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authorGerrit Renker <gerrit@erg.abdn.ac.uk>2008-12-08 04:19:06 -0500
committerDavid S. Miller <davem@davemloft.net>2008-12-08 04:19:06 -0500
commit6fdd34d43bff8be9bb925b49d87a0ee144d2ab07 (patch)
tree547cf602983db37d573d3d191ac11660f1698e8f /Documentation/networking
parent4098dce5be537a157eed4a326efd464109825b8b (diff)
dccp ccid-2: Phase out the use of boolean Ack Vector sysctl
This removes the use of the sysctl and the minisock variable for the Send Ack Vector feature, as it now is handled fully dynamically via feature negotiation (i.e. when CCID-2 is enabled, Ack Vectors are automatically enabled as per RFC 4341, 4.). Using a sysctl in parallel to this implementation would open the door to crashes, since much of the code relies on tests of the boolean minisock / sysctl variable. Thus, this patch replaces all tests of type if (dccp_msk(sk)->dccpms_send_ack_vector) /* ... */ with if (dp->dccps_hc_rx_ackvec != NULL) /* ... */ The dccps_hc_rx_ackvec is allocated by the dccp_hdlr_ackvec() when feature negotiation concluded that Ack Vectors are to be used on the half-connection. Otherwise, it is NULL (due to dccp_init_sock/dccp_create_openreq_child), so that the test is a valid one. The activation handler for Ack Vectors is called as soon as the feature negotiation has concluded at the * server when the Ack marking the transition RESPOND => OPEN arrives; * client after it has sent its ACK, marking the transition REQUEST => PARTOPEN. Adding the sequence number of the Response packet to the Ack Vector has been removed, since (a) connection establishment implies that the Response has been received; (b) the CCIDs only look at packets received in the (PART)OPEN state, i.e. this entry will always be ignored; (c) it can not be used for anything useful - to detect loss for instance, only packets received after the loss can serve as pseudo-dupacks. There was a FIXME to change the error code when dccp_ackvec_add() fails. I removed this after finding out that: * the check whether ackno < ISN is already made earlier, * this Response is likely the 1st packet with an Ackno that the client gets, * so when dccp_ackvec_add() fails, the reason is likely not a packet error. 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>
Diffstat (limited to 'Documentation/networking')
-rw-r--r--Documentation/networking/dccp.txt3
1 files changed, 0 insertions, 3 deletions
diff --git a/Documentation/networking/dccp.txt b/Documentation/networking/dccp.txt
index 1403745ab406..7a3bb1abb830 100644
--- a/Documentation/networking/dccp.txt
+++ b/Documentation/networking/dccp.txt
@@ -133,9 +133,6 @@ retries2
133 importance for retransmitted acknowledgments and feature negotiation, 133 importance for retransmitted acknowledgments and feature negotiation,
134 data packets are never retransmitted. Analogue of tcp_retries2. 134 data packets are never retransmitted. Analogue of tcp_retries2.
135 135
136send_ackvec = 1
137 Whether or not to send Ack Vector options (sec. 11.5).
138
139tx_ccid = 2 136tx_ccid = 2
140 Default CCID for the sender-receiver half-connection. Depending on the 137 Default CCID for the sender-receiver half-connection. Depending on the
141 choice of CCID, the Send Ack Vector feature is enabled automatically. 138 choice of CCID, the Send Ack Vector feature is enabled automatically.