tg3: Cleanup transmit error path
Matt Carlson [Thu, 19 May 2011 12:12:45 +0000 (12:12 +0000)]
This patch consolidates the skb cleanup code into a function named
tg3_skb_error_unmap().  The modification addresses a long-standing bug
where pci_unmap_single() was incorrectly being called instead of
pci_unmap_page() in tigon3_dma_hwbug_workaround().

Signed-off-by: Matt Carlson <mcarlson@broadcom.com>
Reviewed-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/tg3.c

index 4c44168..b2b1ba1 100644 (file)
@@ -5758,16 +5758,39 @@ static void tg3_set_txd(struct tg3_napi *tnapi, int entry,
        txd->vlan_tag = vlan_tag << TXD_VLAN_TAG_SHIFT;
 }
 
+static void tg3_skb_error_unmap(struct tg3_napi *tnapi,
+                               struct sk_buff *skb, int last)
+{
+       int i;
+       u32 entry = tnapi->tx_prod;
+       struct ring_info *txb = &tnapi->tx_buffers[entry];
+
+       pci_unmap_single(tnapi->tp->pdev,
+                        dma_unmap_addr(txb, mapping),
+                        skb_headlen(skb),
+                        PCI_DMA_TODEVICE);
+       for (i = 0; i <= last; i++) {
+               skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
+
+               entry = NEXT_TX(entry);
+               txb = &tnapi->tx_buffers[entry];
+
+               pci_unmap_page(tnapi->tp->pdev,
+                              dma_unmap_addr(txb, mapping),
+                              frag->size, PCI_DMA_TODEVICE);
+       }
+}
+
 /* Workaround 4GB and 40-bit hardware DMA bugs. */
 static int tigon3_dma_hwbug_workaround(struct tg3_napi *tnapi,
-                                      struct sk_buff *skb, u32 last_plus_one,
-                                      u32 *start, u32 base_flags, u32 mss)
+                                      struct sk_buff *skb,
+                                      u32 base_flags, u32 mss)
 {
        struct tg3 *tp = tnapi->tp;
        struct sk_buff *new_skb;
        dma_addr_t new_addr = 0;
-       u32 entry = *start;
-       int i, ret = 0;
+       u32 entry = tnapi->tx_prod;
+       int ret = 0;
 
        if (GET_ASIC_REV(tp->pci_chip_rev_id) != ASIC_REV_5701)
                new_skb = skb_copy(skb, GFP_ATOMIC);
@@ -5783,14 +5806,12 @@ static int tigon3_dma_hwbug_workaround(struct tg3_napi *tnapi,
                ret = -1;
        } else {
                /* New SKB is guaranteed to be linear. */
-               entry = *start;
                new_addr = pci_map_single(tp->pdev, new_skb->data, new_skb->len,
                                          PCI_DMA_TODEVICE);
                /* Make sure the mapping succeeded */
                if (pci_dma_mapping_error(tp->pdev, new_addr)) {
                        ret = -1;
                        dev_kfree_skb(new_skb);
-                       new_skb = NULL;
 
                /* Make sure new skb does not cross any 4G boundaries.
                 * Drop the packet if it does.
@@ -5801,39 +5822,16 @@ static int tigon3_dma_hwbug_workaround(struct tg3_napi *tnapi,
                                         PCI_DMA_TODEVICE);
                        ret = -1;
                        dev_kfree_skb(new_skb);
-                       new_skb = NULL;
                } else {
+                       tnapi->tx_buffers[entry].skb = new_skb;
+                       dma_unmap_addr_set(&tnapi->tx_buffers[entry],
+                                          mapping, new_addr);
+
                        tg3_set_txd(tnapi, entry, new_addr, new_skb->len,
                                    base_flags, 1 | (mss << 1));
-                       *start = NEXT_TX(entry);
                }
        }
 
-       /* Now clean up the sw ring entries. */
-       i = 0;
-       while (entry != last_plus_one) {
-               int len;
-
-               if (i == 0)
-                       len = skb_headlen(skb);
-               else
-                       len = skb_shinfo(skb)->frags[i-1].size;
-
-               pci_unmap_single(tp->pdev,
-                                dma_unmap_addr(&tnapi->tx_buffers[entry],
-                                               mapping),
-                                len, PCI_DMA_TODEVICE);
-               if (i == 0) {
-                       tnapi->tx_buffers[entry].skb = new_skb;
-                       dma_unmap_addr_set(&tnapi->tx_buffers[entry], mapping,
-                                          new_addr);
-               } else {
-                       tnapi->tx_buffers[entry].skb = NULL;
-               }
-               entry = NEXT_TX(entry);
-               i++;
-       }
-
        dev_kfree_skb(skb);
 
        return ret;
@@ -5889,11 +5887,11 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
 {
        struct tg3 *tp = netdev_priv(dev);
        u32 len, entry, base_flags, mss;
-       int would_hit_hwbug;
+       int i = -1, would_hit_hwbug;
        dma_addr_t mapping;
        struct tg3_napi *tnapi;
        struct netdev_queue *txq;
-       unsigned int i, last;
+       unsigned int last;
 
        txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
        tnapi = &tp->napi[skb_get_queue_mapping(skb)];
@@ -6074,20 +6072,15 @@ static netdev_tx_t tg3_start_xmit(struct sk_buff *skb, struct net_device *dev)
        }
 
        if (would_hit_hwbug) {
-               u32 last_plus_one = entry;
-               u32 start;
-
-               start = entry - 1 - skb_shinfo(skb)->nr_frags;
-               start &= (TG3_TX_RING_SIZE - 1);
+               tg3_skb_error_unmap(tnapi, skb, i);
 
                /* If the workaround fails due to memory/mapping
                 * failure, silently drop this packet.
                 */
-               if (tigon3_dma_hwbug_workaround(tnapi, skb, last_plus_one,
-                                               &start, base_flags, mss))
+               if (tigon3_dma_hwbug_workaround(tnapi, skb, base_flags, mss))
                        goto out_unlock;
 
-               entry = start;
+               entry = NEXT_TX(tnapi->tx_prod);
        }
 
        /* Packets are ready, update Tx producer idx local and on card. */
@@ -6113,24 +6106,9 @@ out_unlock:
        return NETDEV_TX_OK;
 
 dma_error:
-       last = i;
-       entry = tnapi->tx_prod;
-       tnapi->tx_buffers[entry].skb = NULL;
-       pci_unmap_single(tp->pdev,
-                        dma_unmap_addr(&tnapi->tx_buffers[entry], mapping),
-                        skb_headlen(skb),
-                        PCI_DMA_TODEVICE);
-       for (i = 0; i <= last; i++) {
-               skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
-               entry = NEXT_TX(entry);
-
-               pci_unmap_page(tp->pdev,
-                              dma_unmap_addr(&tnapi->tx_buffers[entry],
-                                             mapping),
-                              frag->size, PCI_DMA_TODEVICE);
-       }
-
+       tg3_skb_error_unmap(tnapi, skb, i);
        dev_kfree_skb(skb);
+       tnapi->tx_buffers[tnapi->tx_prod].skb = NULL;
        return NETDEV_TX_OK;
 }