ieee1394: fix to ether1394_tx in ether1394.c

This patch fixes a problem that occurs when packets cannot be sent across
the ieee1394 bus and we return NETDEV_TX_BUSY in the net driver "hard start
xmit" routine ether1394_tx. When we return NETDEV_TX_BUSY the stack will
call ether1394_tx again with the same skb. So we need to restore the header
to look like it did before we munged it for xmit over ieee1394.

[Stefan Richter: changed whitespace, deleted a local variable]

Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>

1 files changed, 15 insertions, 6 deletions

diff --git a/drivers/ieee1394/eth1394.c b/drivers/ieee1394/eth1394.c
index 5f026b5d7857..7c13fb3c167b 100644
--- a/drivers/ieee1394/eth1394.c
+++ b/drivers/ieee1394/eth1394.c
@@ -1565,7 +1565,7 @@ static void ether1394_complete_cb(void *__ptask)
 /* Transmit a packet (called by kernel) */
 static int ether1394_tx(struct sk_buff *skb, struct net_device *dev)
 {
-        struct eth1394hdr *eth;
+        struct eth1394hdr hdr_buf;
         struct eth1394_priv *priv = netdev_priv(dev);
         __be16 proto;
         unsigned long flags;
@@ -1595,16 +1595,17 @@ static int ether1394_tx(struct sk_buff *skb, struct net_device *dev)
         if (!skb)
                 goto fail;
 
-        /* Get rid of the fake eth1394 header, but save a pointer */
-        eth = (struct eth1394hdr *)skb->data;
+        /* Get rid of the fake eth1394 header, but first make a copy.
+         * We might need to rebuild the header on tx failure. */
+        memcpy(&hdr_buf, skb->data, sizeof(hdr_buf));
         skb_pull(skb, ETH1394_HLEN);
 
-        proto = eth->h_proto;
+        proto = hdr_buf.h_proto;
         dg_size = skb->len;
 
         /* Set the transmission type for the packet.  ARP packets and IP
          * broadcast packets are sent via GASP. */
-        if (memcmp(eth->h_dest, dev->broadcast, ETH1394_ALEN) == 0 ||
+        if (memcmp(hdr_buf.h_dest, dev->broadcast, ETH1394_ALEN) == 0 ||
             proto == htons(ETH_P_ARP) ||
             (proto == htons(ETH_P_IP) &&
              IN_MULTICAST(ntohl(ip_hdr(skb)->daddr)))) {
@@ -1616,7 +1617,7 @@ static int ether1394_tx(struct sk_buff *skb, struct net_device *dev)
                 if (max_payload < dg_size + hdr_type_len[ETH1394_HDR_LF_UF])
                         priv->bc_dgl++;
         } else {
-                __be64 guid = get_unaligned((u64 *)eth->h_dest);
+                __be64 guid = get_unaligned((u64 *)hdr_buf.h_dest);
 
                 node = eth1394_find_node_guid(&priv->ip_node_list,
                                               be64_to_cpu(guid));
@@ -1673,6 +1674,14 @@ static int ether1394_tx(struct sk_buff *skb, struct net_device *dev)
                 if (dest_node == (LOCAL_BUS | ALL_NODES))
                         goto fail;
 
+                /* At this point we want to restore the packet.  When we return
+                 * here with NETDEV_TX_BUSY we will get another entrance in this
+                 * routine with the same skb and we need it to look the same.
+                 * So we pull 4 more bytes, then build the header again. */
+                skb_pull(skb, 4);
+                ether1394_header(skb, dev, ntohs(hdr_buf.h_proto),
+                                 hdr_buf.h_dest, NULL, 0);
+
                 /* Most failures of ether1394_send_packet are recoverable. */
                 netif_stop_queue(dev);
                 priv->wake_node = dest_node;