From 9835fd84990ca253c5b625005717a9be492788c0 Mon Sep 17 00:00:00 2001 From: Inaky Perez-Gonzalez Date: Tue, 29 Sep 2009 16:28:24 -0700 Subject: wimax/i2400m: fix race condition with tcpdump et al tcpdump and friends were not being able to decode packets sent via WiMAX; they had a zero ethernet type, even when the stack was properly sending them to the device with the right type. It happens that the driver was overwriting the (fake) ethernet header for creating the hardware header and that was bitting the cloning used by tcpdump (et al) to look into the packets. Use pkskb_expand_head() [method copied from the e1000 driver] to fix. Thanks to Herbert Xu and Andi Kleen for helping to diagnose and pointing to the right fix. Cc: Herbert Xu Cc: Andi Kleen Signed-off-by: Inaky Perez-Gonzalez --- drivers/net/wimax/i2400m/netdev.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/drivers/net/wimax/i2400m/netdev.c b/drivers/net/wimax/i2400m/netdev.c index fefd794087a..e7d1a51ee3f 100644 --- a/drivers/net/wimax/i2400m/netdev.c +++ b/drivers/net/wimax/i2400m/netdev.c @@ -358,6 +358,20 @@ netdev_tx_t i2400m_hard_start_xmit(struct sk_buff *skb, int result; d_fnstart(3, dev, "(skb %p net_dev %p)\n", skb, net_dev); + if (skb_header_cloned(skb)) { + /* + * Make tcpdump/wireshark happy -- if they are + * running, the skb is cloned and we will overwrite + * the mac fields in i2400m_tx_prep_header. Expand + * seems to fix this... + */ + result = pskb_expand_head(skb, 0, 0, GFP_ATOMIC); + if (result) { + result = NETDEV_TX_BUSY; + goto error_expand; + } + } + if (i2400m->state == I2400M_SS_IDLE) result = i2400m_net_wake_tx(i2400m, net_dev, skb); else @@ -368,10 +382,11 @@ netdev_tx_t i2400m_hard_start_xmit(struct sk_buff *skb, net_dev->stats.tx_packets++; net_dev->stats.tx_bytes += skb->len; } + result = NETDEV_TX_OK; +error_expand: kfree_skb(skb); - - d_fnend(3, dev, "(skb %p net_dev %p)\n", skb, net_dev); - return NETDEV_TX_OK; + d_fnend(3, dev, "(skb %p net_dev %p) = %d\n", skb, net_dev, result); + return result; } -- cgit v1.2.3