On Fri, 28 Jun 2019 14:39:29 -0700, Shannon Nelson wrote:
> +static int ionic_tx(struct queue *q, struct sk_buff *skb)
> +{
> + struct tx_stats *stats = q_to_tx_stats(q);
> + int err;
> +
> + if (skb->ip_summed == CHECKSUM_PARTIAL)
> + err = ionic_tx_calc_csum(q, skb);
> + else
> + err = ionic_tx_calc_no_csum(q, skb);
> + if (err)
> + return err;
> +
> + err = ionic_tx_skb_frags(q, skb);
> + if (err)
> + return err;
> +
> + skb_tx_timestamp(skb);
> + stats->pkts++;
> + stats->bytes += skb->len;
Presumably this is 64bit so you should use
u64_stats_update_begin()
u64_stats_update_end()
around it (and all other stats).
> +
> + ionic_txq_post(q, !netdev_xmit_more(), ionic_tx_clean, skb);
> +
> + return 0;
> +}
> +
> +static int ionic_tx_descs_needed(struct queue *q, struct sk_buff *skb)
> +{
> + struct tx_stats *stats = q_to_tx_stats(q);
> + int err;
> +
> + /* If TSO, need roundup(skb->len/mss) descs */
> + if (skb_is_gso(skb))
> + return (skb->len / skb_shinfo(skb)->gso_size) + 1;
> +
> + /* If non-TSO, just need 1 desc and nr_frags sg elems */
> + if (skb_shinfo(skb)->nr_frags <= IONIC_TX_MAX_SG_ELEMS)
> + return 1;
> +
> + /* Too many frags, so linearize */
> + err = skb_linearize(skb);
> + if (err)
> + return err;
> +
> + stats->linearize++;
> +
> + /* Need 1 desc and zero sg elems */
> + return 1;
> +}
> +
> +netdev_tx_t ionic_start_xmit(struct sk_buff *skb, struct net_device *netdev)
> +{
> + u16 queue_index = skb_get_queue_mapping(skb);
> + struct lif *lif = netdev_priv(netdev);
> + struct queue *q;
> + int ndescs;
> + int err;
> +
> + if (unlikely(!test_bit(LIF_UP, lif->state))) {
> + dev_kfree_skb(skb);
> + return NETDEV_TX_OK;
> + }
> +
> + if (likely(lif_to_txqcq(lif, queue_index)))
> + q = lif_to_txq(lif, queue_index);
> + else
> + q = lif_to_txq(lif, 0);
> +
> + ndescs = ionic_tx_descs_needed(q, skb);
> + if (ndescs < 0)
> + goto err_out_drop;
> +
> + if (!ionic_q_has_space(q, ndescs)) {
> + netif_stop_subqueue(netdev, queue_index);
> + q->stop++;
> +
> + /* Might race with ionic_tx_clean, check again */
> + smp_rmb();
> + if (ionic_q_has_space(q, ndescs)) {
> + netif_wake_subqueue(netdev, queue_index);
> + q->wake++;
> + } else {
> + return NETDEV_TX_BUSY;
This should never really happen..
> + }
> + }
> +
> + if (skb_is_gso(skb))
> + err = ionic_tx_tso(q, skb);
> + else
> + err = ionic_tx(q, skb);
> +
> + if (err)
> + goto err_out_drop;
.. at this point if you can't guarantee fitting biggest possible frame
in, you have to stop the ring.
> + return NETDEV_TX_OK;
> +
> +err_out_drop:
> + q->drop++;
> + dev_kfree_skb(skb);
> + return NETDEV_TX_OK;
> +}
