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MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, 29 Aug 2019 11:27:16 -0700, Shannon Nelson wrote: > +netdev_tx_t ionic_start_xmit(struct sk_buff *skb, struct net_device *netdev) > +{ > + u16 queue_index = skb_get_queue_mapping(skb); > + struct ionic_lif *lif = netdev_priv(netdev); > + struct ionic_queue *q; > + int ndescs; > + int err; > + > + if (unlikely(!test_bit(IONIC_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)) { You should stop the queue in advance, whenever you can't ensure that a max size frame can be placed on the ring. Requeuing is very expensive so modern drivers should try to never return NETDEV_TX_BUSY > + 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; > + } > + } > + > + if (skb_is_gso(skb)) > + err = ionic_tx_tso(q, skb); > + else > + err = ionic_tx(q, skb); > + > + if (err) > + goto err_out_drop; > + > + return NETDEV_TX_OK; > + > +err_out_drop: > + netif_stop_subqueue(netdev, queue_index); This stopping of the queue is suspicious, if ionic_tx() fails there's no guarantee the queue will ever be woken up, no? > + q->stop++; > + q->drop++; > + dev_kfree_skb(skb); > + return NETDEV_TX_OK; > +}