netdev - Re: [git patches] net driver updates

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Message-ID: <47BCD0DF.1050205@chelsio.com>
Date:	Wed, 20 Feb 2008 17:16:15 -0800
From:	Divy Le Ray <divy@...lsio.com>
To:	Jeff Garzik <jeff@...zik.org>
CC:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [git patches] net driver updates

Jeff Garzik wrote:
> Divy Le Ray wrote:
>> Jeff Garzik wrote:
>>> Mostly fixes, a few cleanups (generally assisting fixes), and an
>>> exception for PS3 wireless because it had been posted, reviewed and
>>> acked for a while, just not committed.
>>>
>>> Please pull from 'upstream-davem' branch of
>>> master.kernel.org:/pub/scm/linux/kernel/git/jgarzik/netdev-2.6.git 
>>> upstream-davem
>>>
>>> to receive the following updates:
>>>
>>>  
>>>  drivers/net/cxgb3/sge.c          |   35 +-
>>>    diff --git a/drivers/net/cxgb3/sge.c b/drivers/net/cxgb3/sge.c
>>> index 9ca8c66..979f3fc 100644
>>> --- a/drivers/net/cxgb3/sge.c
>>> +++ b/drivers/net/cxgb3/sge.c
>>> @@ -1059,6 +1059,14 @@ static void write_tx_pkt_wr(struct adapter 
>>> *adap, struct sk_buff *skb,
>>>               htonl(V_WR_TID(q->token)));
>>>  }
>>>  
>>> +static inline void t3_stop_queue(struct net_device *dev, struct 
>>> sge_qset *qs,
>>> +                 struct sge_txq *q)
>>> +{
>>> +    netif_stop_queue(dev);
>>> +    set_bit(TXQ_ETH, &qs->txq_stopped);
>>> +    q->stops++;
>>> +}
>>> +
>>>  /**
>>>   *    eth_xmit - add a packet to the Ethernet Tx queue
>>>   *    @skb: the packet
>>> @@ -1090,31 +1098,18 @@ int t3_eth_xmit(struct sk_buff *skb, struct 
>>> net_device *dev)
>>>      ndesc = calc_tx_descs(skb);
>>>  
>>>      if (unlikely(credits < ndesc)) {
>>> -        if (!netif_queue_stopped(dev)) {
>>> -            netif_stop_queue(dev);
>>> -            set_bit(TXQ_ETH, &qs->txq_stopped);
>>> -            q->stops++;
>>> -            dev_err(&adap->pdev->dev,
>>> -                "%s: Tx ring %u full while queue awake!\n",
>>> -                dev->name, q->cntxt_id & 7);
>>> -        }
>>> +        t3_stop_queue(dev, qs, q);
>>> +        dev_err(&adap->pdev->dev,
>>> +            "%s: Tx ring %u full while queue awake!\n",
>>> +            dev->name, q->cntxt_id & 7);
>>>          spin_unlock(&q->lock);
>>>          return NETDEV_TX_BUSY;
>>>      }
>>>  
>>>      q->in_use += ndesc;
>>> -    if (unlikely(credits - ndesc < q->stop_thres)) {
>>> -        q->stops++;
>>> -        netif_stop_queue(dev);
>>> -        set_bit(TXQ_ETH, &qs->txq_stopped);
>>> -#if !USE_GTS
>>> -        if (should_restart_tx(q) &&
>>> -            test_and_clear_bit(TXQ_ETH, &qs->txq_stopped)) {
>>> -            q->restarts++;
>>> -            netif_wake_queue(dev);
>>> -        }
>>> -#endif
>>> -    }
>>> +    if (unlikely(credits - ndesc < q->stop_thres))
>>> +        if (USE_GTS || !should_restart_tx(q))
>>> +            t3_stop_queue(dev, qs, q);
>>>  
>>>      gen = q->gen;
>>>      q->unacked += ndesc;
>>>   
>> Hi Jeff,
>>
>> I thought I had NAK'ed the patch modifying sge.c from Krishna Kumar.
>> Looking back at my answer at the time, I was obviously unclear.
>> Can you please revert the drivers/net/cxgb3sge.c change ?
>
> Explain why, so I can include it in the changelog please...

Hi Jeff,

The first part of the patch removes the !netif_queue_stopped(dev).
It opens the race discussed a while ago between Stephen hemminger and 
David Miller:
http://marc.info/?l=linux-netdev&m=113383224512427&w=2

The second part of the patch breaks the current usage of txq_stopped and 
the logic that stops and restarts the Tx queue.

Cheers,
Divy

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