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

Shuyu Wei : [...] > I still have a question, is it possible that tx_clean() run > between priv->tx_buff[*txbd_curr].skb = skb and dma_wmb()? A (previous) run can take place after priv->tx_buff[*txbd_curr].skb and before *info = cpu_to_le32(FOR_EMAC | FIRST_OR_LAST_MASK |

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

On Sun, May 15, 2016 at 11:19:53AM +0200, Francois Romieu wrote: > > static void arc_emac_tx_clean(struct net_device *ndev) > { > [...] > for (i = 0; i < TX_BD_NUM; i++) { > unsigned int *txbd_dirty = >txbd_dirty; > struct arc_emac_bd *txbd =

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

Shuyu Wei : [...] > I don't think taking txbd_curr and txbd_dirty only as hints is a good idea. > That could be a big waste, since tx_clean have to go through all the txbds. Sorry if my point was not clear: arc_emac_tx_clean() does not need to change (at least not for the

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

Sorry, the last two lines is wrong, ignore it. I mean I intended to ignore one or two packets. It's just a trade-off for performance, but it doesn't cause any memory leak.

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

On Sat, May 14, 2016 at 10:03:56PM +0200, Francois Romieu wrote: > Shuyu Wei : > > The tail of the ring buffer(txbd_dirty) should never go ahead of the > > head(txbd_curr) or the ring buffer will corrupt. > > > > This is the root cause of racing. > > No (see below). > > It

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

Shuyu Wei : > The tail of the ring buffer(txbd_dirty) should never go ahead of the > head(txbd_curr) or the ring buffer will corrupt. > > This is the root cause of racing. No (see below). It may suffer from some barrier illness though. > Besides, setting the FOR_EMAC flag