Subject: Re: [PATCH v2] ethernet:arc: Fix racing of TX ring buffer

From: Lino Sanfilippo <[email-masked]>
Date: Sun, 22 May 2016 01:04:42 +0200

On 21.05.2016 21:47, Francois Romieu wrote:
> Shuyu Wei <[email-masked]> :
> [...]
>> diff --git a/drivers/net/ethernet/arc/emac_main.c b/drivers/net/ethernet/arc/emac_main.c
>> index a3a9392..c2447b0 100644
>> --- a/drivers/net/ethernet/arc/emac_main.c
>> +++ b/drivers/net/ethernet/arc/emac_main.c
>> @@ -686,6 +686,9 @@ static int arc_emac_tx(struct sk_buff *skb, struct net_device *ndev)
>>  
>>         skb_tx_timestamp(skb);
>>  
>> +       /* Make sure timestamp is set */
>> +       smp_wmb();
> 
> Should be dma_wmb() (see davem's message).
> 
> It's completely unrelated to SMP.
> 

Its also completely unrelated to dma so I doubt that this is what davem meant.
As far as I understood he was referring to the dma descriptor.

Lino