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authorHerbert Xu <herbert@gondor.apana.org.au>2006-12-15 20:04:33 -0500
committerJeff Garzik <jeff@garzik.org>2006-12-26 16:28:20 -0500
commit683a2aa339f607c8a422835161ceab68b2a5a18a (patch)
tree02dc57eac192826585de7650ef20616dca5abe3c /drivers/net
parent1a63e846a4099e6fbff86a3b112064378515f254 (diff)
e1000: Do not truncate TSO TCP header with 82544 workaround
The e1000 driver has a workaround for 82544 on PCI-X where if the terminating byte of a buffer is at addresses 0-3 mod 8, then 4 bytes are shaved off it and defered to a new segment. This is due to an erratum that could otherwise cause TX hangs. Unfortunately this breaks TSO because it may cause the TCP header to be split over two segments which itself causes TX hangs. The solution is to pull 4 bytes of data up from the next segment rather than pushing 4 bytes off. This ensures the TCP header remains in one piece and works around the PCI-X hang. This patch is based on one from Jesse Brandeburg. This bug has been trigered by both CONFIG_DEBUG_SLAB as well as Xen. Note that the only reason we don't see this normally is because the TCP stack starts writing from the end, i.e., it writes the TCP header first then slaps on the IP header, etc. So the end of the TCP header (skb->tail - 1 here) is always aligned correctly. Had we made the start of the IP header (e.g., IPv6) 8-byte aligned instead, this would happen for normal TCP traffic as well. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Jesse Brandeburg <jesse.brandeburg@intel.com> -- Visit Openswan at http://www.openswan.org/ Email: Herbert Xu ~{PmV>HI~} <herbert@gondor.apana.org.au> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt -- Signed-off-by: Jeff Garzik <jeff@garzik.org>
Diffstat (limited to 'drivers/net')
-rw-r--r--drivers/net/e1000/e1000_main.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/drivers/net/e1000/e1000_main.c b/drivers/net/e1000/e1000_main.c
index 8c4924f1f7e..4c1ff752048 100644
--- a/drivers/net/e1000/e1000_main.c
+++ b/drivers/net/e1000/e1000_main.c
@@ -3318,6 +3318,16 @@ e1000_xmit_frame(struct sk_buff *skb, struct net_device *netdev)
3318 if (skb->data_len && (hdr_len == (skb->len - skb->data_len))) { 3318 if (skb->data_len && (hdr_len == (skb->len - skb->data_len))) {
3319 switch (adapter->hw.mac_type) { 3319 switch (adapter->hw.mac_type) {
3320 unsigned int pull_size; 3320 unsigned int pull_size;
3321 case e1000_82544:
3322 /* Make sure we have room to chop off 4 bytes,
3323 * and that the end alignment will work out to
3324 * this hardware's requirements
3325 * NOTE: this is a TSO only workaround
3326 * if end byte alignment not correct move us
3327 * into the next dword */
3328 if ((unsigned long)(skb->tail - 1) & 4)
3329 break;
3330 /* fall through */
3321 case e1000_82571: 3331 case e1000_82571:
3322 case e1000_82572: 3332 case e1000_82572:
3323 case e1000_82573: 3333 case e1000_82573: