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
---
include/net/checksum.h | 2 ++
net/core/utils.c | 13 +
2 files changed, 15 insertions(+)
diff --git a/include/net/checksum.h b/include/net/checksum.h
index 2d1d73c..0e0c987 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,
int pseudohdr);
+void inet_proto_csum_replace_by_diff(__sum16 *sum, struct sk_buff *skb,
+__wsum diff, int 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 a7732a0..89ccfb1 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, int 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;
--
1.8.1
--
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