dccp: Remove manual influence on NDP Count feature

Updating the NDP count feature is handled automatically now:
 * for CCID-2 it is disabled, since the code does not use NDP counts;
 * for CCID-3 it is enabled, as NDP counts are used to determine loss lengths.

Allowing the user to change NDP values leads to unpredictable and failing
behaviour, since it is then possible to disable NDP counts even when they
are needed (e.g. in CCID-3).

This means that only those user settings are sensible that agree with the
values for Send NDP Count implied by the choice of CCID. But those settings
are already activated by the feature negotiation (CCID dependency tracking),
hence this form of support is redundant.

At startup the initialisation of the NDP count feature uses the default
value of 0, which is done implicitly by the zeroing-out of the socket when
it is allocated. If the choice of CCID or feature negotiation enables NDP
count, this will then be updated via the NDP activation handler.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/include/linux/dccp.h b/include/linux/dccp.h
index 46daea312d92..60e94438eadd 100644
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -371,14 +371,12 @@ static inline unsigned int dccp_hdr_len(const struct sk_buff *skb)
   *
   * @dccpms_sequence_window - Sequence Window Feature (section 7.5.2)
   * @dccpms_send_ack_vector - Send Ack Vector Feature (section 11.5)
-  * @dccpms_send_ndp_count - Send NDP Count Feature (7.7.2)
   * @dccpms_pending - List of features being negotiated
   * @dccpms_conf -
   */
 struct dccp_minisock {
         __u64                   dccpms_sequence_window;
         __u8                    dccpms_send_ack_vector;
-        __u8                    dccpms_send_ndp_count;
         struct list_head        dccpms_pending;
         struct list_head        dccpms_conf;
 };
@@ -490,6 +488,7 @@ struct dccp_ackvec;
  * @dccps_r_ack_ratio - feature-remote Ack Ratio
  * @dccps_pcslen - sender   partial checksum coverage (via sockopt)
  * @dccps_pcrlen - receiver partial checksum coverage (via sockopt)
+ * @dccps_send_ndp_count - local Send NDP Count feature (7.7.2)
  * @dccps_ndp_count - number of Non Data Packets since last data packet
  * @dccps_mss_cache - current value of MSS (path MTU minus header sizes)
  * @dccps_rate_last - timestamp for rate-limiting DCCP-Sync (RFC 4340, 7.5.4)
@@ -529,6 +528,7 @@ struct dccp_sock {
         __u16                           dccps_r_ack_ratio;
         __u8                            dccps_pcslen:4;
         __u8                            dccps_pcrlen:4;
+        __u8                            dccps_send_ndp_count:1;
         __u64                           dccps_ndp_count:48;
         unsigned long                   dccps_rate_last;
         struct dccp_minisock            dccps_minisock;