From 7fab8b2f0c994decf580027286b97533c8b7f6fd Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 10 Oct 2018 12:30:11 -0700 Subject: net: pskb_trim_rcsum() and CHECKSUM_COMPLETE are friends commit 88078d98d1bb085d72af8437707279e203524fa5 upstream. After working on IP defragmentation lately, I found that some large packets defeat CHECKSUM_COMPLETE optimization because of NIC adding zero paddings on the last (small) fragment. While removing the padding with pskb_trim_rcsum(), we set skb->ip_summed to CHECKSUM_NONE, forcing a full csum validation, even if all prior fragments had CHECKSUM_COMPLETE set. We can instead compute the checksum of the part we are trimming, usually smaller than the part we keep. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings Signed-off-by: Greg Kroah-Hartman --- include/linux/skbuff.h | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'include/linux') diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index aa4753ae1ff2..1e734e221ea3 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -2796,6 +2796,7 @@ static inline unsigned char *skb_push_rcsum(struct sk_buff *skb, return skb->data; } +int pskb_trim_rcsum_slow(struct sk_buff *skb, unsigned int len); /** * pskb_trim_rcsum - trim received skb and update checksum * @skb: buffer to trim @@ -2810,9 +2811,7 @@ static inline int pskb_trim_rcsum(struct sk_buff *skb, unsigned int len) { if (likely(len >= skb->len)) return 0; - if (skb->ip_summed == CHECKSUM_COMPLETE) - skb->ip_summed = CHECKSUM_NONE; - return __pskb_trim(skb, len); + return pskb_trim_rcsum_slow(skb, len); } #define rb_to_skb(rb) rb_entry_safe(rb, struct sk_buff, rbnode) -- cgit v1.2.3