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

On 21.05.2016 21:47, Francois Romieu wrote:

Shuyu Wei [off-list ref] :
[...]

quoted

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