From 9fc10ed911312c9cec86ef968877cae568770151 Mon Sep 17 00:00:00 2001 From: Jesse Gross Date: Fri, 18 Jun 2010 17:11:44 -0700 Subject: [PATCH] datapath: Don't compute checksums on partial packets. If we are only copying part of a packet to userspace don't bother computing the checksum on that part since it is meaningless. Instead, fall back to the old method of checksumming before copying to ensure the correct result. This was supposed to be part of the previous commit but was left off. --- datapath/datapath.c | 33 +++++++++++++++------------------ 1 file changed, 15 insertions(+), 18 deletions(-) diff --git a/datapath/datapath.c b/datapath/datapath.c index 491f98a5..c715f0ec 100644 --- a/datapath/datapath.c +++ b/datapath/datapath.c @@ -744,16 +744,6 @@ queue_control_packets(struct sk_buff *skb, struct sk_buff_head *queue, nskb = skb->next; skb->next = NULL; -#if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,22) - /* Until 2.6.22, the start of the transport header was - * also the start of data to be checksummed. Linux - * 2.6.22 introduced the csum_start field for this - * purpose, but we should point the transport header to - * it anyway for backward compatibility, as - * dev_queue_xmit() does even in 2.6.28. */ - skb_set_transport_header(skb, skb->csum_start - skb_headroom(skb)); -#endif - err = skb_cow(skb, sizeof *header); if (err) goto err_kfree_skbs; @@ -2201,19 +2191,25 @@ success: retval = 0; if (skb->ip_summed == CHECKSUM_PARTIAL) { - __wsum csum = 0; - int csum_start, csum_offset; + if (copy_bytes == skb->len) { + __wsum csum = 0; + int csum_start, csum_offset; - csum_start = skb_transport_header(skb) - skb->data; #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,22) - csum_offset = skb->csum_offset; + /* Until 2.6.22, the start of the transport header was + * also the start of data to be checksummed. Linux + * 2.6.22 introduced the csum_start field for this + * purpose, but we should point the transport header to + * it anyway for backward compatibility, as + * dev_queue_xmit() does even in 2.6.28. */ + skb_set_transport_header(skb, skb->csum_start - skb_headroom(skb)); + csum_offset = skb->csum_offset; #else - csum_offset = skb->csum; + csum_offset = skb->csum; #endif - if (csum_start + csum_offset + sizeof(__sum16) <= copy_bytes) { + csum_start = skb_transport_header(skb) - skb->data; retval = skb_copy_and_csum_datagram(skb, csum_start, buf + csum_start, copy_bytes - csum_start, &csum); - if (!retval) { __sum16 __user *csump; @@ -2221,7 +2217,8 @@ success: csump = (__sum16 __user *)(buf + csum_start + csum_offset); put_user(csum_fold(csum), csump); } - } + } else + retval = skb_checksum_help(skb); } if (!retval) { -- 2.30.2