1 files changed, 15 insertions, 0 deletions
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index 1b2cea244e12..32617e0576cb 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -153,6 +153,21 @@ static inline u64 max48(const u64 seq1, const u64 seq2)
 	return after48(seq1, seq2) ? seq1 : seq2;
 }
 
+/**
+ * dccp_loss_free  -  Evaluates condition for data loss from RFC 4340, 7.7.1
+ * @s1:	 start sequence number
+ * @s2:  end sequence number
+ * @ndp: NDP count on packet with sequence number @s2
+ * Returns true if the sequence range s1...s2 has no data loss.
+ */
+static inline bool dccp_loss_free(const u64 s1, const u64 s2, const u64 ndp)
+{
+	s64 delta = dccp_delta_seqno(s1, s2);
+
+	BUG_TRAP(delta >= 0);
+	return (u64)delta <= ndp + 1;
+}
+
 enum {
 	DCCP_MIB_NUM = 0,
 	DCCP_MIB_ACTIVEOPENS,			/* ActiveOpens */