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dccp ccid-2: Implementation of circular Ack Vector buffer with overflow handling

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This completes the implementation of a circular buffer for Ack Vectors, by
extending the current (linear array-based) implementation.  The changes are:

 (a) An `overflow' flag to deal with the case of overflow. As before, dynamic
     growth of the buffer will not be supported; but code will be added to deal
     robustly with overflowing Ack Vector buffers.

 (b) A `tail_seqno' field. When naively implementing the algorithm of Appendix A
     in RFC 4340, problems arise whenever subsequent Ack Vector records overlap,
     which can bring the entire run length calculation completely out of synch.
     (This is documented on http://www.erg.abdn.ac.uk/users/gerrit/dccp/notes/\
                                             ack_vectors/tracking_tail_ackno/ .)
 (c) The buffer length is now computed dynamically (i.e. current fill level),
     as the span between head to tail.

As a result, dccp_ackvec_pending() is now simpler - the #ifdef is no longer
necessary since buf_empty is always true when IP_DCCP_ACKVEC is not configured.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
This commit is contained in:
Gerrit Renker
2010-11-10 21:21:35 +01:00
parent 7d87093660
commit b3d14bff12
4 changed files with 50 additions and 12 deletions
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11
net/dccp/dccp.h
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@@ -457,12 +457,15 @@ static inline void dccp_update_gss(struct sock *sk, u64 seq)
dp->dccps_awh = dp->dccps_gss;
}
static inline int dccp_ackvec_pending(const struct sock *sk)
{
return dccp_sk(sk)->dccps_hc_rx_ackvec != NULL &&
!dccp_ackvec_is_empty(dccp_sk(sk)->dccps_hc_rx_ackvec);
}
static inline int dccp_ack_pending(const struct sock *sk)
{
const struct dccp_sock *dp = dccp_sk(sk);
return (dp->dccps_hc_rx_ackvec != NULL &&
dccp_ackvec_pending(dp->dccps_hc_rx_ackvec)) ||
inet_csk_ack_scheduled(sk);
return dccp_ackvec_pending(sk) || inet_csk_ack_scheduled(sk);
}
extern int dccp_feat_finalise_settings(struct dccp_sock *dp);