netdev - Re: [PATCH net-next v3] Add support of Cavium Liquidio ethernet adapters

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Date:	Thu, 18 Dec 2014 23:14:01 -0800
From:	Stephen Hemminger <stephen@...workplumber.org>
To:	Raghu Vatsavayi <rvatsavayi@...iumnetworks.com>
Cc:	<davem@...emloft.net>, <netdev@...r.kernel.org>,
	Derek Chickles <derek.chickles@...iumnetworks.com>,
	Satanand Burla <satananda.burla@...iumnetworks.com>,
	Felix Manlunas <felix.manlunas@...iumnetworks.com>,
	Raghu Vatsavayi <raghu.vatsavayi@...iumnetworks.com>
Subject: Re: [PATCH net-next v3] Add support of Cavium Liquidio ethernet
 adapters

On Thu, 18 Dec 2014 19:25:19 -0800
Raghu Vatsavayi <rvatsavayi@...iumnetworks.com> wrote:

> +static int liquidio_xmit(struct sk_buff *skb, struct net_device *netdev)
> +{
> +	struct lio *lio;
> +	struct octnet_buf_free_info *finfo;
> +	union octnic_cmd_setup cmdsetup;
> +	struct octnic_data_pkt ndata;
> +	struct octeon_device *oct;
> +	int cpu = 0, status = 0;
> +	int q_idx = 0;
> +	int xmit_more;
> +
> +	lio = GET_LIO(netdev);
> +	oct = lio->oct_dev;
> +	atomic64_inc((atomic64_t *)&lio->stats.tx_packets);
> +	lio->stats.tx_bytes += skb->len;
> +
> +	if (!ifstate_check(lio, LIO_IFSTATE_TXENABLED)) {
> +		lio_info(lio, tx_err, "Transmit Busy, not enabled\n");
> +		return NETDEV_TX_BUSY;
> +	}

This kind of busy handling in transmit, will cause the send in higher
level to retry and spin the CPU. Better to do proper flow control
like other drivers.
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