64 prepare_ctx_err;
-       u64 linearize;
-       u64 linearize_failed;
        u64 tx_poll;
        u64 doorbells;
        u64 bad_req_id;