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authorTom Herbert <tom@herbertland.com>2015-08-17 13:42:26 -0700
committerDavid S. Miller <davem@davemloft.net>2015-08-17 21:33:06 -0700
commitabc5d1ff3e8f9b4a9d274818459b123e31981dc9 (patch)
treebfe90be833065a4707499800e25c8b65bcbb25b0 /net/core
parent4b048d6d9d0b0b90e1e94f2393796bbf1fa8df4e (diff)
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 <tom@herbertland.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
-rw-r--r--net/core/utils.c13
1 files changed, 13 insertions, 0 deletions
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;

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