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

[net-next-2.6.git] / net / dccp / ackvec.h

diff --git a/net/dccp/ackvec.h b/net/dccp/ackvec.h
index 3e894a0173a76817ec52214fecfe7af9c8accf98..23880be8fc29711752e42e564364f97dd9bc729e 100644 (file)
--- a/net/dccp/ackvec.h
+++ b/net/dccp/ackvec.h
@@ -21,6 +21,7 @@
  * the maximum size of a single Ack Vector. Setting %DCCPAV_NUM_ACKVECS to 1
  * will be sufficient for most cases of low Ack Ratios, using a value of 2 gives
  * more headroom if Ack Ratio is higher or when the sender acknowledges slowly.
+ * The maximum value is bounded by the u16 types for indices and functions.
  */
 #define DCCPAV_NUM_ACKVECS     2
 #define DCCPAV_MAX_ACKVEC_LEN  (DCCP_SINGLE_OPT_MAXLEN * DCCPAV_NUM_ACKVECS)
@@ -55,8 +56,10 @@ static inline u8 dccp_ackvec_state(const u8 *cell)
  * @av_buf_head:   head index; begin of live portion in @av_buf
  * @av_buf_tail:   tail index; first index _after_ the live portion in @av_buf
  * @av_buf_ackno:  highest seqno of acknowledgeable packet recorded in @av_buf
+ * @av_tail_ackno: lowest  seqno of acknowledgeable packet recorded in @av_buf
  * @av_buf_nonce:  ECN nonce sums, each covering subsequent segments of up to
  *                %DCCP_SINGLE_OPT_MAXLEN cells in the live portion of @av_buf
+ * @av_overflow:   if 1 then buf_head == buf_tail indicates buffer wraparound
  * @av_records:           list of %dccp_ackvec_record (Ack Vectors sent previously)
  * @av_veclen:    length of the live portion of @av_buf
  */
@@ -65,7 +68,9 @@ struct dccp_ackvec {
        u16                     av_buf_head;
        u16                     av_buf_tail;
        u64                     av_buf_ackno:48;
+       u64                     av_tail_ackno:48;
        bool                    av_buf_nonce[DCCPAV_NUM_ACKVECS];
+       u8                      av_overflow:1;
        struct list_head        av_records;
        u16                     av_vec_len;
 };
@@ -112,9 +117,10 @@ extern int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
                             const u8 *value, const u8 len);
 
 extern int  dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 sum);
+extern u16  dccp_ackvec_buflen(const struct dccp_ackvec *av);
 
-static inline int dccp_ackvec_pending(const struct dccp_ackvec *av)
+static inline bool dccp_ackvec_is_empty(const struct dccp_ackvec *av)
 {
-       return av->av_vec_len;
+       return av->av_overflow == 0 && av->av_buf_head == av->av_buf_tail;
 }
 #endif /* _ACKVEC_H */