Re: [PATCH net-next] net: stmmac: add BQL support
From: Florian Fainelli <f.fainelli@gmail.com>
Date: 2014-12-29 07:48:58
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lkml
2014-12-28 6:57 GMT-08:00 Beniamino Galvani [off-list ref]:
Add support for Byte Queue Limits to the STMicro MAC driver. Tested on a Amlogic S805 Cortex-A5 board, where the use of BQL slightly decreases the ping latency from ~10ms to ~3ms when the 100Mbps link is saturated by TCP streams. No difference is observed at 1Gbps. Signed-off-by: Beniamino Galvani <redacted> ---
[snip]
quoted hunk ↗ jump to hunk
priv->dev->stats.tx_errors++;@@ -2049,6 +2057,7 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev) skb_tx_timestamp(skb); priv->hw->dma->enable_dma_transmission(priv->ioaddr); + netdev_sent_queue(dev, skb->len);
You are introducing a potential use after free here in case tx_lock is eliminated one day and your TX reclaim logic kicks in and frees the freshly transmitted SKB, it would be safer to just cache skb->len in a local variable, and use it here.
spin_unlock(&priv->tx_lock);
return NETDEV_TX_OK;-- Florian