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Message-ID: <4ACB1B95.4090701@gmail.com>
Date: Tue, 06 Oct 2009 12:27:33 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: Giuseppe CAVALLARO <peppe.cavallaro@...com>
CC: netdev@...r.kernel.org
Subject: Re: [PATCH] net: add support for STMicroelectronics Ethernet controllers.
Giuseppe CAVALLARO a écrit :
> +static int stmmac_sw_tso(struct stmmac_priv *priv, struct sk_buff *skb)
> +{
> + struct sk_buff *segs, *curr_skb;
> + int gso_segs = skb_shinfo(skb)->gso_segs;
> +
> + /* Estimate the number of fragments in the worst case */
> + if (unlikely(stmmac_tx_avail(priv) < gso_segs)) {
> + netif_stop_queue(priv->dev);
> + TX_DBG(KERN_ERR "%s: TSO BUG! Tx Ring full when queue awake\n",
> + __func__);
> + if (stmmac_tx_avail(priv) < gso_segs)
> + return NETDEV_TX_BUSY;
> +
> + netif_wake_queue(priv->dev);
> + }
> + TX_DBG("\tstmmac_sw_tso: segmenting: skb %p (len %d)\n",
> + skb, skb->len);
> +
> + segs = skb_gso_segment(skb, priv->dev->features & ~NETIF_F_TSO);
> + if (unlikely(IS_ERR(segs)))
> + goto sw_tso_end;
> +
> + do {
> + curr_skb = segs;
> + segs = segs->next;
> + TX_DBG("\t\tcurrent skb->len: %d, *curr %p,"
> + "*next %p\n", curr_skb->len, curr_skb, segs);
> + curr_skb->next = NULL;
> + stmmac_xmit(curr_skb, priv->dev);
> + } while (segs);
> +
> +sw_tso_end:
> + dev_kfree_skb(skb);
> + return NETDEV_TX_OK;
> +}
So stmmac_sw_tso() calls stmmac_xmit() for each seg skb.
But stmmac_sw_tso() was called from stmmac_xmit(),
with priv->tx_lock locked, so I suspect something is wrong.
> +/**
> + * stmmac_xmit:
> + * @skb : the socket buffer
> + * @dev : device pointer
> + * Description : Tx entry point of the driver.
> + */
> +static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
> +{
...
> + if (unlikely(!spin_trylock_irqsave(&priv->tx_lock, flags)))
> + return NETDEV_TX_LOCKED;
...
> + if (unlikely(skb_is_gso(skb))) {
> + ret = stmmac_sw_tso(priv, skb);
> + goto end_xmit;
> + }
> +
Also please change various
+ mac = kmalloc(sizeof(const struct mac_device_info), GFP_KERNEL);
+ memset(mac, 0, sizeof(struct mac_device_info));
+
+ mac = kmalloc(sizeof(const struct mac_device_info), GFP_KERNEL);
+ memset(mac, 0, sizeof(struct mac_device_info));
+
to use kzalloc(), and of course, you should check kmalloc()/kzalloc() dont return NULL !
Also :
+static int stmmac_clean_tx(struct net_device *dev)
+{
+ struct stmmac_priv *priv = netdev_priv(dev);
+ unsigned int txsize = priv->dma_tx_size;
+ unsigned long ioaddr = dev->base_addr;
+ unsigned int entry = priv->dirty_tx % txsize;
+ unsigned int count = 0;
+
+ spin_lock(&priv->tx_lock);
+ while (priv->dirty_tx != priv->cur_tx) {
+ int last;
+ struct sk_buff *skb = priv->tx_skbuff[entry];
+ struct dma_desc *p = priv->dma_tx + entry;
+
+ if (priv->mac_type->ops->get_tx_owner(p))
+ break;
+
+ count++;
+
+ /* verify tx error by looking at the last segment */
+ last = priv->mac_type->ops->get_tx_ls(p);
+ if (likely(last)) {
+ int tx_error =
+ priv->mac_type->ops->tx_status(&dev->stats,
+ &priv->xstats,
+ p, ioaddr);
+ if (likely(tx_error == 0)) {
+ dev->stats.tx_packets++;
+ priv->xstats.tx_pkt_n++;
+ } else
+ dev->stats.tx_errors++;
+ }
+ DBG(intr, DEBUG, "stmmac_tx: curr %d, dirty %d\n",
+ priv->cur_tx, priv->dirty_tx);
+
+ if (likely(p->des2))
+ dma_unmap_single(priv->device, p->des2,
+ priv->mac_type->ops->get_tx_len(p),
+ DMA_TO_DEVICE);
+ if (unlikely(p->des3))
+ p->des3 = 0;
+
+ if (skb != NULL) {
+ /*
+ * If there's room in the queue (limit it to size)
+ * we add this skb back into the pool,
+ * if it's the right size.
+ */
+ if ((skb_queue_len(&priv->rx_recycle) <
+ priv->dma_rx_size) &&
+ skb_recycle_check(skb, priv->dma_buf_sz))
+ __skb_queue_head(&priv->rx_recycle, skb);
+ else
+ dev_kfree_skb_any(skb);
Why call dev_kfree_skb_any() here ? From NAPI context it is overkill.
+
+ priv->tx_skbuff[entry] = NULL;
+ }
+
+ priv->mac_type->ops->release_tx_desc(p);
+
+ entry = (++priv->dirty_tx) % txsize;
+ }
+ if (unlikely(netif_queue_stopped(dev) &&
+ stmmac_tx_avail(priv) > (MAX_SKB_FRAGS + 1)))
+ netif_wake_queue(dev);
+
+ spin_unlock(&priv->tx_lock);
+ return count;
+}
static int stmmac_poll(struct napi_struct *napi, int budget)
+{
+ struct stmmac_priv *priv = container_of(napi, struct stmmac_priv, napi);
+ struct net_device *dev = priv->dev;
+ int tx_cleaned = 0, work_done = 0;
+
+ priv->xstats.poll_n++;
+
+ tx_cleaned = stmmac_clean_tx(dev);
+
+ work_done = stmmac_rx(dev, budget);
+
+ if (tx_cleaned)
+ return budget;
Why tx_cleaned is used here to exit early ?
+
+ /* If budget not fully consumed, exit the polling mode */
+ if (work_done < budget) {
+ napi_complete(napi);
+ stmmac_dma_enable_irq_rx(dev->base_addr);
+ }
+ return work_done;
+}
+
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