From abc5d1ff3e8f9b4a9d274818459b123e31981dc9 Mon Sep 17 00:00:00 2001 From: Tom Herbert Date: Mon, 17 Aug 2015 13:42:26 -0700 Subject: net: Add inet_proto_csum_replace_by_diff utility function This function updates a checksum field value and skb->csum based on a value which is the difference between the old and new checksum. Signed-off-by: Tom Herbert Signed-off-by: David S. Miller --- net/core/utils.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'net') diff --git a/net/core/utils.c b/net/core/utils.c index cd7d202f340e..3dffce953c39 100644 --- a/net/core/utils.c +++ b/net/core/utils.c @@ -336,6 +336,19 @@ void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb, } EXPORT_SYMBOL(inet_proto_csum_replace16); +void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb, + __wsum diff, bool pseudohdr) +{ + if (skb->ip_summed != CHECKSUM_PARTIAL) { + *sum = csum_fold(csum_add(diff, ~csum_unfold(*sum))); + if (skb->ip_summed == CHECKSUM_COMPLETE && pseudohdr) + skb->csum = ~csum_add(diff, ~skb->csum); + } else if (pseudohdr) { + *sum = ~csum_fold(csum_add(diff, csum_unfold(*sum))); + } +} +EXPORT_SYMBOL(inet_proto_csum_replace_by_diff); + struct __net_random_once_work { struct work_struct work; struct static_key *key; -- cgit v1.2.3