Messages in this thread Patch in this message | | | Subject | Re: [PATCH 1/3] net: lpc_eth: Replace WARN() trace with simple pr_warn() | From | Eric Dumazet <> | Date | Mon, 11 Jun 2012 10:53:55 +0200 |
| |
On Mon, 2012-06-11 at 10:36 +0200, Roland Stigge wrote:
> I encountered cases where this happened for me on a custom board under > heavy load. > > I discussed this with Kevin Wells, the original driver author. We > identified the case of xmit()'s TX request (from .ndo_start_xmit) with > full TX driver buffers as valid when ethernet is busy. > > But maybe this is wrong. Can you please give me a hint how the net > subsystem makes sure that this doesn't happen under normal circumstances?
When TX ring is about to be filler, driver lpc_eth_hard_start_xmit() calls netif_stop_queue(ndev);
So network stack should not call again lpc_eth_hard_start_xmit().
I would say the bug(s) come from __lpc_handle_xmit(), since it does :
if (netif_queue_stopped(ndev)) netif_wake_queue(ndev);
without making sure some room is available in TX ring.
cumulative patch :
diff --git a/drivers/net/ethernet/nxp/lpc_eth.c b/drivers/net/ethernet/nxp/lpc_eth.c index 8d2666f..59b37c8 100644 --- a/drivers/net/ethernet/nxp/lpc_eth.c +++ b/drivers/net/ethernet/nxp/lpc_eth.c @@ -946,16 +946,16 @@ static void __lpc_handle_xmit(struct net_device *ndev) /* Update stats */ ndev->stats.tx_packets++; ndev->stats.tx_bytes += skb->len; - - /* Free buffer */ - dev_kfree_skb_irq(skb); } + dev_kfree_skb_irq(skb); txcidx = readl(LPC_ENET_TXCONSUMEINDEX(pldat->net_base)); } - if (netif_queue_stopped(ndev)) - netif_wake_queue(ndev); + if (pldat->num_used_tx_buffs <= ENET_TX_DESC/2) { + if (netif_queue_stopped(ndev)) + netif_wake_queue(ndev); + } } static int __lpc_handle_recv(struct net_device *ndev, int budget)
| |