net/sfc: remove Tx DMA descriptor boundary crossing limit
[dpdk.git] / drivers / net / sfc / sfc_tx.c
index ef4be45..5bb31ad 100644 (file)
  */
 
 #include "sfc.h"
+#include "sfc_debug.h"
 #include "sfc_log.h"
 #include "sfc_ev.h"
 #include "sfc_tx.h"
+#include "sfc_tweak.h"
+
+/*
+ * Maximum number of TX queue flush attempts in case of
+ * failure or flush timeout
+ */
+#define SFC_TX_QFLUSH_ATTEMPTS         (3)
+
+/*
+ * Time to wait between event queue polling attempts when waiting for TX
+ * queue flush done or flush failed events
+ */
+#define SFC_TX_QFLUSH_POLL_WAIT_MS     (1)
+
+/*
+ * Maximum number of event queue polling attempts when waiting for TX queue
+ * flush done or flush failed events; it defines TX queue flush attempt timeout
+ * together with SFC_TX_QFLUSH_POLL_WAIT_MS
+ */
+#define SFC_TX_QFLUSH_POLL_ATTEMPTS    (2000)
+
+static int
+sfc_tx_qcheck_conf(struct sfc_adapter *sa, uint16_t nb_tx_desc,
+                  const struct rte_eth_txconf *tx_conf)
+{
+       unsigned int flags = tx_conf->txq_flags;
+       const efx_nic_cfg_t *encp = efx_nic_cfg_get(sa->nic);
+       int rc = 0;
+
+       if (tx_conf->tx_rs_thresh != 0) {
+               sfc_err(sa, "RS bit in transmit descriptor is not supported");
+               rc = EINVAL;
+       }
+
+       if (tx_conf->tx_free_thresh > EFX_TXQ_LIMIT(nb_tx_desc)) {
+               sfc_err(sa,
+                       "TxQ free threshold too large: %u vs maximum %u",
+                       tx_conf->tx_free_thresh, EFX_TXQ_LIMIT(nb_tx_desc));
+               rc = EINVAL;
+       }
+
+       if (tx_conf->tx_thresh.pthresh != 0 ||
+           tx_conf->tx_thresh.hthresh != 0 ||
+           tx_conf->tx_thresh.wthresh != 0) {
+               sfc_err(sa,
+                       "prefetch/host/writeback thresholds are not supported");
+               rc = EINVAL;
+       }
+
+       if (!encp->enc_hw_tx_insert_vlan_enabled &&
+           (flags & ETH_TXQ_FLAGS_NOVLANOFFL) == 0) {
+               sfc_err(sa, "VLAN offload is not supported");
+               rc = EINVAL;
+       }
+
+       if ((flags & ETH_TXQ_FLAGS_NOXSUMSCTP) == 0) {
+               sfc_err(sa, "SCTP offload is not supported");
+               rc = EINVAL;
+       }
+
+       /* We either perform both TCP and UDP offload, or no offload at all */
+       if (((flags & ETH_TXQ_FLAGS_NOXSUMTCP) == 0) !=
+           ((flags & ETH_TXQ_FLAGS_NOXSUMUDP) == 0)) {
+               sfc_err(sa, "TCP and UDP offloads can't be set independently");
+               rc = EINVAL;
+       }
+
+       return rc;
+}
+
+void
+sfc_tx_qflush_done(struct sfc_txq *txq)
+{
+       txq->state |= SFC_TXQ_FLUSHED;
+       txq->state &= ~SFC_TXQ_FLUSHING;
+}
+
+static void
+sfc_tx_reap(struct sfc_txq *txq)
+{
+       unsigned int    completed;
+
+
+       sfc_ev_qpoll(txq->evq);
+
+       for (completed = txq->completed;
+            completed != txq->pending; completed++) {
+               struct sfc_tx_sw_desc *txd;
+
+               txd = &txq->sw_ring[completed & txq->ptr_mask];
+
+               if (txd->mbuf != NULL) {
+                       rte_pktmbuf_free(txd->mbuf);
+                       txd->mbuf = NULL;
+               }
+       }
+
+       txq->completed = completed;
+}
+
+int
+sfc_tx_qinit(struct sfc_adapter *sa, unsigned int sw_index,
+            uint16_t nb_tx_desc, unsigned int socket_id,
+            const struct rte_eth_txconf *tx_conf)
+{
+       const efx_nic_cfg_t *encp = efx_nic_cfg_get(sa->nic);
+       struct sfc_txq_info *txq_info;
+       struct sfc_evq *evq;
+       struct sfc_txq *txq;
+       unsigned int evq_index = sfc_evq_index_by_txq_sw_index(sa, sw_index);
+       int rc = 0;
+
+       sfc_log_init(sa, "TxQ = %u", sw_index);
+
+       rc = sfc_tx_qcheck_conf(sa, nb_tx_desc, tx_conf);
+       if (rc != 0)
+               goto fail_bad_conf;
+
+       SFC_ASSERT(sw_index < sa->txq_count);
+       txq_info = &sa->txq_info[sw_index];
+
+       SFC_ASSERT(nb_tx_desc <= sa->txq_max_entries);
+       txq_info->entries = nb_tx_desc;
+
+       rc = sfc_ev_qinit(sa, evq_index, txq_info->entries, socket_id);
+       if (rc != 0)
+               goto fail_ev_qinit;
+
+       evq = sa->evq_info[evq_index].evq;
+
+       rc = ENOMEM;
+       txq = rte_zmalloc_socket("sfc-txq", sizeof(*txq), 0, socket_id);
+       if (txq == NULL)
+               goto fail_txq_alloc;
+
+       rc = sfc_dma_alloc(sa, "txq", sw_index, EFX_TXQ_SIZE(txq_info->entries),
+                          socket_id, &txq->mem);
+       if (rc != 0)
+               goto fail_dma_alloc;
+
+       rc = ENOMEM;
+       txq->pend_desc = rte_calloc_socket("sfc-txq-pend-desc",
+                                          EFX_TXQ_LIMIT(txq_info->entries),
+                                          sizeof(efx_desc_t), 0, socket_id);
+       if (txq->pend_desc == NULL)
+               goto fail_pend_desc_alloc;
+
+       rc = ENOMEM;
+       txq->sw_ring = rte_calloc_socket("sfc-txq-desc", txq_info->entries,
+                                        sizeof(*txq->sw_ring), 0, socket_id);
+       if (txq->sw_ring == NULL)
+               goto fail_desc_alloc;
+
+       if (sa->tso) {
+               rc = sfc_tso_alloc_tsoh_objs(txq->sw_ring, txq_info->entries,
+                                            socket_id);
+               if (rc != 0)
+                       goto fail_alloc_tsoh_objs;
+       }
+
+       txq->state = SFC_TXQ_INITIALIZED;
+       txq->ptr_mask = txq_info->entries - 1;
+       txq->free_thresh = (tx_conf->tx_free_thresh) ? tx_conf->tx_free_thresh :
+                                                    SFC_TX_DEFAULT_FREE_THRESH;
+       txq->dma_desc_size_max = encp->enc_tx_dma_desc_size_max;
+       txq->hw_index = sw_index;
+       txq->flags = tx_conf->txq_flags;
+       txq->evq = evq;
+
+       evq->txq = txq;
+
+       txq_info->txq = txq;
+       txq_info->deferred_start = (tx_conf->tx_deferred_start != 0);
+
+       return 0;
+
+fail_alloc_tsoh_objs:
+       rte_free(txq->sw_ring);
+
+fail_desc_alloc:
+       rte_free(txq->pend_desc);
+
+fail_pend_desc_alloc:
+       sfc_dma_free(sa, &txq->mem);
+
+fail_dma_alloc:
+       rte_free(txq);
+
+fail_txq_alloc:
+       sfc_ev_qfini(sa, evq_index);
+
+fail_ev_qinit:
+       txq_info->entries = 0;
+
+fail_bad_conf:
+       sfc_log_init(sa, "failed (TxQ = %u, rc = %d)", sw_index, rc);
+       return rc;
+}
+
+void
+sfc_tx_qfini(struct sfc_adapter *sa, unsigned int sw_index)
+{
+       struct sfc_txq_info *txq_info;
+       struct sfc_txq *txq;
+
+       sfc_log_init(sa, "TxQ = %u", sw_index);
+
+       SFC_ASSERT(sw_index < sa->txq_count);
+       txq_info = &sa->txq_info[sw_index];
+
+       txq = txq_info->txq;
+       SFC_ASSERT(txq != NULL);
+       SFC_ASSERT(txq->state == SFC_TXQ_INITIALIZED);
+
+       sfc_tso_free_tsoh_objs(txq->sw_ring, txq_info->entries);
+
+       txq_info->txq = NULL;
+       txq_info->entries = 0;
+
+       rte_free(txq->sw_ring);
+       rte_free(txq->pend_desc);
+       sfc_dma_free(sa, &txq->mem);
+       rte_free(txq);
+}
 
 static int
 sfc_tx_qinit_info(struct sfc_adapter *sa, unsigned int sw_index)
@@ -40,12 +265,64 @@ sfc_tx_qinit_info(struct sfc_adapter *sa, unsigned int sw_index)
        return 0;
 }
 
+static int
+sfc_tx_check_mode(struct sfc_adapter *sa, const struct rte_eth_txmode *txmode)
+{
+       int rc = 0;
+
+       switch (txmode->mq_mode) {
+       case ETH_MQ_TX_NONE:
+               break;
+       default:
+               sfc_err(sa, "Tx multi-queue mode %u not supported",
+                       txmode->mq_mode);
+               rc = EINVAL;
+       }
+
+       /*
+        * These features are claimed to be i40e-specific,
+        * but it does make sense to double-check their absence
+        */
+       if (txmode->hw_vlan_reject_tagged) {
+               sfc_err(sa, "Rejecting tagged packets not supported");
+               rc = EINVAL;
+       }
+
+       if (txmode->hw_vlan_reject_untagged) {
+               sfc_err(sa, "Rejecting untagged packets not supported");
+               rc = EINVAL;
+       }
+
+       if (txmode->hw_vlan_insert_pvid) {
+               sfc_err(sa, "Port-based VLAN insertion not supported");
+               rc = EINVAL;
+       }
+
+       return rc;
+}
+
 int
 sfc_tx_init(struct sfc_adapter *sa)
 {
+       const efx_nic_cfg_t *encp = efx_nic_cfg_get(sa->nic);
+       const struct rte_eth_conf *dev_conf = &sa->eth_dev->data->dev_conf;
        unsigned int sw_index;
        int rc = 0;
 
+       /*
+        * The datapath implementation assumes absence of boundary
+        * limits on Tx DMA descriptors. Addition of these checks on
+        * datapath would simply make the datapath slower.
+        */
+       if (encp->enc_tx_dma_desc_boundary != 0) {
+               rc = ENOTSUP;
+               goto fail_tx_dma_desc_boundary;
+       }
+
+       rc = sfc_tx_check_mode(sa, &dev_conf->txmode);
+       if (rc != 0)
+               goto fail_check_mode;
+
        sa->txq_count = sa->eth_dev->data->nb_tx_queues;
 
        sa->txq_info = rte_calloc_socket("sfc-txqs", sa->txq_count,
@@ -69,6 +346,8 @@ fail_tx_qinit_info:
 fail_txqs_alloc:
        sa->txq_count = 0;
 
+fail_check_mode:
+fail_tx_dma_desc_boundary:
        sfc_log_init(sa, "failed (rc = %d)", rc);
        return rc;
 }
@@ -76,7 +355,430 @@ fail_txqs_alloc:
 void
 sfc_tx_fini(struct sfc_adapter *sa)
 {
+       int sw_index;
+
+       sw_index = sa->txq_count;
+       while (--sw_index >= 0) {
+               if (sa->txq_info[sw_index].txq != NULL)
+                       sfc_tx_qfini(sa, sw_index);
+       }
+
        rte_free(sa->txq_info);
        sa->txq_info = NULL;
        sa->txq_count = 0;
 }
+
+int
+sfc_tx_qstart(struct sfc_adapter *sa, unsigned int sw_index)
+{
+       struct rte_eth_dev_data *dev_data;
+       struct sfc_txq_info *txq_info;
+       struct sfc_txq *txq;
+       struct sfc_evq *evq;
+       uint16_t flags;
+       unsigned int desc_index;
+       int rc = 0;
+
+       sfc_log_init(sa, "TxQ = %u", sw_index);
+
+       SFC_ASSERT(sw_index < sa->txq_count);
+       txq_info = &sa->txq_info[sw_index];
+
+       txq = txq_info->txq;
+
+       SFC_ASSERT(txq->state == SFC_TXQ_INITIALIZED);
+
+       evq = txq->evq;
+
+       rc = sfc_ev_qstart(sa, evq->evq_index);
+       if (rc != 0)
+               goto fail_ev_qstart;
+
+       /*
+        * It seems that DPDK has no controls regarding IPv4 offloads,
+        * hence, we always enable it here
+        */
+       if ((txq->flags & ETH_TXQ_FLAGS_NOXSUMTCP) ||
+           (txq->flags & ETH_TXQ_FLAGS_NOXSUMUDP)) {
+               flags = EFX_TXQ_CKSUM_IPV4;
+       } else {
+               flags = EFX_TXQ_CKSUM_IPV4 | EFX_TXQ_CKSUM_TCPUDP;
+
+               if (sa->tso)
+                       flags |= EFX_TXQ_FATSOV2;
+       }
+
+       rc = efx_tx_qcreate(sa->nic, sw_index, 0, &txq->mem,
+                           txq_info->entries, 0 /* not used on EF10 */,
+                           flags, evq->common,
+                           &txq->common, &desc_index);
+       if (rc != 0) {
+               if (sa->tso && (rc == ENOSPC))
+                       sfc_err(sa, "ran out of TSO contexts");
+
+               goto fail_tx_qcreate;
+       }
+
+       txq->added = txq->pending = txq->completed = desc_index;
+       txq->hw_vlan_tci = 0;
+
+       efx_tx_qenable(txq->common);
+
+       txq->state |= (SFC_TXQ_STARTED | SFC_TXQ_RUNNING);
+
+       /*
+        * It seems to be used by DPDK for debug purposes only ('rte_ether')
+        */
+       dev_data = sa->eth_dev->data;
+       dev_data->tx_queue_state[sw_index] = RTE_ETH_QUEUE_STATE_STARTED;
+
+       return 0;
+
+fail_tx_qcreate:
+       sfc_ev_qstop(sa, evq->evq_index);
+
+fail_ev_qstart:
+       return rc;
+}
+
+void
+sfc_tx_qstop(struct sfc_adapter *sa, unsigned int sw_index)
+{
+       struct rte_eth_dev_data *dev_data;
+       struct sfc_txq_info *txq_info;
+       struct sfc_txq *txq;
+       unsigned int retry_count;
+       unsigned int wait_count;
+       unsigned int txds;
+
+       sfc_log_init(sa, "TxQ = %u", sw_index);
+
+       SFC_ASSERT(sw_index < sa->txq_count);
+       txq_info = &sa->txq_info[sw_index];
+
+       txq = txq_info->txq;
+
+       if (txq->state == SFC_TXQ_INITIALIZED)
+               return;
+
+       SFC_ASSERT(txq->state & SFC_TXQ_STARTED);
+
+       txq->state &= ~SFC_TXQ_RUNNING;
+
+       /*
+        * Retry TX queue flushing in case of flush failed or
+        * timeout; in the worst case it can delay for 6 seconds
+        */
+       for (retry_count = 0;
+            ((txq->state & SFC_TXQ_FLUSHED) == 0) &&
+            (retry_count < SFC_TX_QFLUSH_ATTEMPTS);
+            ++retry_count) {
+               if (efx_tx_qflush(txq->common) != 0) {
+                       txq->state |= SFC_TXQ_FLUSHING;
+                       break;
+               }
+
+               /*
+                * Wait for TX queue flush done or flush failed event at least
+                * SFC_TX_QFLUSH_POLL_WAIT_MS milliseconds and not more
+                * than 2 seconds (SFC_TX_QFLUSH_POLL_WAIT_MS multiplied
+                * by SFC_TX_QFLUSH_POLL_ATTEMPTS)
+                */
+               wait_count = 0;
+               do {
+                       rte_delay_ms(SFC_TX_QFLUSH_POLL_WAIT_MS);
+                       sfc_ev_qpoll(txq->evq);
+               } while ((txq->state & SFC_TXQ_FLUSHING) &&
+                        wait_count++ < SFC_TX_QFLUSH_POLL_ATTEMPTS);
+
+               if (txq->state & SFC_TXQ_FLUSHING)
+                       sfc_err(sa, "TxQ %u flush timed out", sw_index);
+
+               if (txq->state & SFC_TXQ_FLUSHED)
+                       sfc_info(sa, "TxQ %u flushed", sw_index);
+       }
+
+       sfc_tx_reap(txq);
+
+       for (txds = 0; txds < txq_info->entries; txds++) {
+               if (txq->sw_ring[txds].mbuf != NULL) {
+                       rte_pktmbuf_free(txq->sw_ring[txds].mbuf);
+                       txq->sw_ring[txds].mbuf = NULL;
+               }
+       }
+
+       txq->state = SFC_TXQ_INITIALIZED;
+
+       efx_tx_qdestroy(txq->common);
+
+       sfc_ev_qstop(sa, txq->evq->evq_index);
+
+       /*
+        * It seems to be used by DPDK for debug purposes only ('rte_ether')
+        */
+       dev_data = sa->eth_dev->data;
+       dev_data->tx_queue_state[sw_index] = RTE_ETH_QUEUE_STATE_STOPPED;
+}
+
+int
+sfc_tx_start(struct sfc_adapter *sa)
+{
+       unsigned int sw_index;
+       int rc = 0;
+
+       sfc_log_init(sa, "txq_count = %u", sa->txq_count);
+
+       if (sa->tso) {
+               if (!efx_nic_cfg_get(sa->nic)->enc_fw_assisted_tso_v2_enabled) {
+                       sfc_warn(sa, "TSO support was unable to be restored");
+                       sa->tso = B_FALSE;
+               }
+       }
+
+       rc = efx_tx_init(sa->nic);
+       if (rc != 0)
+               goto fail_efx_tx_init;
+
+       for (sw_index = 0; sw_index < sa->txq_count; ++sw_index) {
+               if (!(sa->txq_info[sw_index].deferred_start) ||
+                   sa->txq_info[sw_index].deferred_started) {
+                       rc = sfc_tx_qstart(sa, sw_index);
+                       if (rc != 0)
+                               goto fail_tx_qstart;
+               }
+       }
+
+       return 0;
+
+fail_tx_qstart:
+       while (sw_index-- > 0)
+               sfc_tx_qstop(sa, sw_index);
+
+       efx_tx_fini(sa->nic);
+
+fail_efx_tx_init:
+       sfc_log_init(sa, "failed (rc = %d)", rc);
+       return rc;
+}
+
+void
+sfc_tx_stop(struct sfc_adapter *sa)
+{
+       unsigned int sw_index;
+
+       sfc_log_init(sa, "txq_count = %u", sa->txq_count);
+
+       sw_index = sa->txq_count;
+       while (sw_index-- > 0) {
+               if (sa->txq_info[sw_index].txq != NULL)
+                       sfc_tx_qstop(sa, sw_index);
+       }
+
+       efx_tx_fini(sa->nic);
+}
+
+/*
+ * The function is used to insert or update VLAN tag;
+ * the firmware has state of the firmware tag to insert per TxQ
+ * (controlled by option descriptors), hence, if the tag of the
+ * packet to be sent is different from one remembered by the firmware,
+ * the function will update it
+ */
+static unsigned int
+sfc_tx_maybe_insert_tag(struct sfc_txq *txq, struct rte_mbuf *m,
+                       efx_desc_t **pend)
+{
+       uint16_t this_tag = ((m->ol_flags & PKT_TX_VLAN_PKT) ?
+                            m->vlan_tci : 0);
+
+       if (this_tag == txq->hw_vlan_tci)
+               return 0;
+
+       /*
+        * The expression inside SFC_ASSERT() is not desired to be checked in
+        * a non-debug build because it might be too expensive on the data path
+        */
+       SFC_ASSERT(efx_nic_cfg_get(txq->evq->sa->nic)->enc_hw_tx_insert_vlan_enabled);
+
+       efx_tx_qdesc_vlantci_create(txq->common, rte_cpu_to_be_16(this_tag),
+                                   *pend);
+       (*pend)++;
+       txq->hw_vlan_tci = this_tag;
+
+       return 1;
+}
+
+uint16_t
+sfc_xmit_pkts(void *tx_queue, struct rte_mbuf **tx_pkts, uint16_t nb_pkts)
+{
+       struct sfc_txq *txq = (struct sfc_txq *)tx_queue;
+       unsigned int added = txq->added;
+       unsigned int pushed = added;
+       unsigned int pkts_sent = 0;
+       efx_desc_t *pend = &txq->pend_desc[0];
+       const unsigned int hard_max_fill = EFX_TXQ_LIMIT(txq->ptr_mask + 1);
+       const unsigned int soft_max_fill = hard_max_fill - txq->free_thresh;
+       unsigned int fill_level = added - txq->completed;
+       boolean_t reap_done;
+       int rc __rte_unused;
+       struct rte_mbuf **pktp;
+
+       if (unlikely((txq->state & SFC_TXQ_RUNNING) == 0))
+               goto done;
+
+       /*
+        * If insufficient space for a single packet is present,
+        * we should reap; otherwise, we shouldn't do that all the time
+        * to avoid latency increase
+        */
+       reap_done = (fill_level > soft_max_fill);
+
+       if (reap_done) {
+               sfc_tx_reap(txq);
+               /*
+                * Recalculate fill level since 'txq->completed'
+                * might have changed on reap
+                */
+               fill_level = added - txq->completed;
+       }
+
+       for (pkts_sent = 0, pktp = &tx_pkts[0];
+            (pkts_sent < nb_pkts) && (fill_level <= soft_max_fill);
+            pkts_sent++, pktp++) {
+               struct rte_mbuf         *m_seg = *pktp;
+               size_t                  pkt_len = m_seg->pkt_len;
+               unsigned int            pkt_descs = 0;
+               size_t                  in_off = 0;
+
+               /*
+                * Here VLAN TCI is expected to be zero in case if no
+                * DEV_TX_VLAN_OFFLOAD capability is advertised;
+                * if the calling app ignores the absence of
+                * DEV_TX_VLAN_OFFLOAD and pushes VLAN TCI, then
+                * TX_ERROR will occur
+                */
+               pkt_descs += sfc_tx_maybe_insert_tag(txq, m_seg, &pend);
+
+               if (m_seg->ol_flags & PKT_TX_TCP_SEG) {
+                       /*
+                        * We expect correct 'pkt->l[2, 3, 4]_len' values
+                        * to be set correctly by the caller
+                        */
+                       if (sfc_tso_do(txq, added, &m_seg, &in_off, &pend,
+                                      &pkt_descs, &pkt_len) != 0) {
+                               /* We may have reached this place for
+                                * one of the following reasons:
+                                *
+                                * 1) Packet header length is greater
+                                *    than SFC_TSOH_STD_LEN
+                                * 2) TCP header starts at more then
+                                *    208 bytes into the frame
+                                *
+                                * We will deceive RTE saying that we have sent
+                                * the packet, but we will actually drop it.
+                                * Hence, we should revert 'pend' to the
+                                * previous state (in case we have added
+                                * VLAN descriptor) and start processing
+                                * another one packet. But the original
+                                * mbuf shouldn't be orphaned
+                                */
+                               pend -= pkt_descs;
+
+                               rte_pktmbuf_free(*pktp);
+
+                               continue;
+                       }
+
+                       /*
+                        * We've only added 2 FATSOv2 option descriptors
+                        * and 1 descriptor for the linearized packet header.
+                        * The outstanding work will be done in the same manner
+                        * as for the usual non-TSO path
+                        */
+               }
+
+               for (; m_seg != NULL; m_seg = m_seg->next) {
+                       efsys_dma_addr_t        next_frag;
+                       size_t                  seg_len;
+
+                       seg_len = m_seg->data_len;
+                       next_frag = rte_mbuf_data_dma_addr(m_seg);
+
+                       /*
+                        * If we've started TSO transaction few steps earlier,
+                        * we'll skip packet header using an offset in the
+                        * current segment (which has been set to the
+                        * first one containing payload)
+                        */
+                       seg_len -= in_off;
+                       next_frag += in_off;
+                       in_off = 0;
+
+                       do {
+                               efsys_dma_addr_t        frag_addr = next_frag;
+                               size_t                  frag_len;
+
+                               /*
+                                * It is assumed here that there is no
+                                * limitation on address boundary
+                                * crossing by DMA descriptor.
+                                */
+                               frag_len = MIN(seg_len, txq->dma_desc_size_max);
+                               next_frag += frag_len;
+                               seg_len -= frag_len;
+                               pkt_len -= frag_len;
+
+                               efx_tx_qdesc_dma_create(txq->common,
+                                                       frag_addr, frag_len,
+                                                       (pkt_len == 0),
+                                                       pend++);
+
+                               pkt_descs++;
+                       } while (seg_len != 0);
+               }
+
+               added += pkt_descs;
+
+               fill_level += pkt_descs;
+               if (unlikely(fill_level > hard_max_fill)) {
+                       /*
+                        * Our estimation for maximum number of descriptors
+                        * required to send a packet seems to be wrong.
+                        * Try to reap (if we haven't yet).
+                        */
+                       if (!reap_done) {
+                               sfc_tx_reap(txq);
+                               reap_done = B_TRUE;
+                               fill_level = added - txq->completed;
+                               if (fill_level > hard_max_fill) {
+                                       pend -= pkt_descs;
+                                       break;
+                               }
+                       } else {
+                               pend -= pkt_descs;
+                               break;
+                       }
+               }
+
+               /* Assign mbuf to the last used desc */
+               txq->sw_ring[(added - 1) & txq->ptr_mask].mbuf = *pktp;
+       }
+
+       if (likely(pkts_sent > 0)) {
+               rc = efx_tx_qdesc_post(txq->common, txq->pend_desc,
+                                      pend - &txq->pend_desc[0],
+                                      txq->completed, &txq->added);
+               SFC_ASSERT(rc == 0);
+
+               if (likely(pushed != txq->added))
+                       efx_tx_qpush(txq->common, txq->added, pushed);
+       }
+
+#if SFC_TX_XMIT_PKTS_REAP_AT_LEAST_ONCE
+       if (!reap_done)
+               sfc_tx_reap(txq);
+#endif
+
+done:
+       return pkts_sent;
+}