From 018c5bba052b3a383d83cf0c756da0e7bc748397 Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Fri, 15 Nov 2013 21:11:16 -0500 Subject: [PATCH] net: Handle CHECKSUM_COMPLETE more adequately in pskb_trim_rcsum(). Currently pskb_trim_rcsum() just balks on CHECKSUM_COMPLETE packets and remarks them as CHECKSUM_NONE, forcing a software checksum validation later. We have all of the mechanics available to fixup the skb->csum value, even for complicated fragmented packets, via the helpers skb_checksum() and csum_sub(). So just use them. Based upon a suggestion by Herbert Xu. Signed-off-by: David S. Miller --- include/linux/skbuff.h | 39 +++++++++++++++++++++------------------ 1 file changed, 21 insertions(+), 18 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 215b5ea1cb30..bec1cc7d5e3c 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -2263,24 +2263,6 @@ static inline void skb_postpull_rcsum(struct sk_buff *skb, unsigned char *skb_pull_rcsum(struct sk_buff *skb, unsigned int len); -/** - * pskb_trim_rcsum - trim received skb and update checksum - * @skb: buffer to trim - * @len: new length - * - * This is exactly the same as pskb_trim except that it ensures the - * checksum of received packets are still valid after the operation. - */ - -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); -} - #define skb_queue_walk(queue, skb) \ for (skb = (queue)->next; \ skb != (struct sk_buff *)(queue); \ @@ -2378,6 +2360,27 @@ __wsum __skb_checksum(const struct sk_buff *skb, int offset, int len, __wsum skb_checksum(const struct sk_buff *skb, int offset, int len, __wsum csum); +/** + * pskb_trim_rcsum - trim received skb and update checksum + * @skb: buffer to trim + * @len: new length + * + * This is exactly the same as pskb_trim except that it ensures the + * checksum of received packets are still valid after the operation. + */ + +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) { + __wsum adj = skb_checksum(skb, len, skb->len - len, 0); + + skb->csum = csum_sub(skb->csum, adj); + } + return __pskb_trim(skb, len); +} + static inline void *skb_header_pointer(const struct sk_buff *skb, int offset, int len, void *buffer) { -- 2.39.2