dccp: generalise data-loss condition (d196c9a5) · Commits · 戴 / test

This patch generalises the task of determining data loss from RFC 4340, 7.7.1. Let S_A, S_B be sequence numbers such that S_B is "after" S_A, and let N_B be the NDP count of packet S_B. Then, using modulo-2^48 arithmetic, D = S_B - S_A - 1 is an upper bound of the number of lost data packets, D - N_B is an approximation of the number of lost data packets (there are cases where this is not exact). The patch implements this as dccp_loss_count(S_A, S_B, N_B) := max(S_B - S_A - 1 - N_B, 0) Signed-off-by:

Ivo Calado <ivocalado@embedded.ufcg.edu.br> Signed-off-by:

Erivaldo Xavier <desadoc@gmail.com> Signed-off-by:

Leandro Sales <leandroal@gmail.com> Signed-off-by:

Gerrit Renker <gerrit@erg.abdn.ac.uk>

net/dccp/dccp.h

+15 −6

Original line number	Diff line number	Diff line
		@@ -153,18 +153,27 @@ static inline u64 max48(const u64 seq1, const u64 seq2)
		}

		/**
		* dccp_loss_free - Evaluates condition for data loss from RFC 4340, 7.7.1
		* @s1: start sequence number
		* @s2: end sequence number
		* dccp_loss_count - Approximate the number of lost data packets in a burst loss
		* @s1: last known sequence number before the loss ('hole')
		* @s2: first sequence number seen after the 'hole'
		* @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)
		static inline u64 dccp_loss_count(const u64 s1, const u64 s2, const u64 ndp)
		{
		s64 delta = dccp_delta_seqno(s1, s2);

		WARN_ON(delta < 0);
		return (u64)delta <= ndp + 1;
		delta -= ndp + 1;

		return delta > 0 ? delta : 0;
		}

		/**
		* dccp_loss_free - Evaluate condition for data loss from RFC 4340, 7.7.1
		*/
		static inline bool dccp_loss_free(const u64 s1, const u64 s2, const u64 ndp)
		{
		return dccp_loss_count(s1, s2, ndp) == 0;
		}

		enum {

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