enic: fix Tx hang when number of packets > queue size

If the nb_pkts parameter to rte_eth_tx_burst() was greater than
the TX descriptor count, a completion was not being requested
from the NIC, so descriptors would not be released back to the
host causing a lock-up.

Introduce a limit of how many TX descriptors can be used in a single
call to the enic PMD burst TX function before requesting a completion.

Fixes: d739ba4c6abf ("enic: improve Tx packet rate")

Signed-off-by: John Daley <johndale@cisco.com>

diff --git a/drivers/net/enic/enic_ethdev.c b/drivers/net/enic/enic_ethdev.c
index 4969476..6bea940 100644 (file)
--- a/drivers/net/enic/enic_ethdev.c
+++ b/drivers/net/enic/enic_ethdev.c
@@ -523,7 +523,7 @@ static void enicpmd_remove_mac_addr(struct rte_eth_dev *eth_dev, __rte_unused ui
 static uint16_t enicpmd_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
        uint16_t nb_pkts)
 {
-       unsigned int index;
+       uint16_t index;
        unsigned int frags;
        unsigned int pkt_len;
        unsigned int seg_len;
@@ -535,6 +535,7 @@ static uint16_t enicpmd_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
        unsigned short vlan_id;
        unsigned short ol_flags;
        uint8_t last_seg, eop;
+       unsigned int host_tx_descs = 0;
 
        for (index = 0; index < nb_pkts; index++) {
                tx_pkt = *tx_pkts++;
@@ -550,6 +551,7 @@ static uint16_t enicpmd_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
                                return index;
                        }
                }
+
                pkt_len = tx_pkt->pkt_len;
                vlan_id = tx_pkt->vlan_tci;
                ol_flags = tx_pkt->ol_flags;
@@ -559,9 +561,19 @@ static uint16_t enicpmd_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts,
                        next_tx_pkt = tx_pkt->next;
                        seg_len = tx_pkt->data_len;
                        inc_len += seg_len;
-                       eop = (pkt_len == inc_len) || (!next_tx_pkt);
-                       last_seg = eop &&
-                               (index == ((unsigned int)nb_pkts - 1));
+
+                       host_tx_descs++;
+                       last_seg = 0;
+                       eop = 0;
+                       if ((pkt_len == inc_len) || !next_tx_pkt) {
+                               eop = 1;
+                               /* post if last packet in batch or > thresh */
+                               if ((index == (nb_pkts - 1)) ||
+                                  (host_tx_descs > ENIC_TX_POST_THRESH)) {
+                                       last_seg = 1;
+                                       host_tx_descs = 0;
+                               }
+                       }
                        enic_send_pkt(enic, wq, tx_pkt, (unsigned short)seg_len,
                                      !frags, eop, last_seg, ol_flags, vlan_id);
                        tx_pkt = next_tx_pkt;

diff --git a/drivers/net/enic/enic_res.h b/drivers/net/enic/enic_res.h
index 33f2e84..00fa71d 100644 (file)
--- a/drivers/net/enic/enic_res.h
+++ b/drivers/net/enic/enic_res.h
@@ -53,6 +53,7 @@
 
 #define ENIC_NON_TSO_MAX_DESC          16
 #define ENIC_DEFAULT_RX_FREE_THRESH    32
+#define ENIC_TX_POST_THRESH            (ENIC_MIN_WQ_DESCS / 2)
 
 #define ENIC_SETTING(enic, f) ((enic->config.flags & VENETF_##f) ? 1 : 0)