netdev - Re: [PATCH net-next 2/2] net: bcmgenet: add support for xmit

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Date:	Mon, 09 Mar 2015 15:36:14 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Florian Fainelli <f.fainelli@...il.com>
Cc:	netdev <netdev@...r.kernel.org>,
	David Miller <davem@...emloft.net>,
	Petri Gynther <pgynther@...gle.com>,
	Jaedon Shin <jaedon.shin@...il.com>
Subject: Re: [PATCH net-next 2/2] net: bcmgenet: add support for xmit_more

On Mon, 2015-03-09 at 15:13 -0700, Florian Fainelli wrote:

> bcmgenet_xmit() and bcmgenet_tx_reclaim() are the only two functions
> that can stop a queue, and they are using a spinlock to avoid that.

It does not matter.

If you hit the condition :

if (ring->free_bds <= (MAX_SKB_FRAGS + 1))
     netif_tx_stop_queue(txq);

Then maybe you filled the ring buffer with skb having xmit_more set, and
you never did a bcmgenet_tdma_ring_writel()

Look at other drivers using xmit_more, because you have to reverse
things.

The skeleton is :

maybe_stop_tx();

if (netif_xmit_stopped(txring_txq(tx_ring)) || !skb->xmit_more) {
    mmiiowb();
    ...
}



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