netdev - Re: [PATCH net-next 4/6] net: hip04: Don't free the tx skb when the buffer is not ready for xmit

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Message-ID: <552F560D.4070309@huawei.com>
Date:	Thu, 16 Apr 2015 14:26:21 +0800
From:	Ding Tianhong <dingtianhong@...wei.com>
To:	Arnd Bergmann <arnd@...db.de>
CC:	<davem@...emloft.net>, <grant.likely@...aro.org>,
	<sergei.shtylyov@...entembedded.com>,
	<linux-arm-kernel@...ts.infradead.org>, <eric.dumazet@...il.com>,
	<zhangfei.gao@...aro.org>, <joe@...ches.com>,
	<netdev@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux@....linux.org.uk>
Subject: Re: [PATCH net-next 4/6] net: hip04: Don't free the tx skb when the
 buffer is not ready for xmit

On 2015/4/15 22:19, Arnd Bergmann wrote:
> On Wednesday 15 April 2015 20:30:06 Ding Tianhong wrote:
>> @@ -489,6 +487,8 @@ static int hip04_mac_start_xmit(struct sk_buff *skb, struct net_device *ndev)
>>  
>>         /* Ensure tx_head update visible to tx reclaim */
>>         smp_wmb();
>> +       count++;
>> +       priv->tx_head = TX_NEXT(tx_head);
>>  
>>
> 
> Something is wrong here, the comment does not match the code any more, because
> the smp_wmb() won't actually make the tx_head update visible.
> 
> 	Arnd
> 
Yes, the smp_wmb() could only make sure the tx buffer was ready to xmit.

> .
> 


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