Commit f17a37c9 authored by Gerrit Renker's avatar Gerrit Renker

dccp ccid-2: Ack Vector interface clean-up

This patch brings the Ack Vector interface up to date. Its main purpose is
to lay the basis for the subsequent patches of this set, which will use the
new data structure fields and routines.

There are no real algorithmic changes, rather an adaptation:

 (1) Replaced the static Ack Vector size (2) with a #define so that it can
     be adapted (with low loss / Ack Ratio, a value of 1 works, so 2 seems
     to be sufficient for the moment) and added a solution so that computing
     the ECN nonce will continue to work - even with larger Ack Vectors.

 (2) Replaced the #defines for Ack Vector states with a complete enum.

 (3) Replaced #defines to compute Ack Vector length and state with general
     purpose routines (inlines), and updated code to use these.

 (4) Added a `tail' field (conversion to circular buffer in subsequent patch).

 (5) Updated the (outdated) documentation for Ack Vector struct.

 (6) All sequence number containers now trimmed to 48 bits.

 (7) Removal of unused bits:
     * removed dccpav_ack_nonce from struct dccp_ackvec, since this is already
       redundantly stored in the `dccpavr_ack_nonce' (of Ack Vector record);
     * removed Elapsed Time for Ack Vectors (it was nowhere used);
     * replaced semantics of dccpavr_sent_len with dccpavr_ack_runlen, since
       the code needs to be able to remember the old run length;
     * reduced the de-/allocation routines (redundant / duplicate tests).
Signed-off-by: default avatarGerrit Renker <gerrit@erg.abdn.ac.uk>
parent 973a34aa
This diff is collapsed.
...@@ -3,9 +3,9 @@ ...@@ -3,9 +3,9 @@
/* /*
* net/dccp/ackvec.h * net/dccp/ackvec.h
* *
* An implementation of the DCCP protocol * An implementation of Ack Vectors for the DCCP protocol
* Copyright (c) 2007 University of Aberdeen, Scotland, UK
* Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@mandriva.com> * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@mandriva.com>
*
* This program is free software; you can redistribute it and/or modify it * This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as * under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation. * published by the Free Software Foundation.
...@@ -13,75 +13,84 @@ ...@@ -13,75 +13,84 @@
#include <linux/dccp.h> #include <linux/dccp.h>
#include <linux/compiler.h> #include <linux/compiler.h>
#include <linux/ktime.h>
#include <linux/list.h> #include <linux/list.h>
#include <linux/types.h> #include <linux/types.h>
/* We can spread an ack vector across multiple options */ /*
#define DCCP_MAX_ACKVEC_LEN (DCCP_SINGLE_OPT_MAXLEN * 2) * Ack Vector buffer space is static, in multiples of %DCCP_SINGLE_OPT_MAXLEN,
* 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.
*/
#define DCCPAV_NUM_ACKVECS 2
#define DCCPAV_MAX_ACKVEC_LEN (DCCP_SINGLE_OPT_MAXLEN * DCCPAV_NUM_ACKVECS)
/* Estimated minimum average Ack Vector length - used for updating MPS */ /* Estimated minimum average Ack Vector length - used for updating MPS */
#define DCCPAV_MIN_OPTLEN 16 #define DCCPAV_MIN_OPTLEN 16
#define DCCP_ACKVEC_STATE_RECEIVED 0 enum dccp_ackvec_states {
#define DCCP_ACKVEC_STATE_ECN_MARKED (1 << 6) DCCPAV_RECEIVED = 0x00,
#define DCCP_ACKVEC_STATE_NOT_RECEIVED (3 << 6) DCCPAV_ECN_MARKED = 0x40,
DCCPAV_RESERVED = 0x80,
DCCPAV_NOT_RECEIVED = 0xC0
};
#define DCCPAV_MAX_RUNLEN 0x3F
#define DCCP_ACKVEC_STATE_MASK 0xC0 /* 11000000 */ static inline u8 dccp_ackvec_runlen(const u8 *cell)
#define DCCP_ACKVEC_LEN_MASK 0x3F /* 00111111 */ {
return *cell & DCCPAV_MAX_RUNLEN;
}
/** struct dccp_ackvec - ack vector static inline u8 dccp_ackvec_state(const u8 *cell)
* {
* This data structure is the one defined in RFC 4340, Appendix A. return *cell & ~DCCPAV_MAX_RUNLEN;
* }
* @av_buf_head - circular buffer head
* @av_buf_tail - circular buffer tail /** struct dccp_ackvec - Ack Vector main data structure
* @av_buf_ackno - ack # of the most recent packet acknowledgeable in the
* buffer (i.e. %av_buf_head)
* @av_buf_nonce - the one-bit sum of the ECN Nonces on all packets acked
* by the buffer with State 0
*
* Additionally, the HC-Receiver must keep some information about the
* Ack Vectors it has recently sent. For each packet sent carrying an
* Ack Vector, it remembers four variables:
* *
* @av_records - list of dccp_ackvec_record * This implements a fixed-size circular buffer within an array and is largely
* @av_ack_nonce - the one-bit sum of the ECN Nonces for all State 0. * based on Appendix A of RFC 4340.
* *
* @av_time - the time in usecs * @av_buf: circular buffer storage area
* @av_buf - circular buffer of acknowledgeable packets * @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_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_records: list of %dccp_ackvec_record (Ack Vectors sent previously)
* @av_veclen: length of the live portion of @av_buf
*/ */
struct dccp_ackvec { struct dccp_ackvec {
u64 av_buf_ackno; u8 av_buf[DCCPAV_MAX_ACKVEC_LEN];
struct list_head av_records;
ktime_t av_time;
u16 av_buf_head; u16 av_buf_head;
u16 av_buf_tail;
u64 av_buf_ackno:48;
bool av_buf_nonce[DCCPAV_NUM_ACKVECS];
struct list_head av_records;
u16 av_vec_len; u16 av_vec_len;
u8 av_buf_nonce;
u8 av_ack_nonce;
u8 av_buf[DCCP_MAX_ACKVEC_LEN];
}; };
/** struct dccp_ackvec_record - ack vector record /** struct dccp_ackvec_record - Records information about sent Ack Vectors
* *
* ACK vector record as defined in Appendix A of spec. * These list entries define the additional information which the HC-Receiver
* keeps about recently-sent Ack Vectors; again refer to RFC 4340, Appendix A.
* *
* The list is sorted by avr_ack_seqno * @avr_node: the list node in @av_records
* @avr_ack_seqno: sequence number of the packet the Ack Vector was sent on
* @avr_ack_ackno: the Ack number that this record/Ack Vector refers to
* @avr_ack_ptr: pointer into @av_buf where this record starts
* @avr_ack_runlen: run length of @avr_ack_ptr at the time of sending
* @avr_ack_nonce: the sum of @av_buf_nonce's at the time this record was sent
* *
* @avr_node - node in av_records * The list as a whole is sorted in descending order by @avr_ack_seqno.
* @avr_ack_seqno - sequence number of the packet this record was sent on
* @avr_ack_ackno - sequence number being acknowledged
* @avr_ack_ptr - pointer into av_buf where this record starts
* @avr_ack_nonce - av_ack_nonce at the time this record was sent
* @avr_sent_len - lenght of the record in av_buf
*/ */
struct dccp_ackvec_record { struct dccp_ackvec_record {
struct list_head avr_node; struct list_head avr_node;
u64 avr_ack_seqno; u64 avr_ack_seqno:48;
u64 avr_ack_ackno; u64 avr_ack_ackno:48;
u16 avr_ack_ptr; u16 avr_ack_ptr;
u16 avr_sent_len; u8 avr_ack_runlen;
u8 avr_ack_nonce; u8 avr_ack_nonce:1;
}; };
struct sock; struct sock;
......
...@@ -513,8 +513,7 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) ...@@ -513,8 +513,7 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
&vector, &veclen)) != -1) { &vector, &veclen)) != -1) {
/* go through this ack vector */ /* go through this ack vector */
while (veclen--) { while (veclen--) {
const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK; u64 ackno_end_rl = SUB48(ackno, dccp_ackvec_runlen(vector));
u64 ackno_end_rl = SUB48(ackno, rl);
ccid2_pr_debug("ackvec start:%llu end:%llu\n", ccid2_pr_debug("ackvec start:%llu end:%llu\n",
(unsigned long long)ackno, (unsigned long long)ackno,
...@@ -537,17 +536,15 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb) ...@@ -537,17 +536,15 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
* run length * run length
*/ */
while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) { while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) {
const u8 state = *vector & const u8 state = dccp_ackvec_state(vector);
DCCP_ACKVEC_STATE_MASK;
/* new packet received or marked */ /* new packet received or marked */
if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED && if (state != DCCPAV_NOT_RECEIVED &&
!seqp->ccid2s_acked) { !seqp->ccid2s_acked) {
if (state == if (state == DCCPAV_ECN_MARKED)
DCCP_ACKVEC_STATE_ECN_MARKED) {
ccid2_congestion_event(sk, ccid2_congestion_event(sk,
seqp); seqp);
} else else
ccid2_new_ack(sk, seqp, ccid2_new_ack(sk, seqp,
&maxincr); &maxincr);
......
...@@ -378,8 +378,7 @@ int dccp_rcv_established(struct sock *sk, struct sk_buff *skb, ...@@ -378,8 +378,7 @@ int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
if (dp->dccps_hc_rx_ackvec != NULL && if (dp->dccps_hc_rx_ackvec != NULL &&
dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk, dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
DCCP_SKB_CB(skb)->dccpd_seq, DCCP_SKB_CB(skb)->dccpd_seq, DCCPAV_RECEIVED))
DCCP_ACKVEC_STATE_RECEIVED))
goto discard; goto discard;
dccp_deliver_input_to_ccids(sk, skb); dccp_deliver_input_to_ccids(sk, skb);
...@@ -637,8 +636,7 @@ int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb, ...@@ -637,8 +636,7 @@ int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
if (dp->dccps_hc_rx_ackvec != NULL && if (dp->dccps_hc_rx_ackvec != NULL &&
dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk, dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
DCCP_SKB_CB(skb)->dccpd_seq, DCCP_SKB_CB(skb)->dccpd_seq, DCCPAV_RECEIVED))
DCCP_ACKVEC_STATE_RECEIVED))
goto discard; goto discard;
dccp_deliver_input_to_ccids(sk, skb); dccp_deliver_input_to_ccids(sk, skb);
......
...@@ -340,6 +340,7 @@ static inline int dccp_elapsed_time_len(const u32 elapsed_time) ...@@ -340,6 +340,7 @@ static inline int dccp_elapsed_time_len(const u32 elapsed_time)
return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4; return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
} }
/* FIXME: This function is currently not used anywhere */
int dccp_insert_option_elapsed_time(struct sk_buff *skb, u32 elapsed_time) int dccp_insert_option_elapsed_time(struct sk_buff *skb, u32 elapsed_time)
{ {
const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time); const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
......
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