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authorTom Herbert <tom@herbertland.com>2015-08-17 23:42:26 +0300
committerDavid S. Miller <davem@davemloft.net>2015-08-18 07:33:06 +0300
commitabc5d1ff3e8f9b4a9d274818459b123e31981dc9 (patch)
treebfe90be833065a4707499800e25c8b65bcbb25b0
parent4b048d6d9d0b0b90e1e94f2393796bbf1fa8df4e (diff)
downloadlinux-abc5d1ff3e8f9b4a9d274818459b123e31981dc9.tar.xz
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>
-rw-r--r--include/net/checksum.h2
-rw-r--r--net/core/utils.c13
2 files changed, 15 insertions, 0 deletions
diff --git a/include/net/checksum.h b/include/net/checksum.h
index 619f3445d57e..9fcaedf994ee 100644
--- a/include/net/checksum.h
+++ b/include/net/checksum.h
@@ -144,6 +144,8 @@ void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
void inet_proto_csum_replace16(__sum16 *sum, struct sk_buff *skb,
const __be32 *from, const __be32 *to,
bool pseudohdr);
+void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb,
+ __wsum diff, bool pseudohdr);
static inline void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
__be16 from, __be16 to,
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;