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dccp ccid-2: Remove old infrastructure
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This removes
 * functions for which updates have been provided in the preceding patches and
 * the @av_vec_len field - it is no longer necessary since the buffer length is
   now always computed dynamically;
 * conditional debugging code (CONFIG_IP_DCCP_ACKVEC).

The reason for removing the conditional debugging code is that Ack Vectors are 
an almost inevitable necessity - RFC 4341 says that for CCID-2, Ack Vectors must
be used. Furthermore, the code would be only interesting for coding - after some 
extensive testing with this patch set, having the debug code around is no longer
of real help.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
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Gerrit Renker committed Sep 4, 2008
1 parent c2f4207 commit 5a577b4
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Showing 5 changed files with 3 additions and 336 deletions.
3 changes: 0 additions & 3 deletions net/dccp/Kconfig
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Expand Up @@ -25,9 +25,6 @@ config INET_DCCP_DIAG
def_tristate y if (IP_DCCP = y && INET_DIAG = y)
def_tristate m

config IP_DCCP_ACKVEC
bool

source "net/dccp/ccids/Kconfig"

menu "DCCP Kernel Hacking"
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5 changes: 2 additions & 3 deletions net/dccp/Makefile
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@@ -1,15 +1,14 @@
obj-$(CONFIG_IP_DCCP) += dccp.o dccp_ipv4.o

dccp-y := ccid.o feat.o input.o minisocks.o options.o output.o proto.o timer.o
dccp-y := ccid.o feat.o input.o minisocks.o options.o \
output.o proto.o timer.o ackvec.o

dccp_ipv4-y := ipv4.o

# build dccp_ipv6 as module whenever either IPv6 or DCCP is a module
obj-$(subst y,$(CONFIG_IP_DCCP),$(CONFIG_IPV6)) += dccp_ipv6.o
dccp_ipv6-y := ipv6.o

dccp-$(CONFIG_IP_DCCP_ACKVEC) += ackvec.o

obj-$(CONFIG_INET_DCCP_DIAG) += dccp_diag.o
obj-$(CONFIG_NET_DCCPPROBE) += dccp_probe.o

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251 changes: 0 additions & 251 deletions net/dccp/ackvec.c
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Expand Up @@ -9,18 +9,10 @@
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; version 2 of the License;
*/

#include "ackvec.h"
#include "dccp.h"

#include <linux/init.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/slab.h>

#include <net/sock.h>

static struct kmem_cache *dccp_ackvec_slab;
static struct kmem_cache *dccp_ackvec_record_slab;

Expand Down Expand Up @@ -281,249 +273,6 @@ void dccp_ackvec_input(struct dccp_ackvec *av, struct sk_buff *skb)
}
}

/*
* If several packets are missing, the HC-Receiver may prefer to enter multiple
* bytes with run length 0, rather than a single byte with a larger run length;
* this simplifies table updates if one of the missing packets arrives.
*/
static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av,
const unsigned int packets,
const unsigned char state)
{
unsigned int gap;
long new_head;

if (av->av_vec_len + packets > DCCPAV_MAX_ACKVEC_LEN)
return -ENOBUFS;

gap = packets - 1;
new_head = av->av_buf_head - packets;

if (new_head < 0) {
if (gap > 0) {
memset(av->av_buf, DCCPAV_NOT_RECEIVED,
gap + new_head + 1);
gap = -new_head;
}
new_head += DCCPAV_MAX_ACKVEC_LEN;
}

av->av_buf_head = new_head;

if (gap > 0)
memset(av->av_buf + av->av_buf_head + 1,
DCCPAV_NOT_RECEIVED, gap);

av->av_buf[av->av_buf_head] = state;
av->av_vec_len += packets;
return 0;
}

/*
* Implements the RFC 4340, Appendix A
*/
int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
const u64 ackno, const u8 state)
{
u8 *cur_head = av->av_buf + av->av_buf_head,
*buf_end = av->av_buf + DCCPAV_MAX_ACKVEC_LEN;
/*
* Check at the right places if the buffer is full, if it is, tell the
* caller to start dropping packets till the HC-Sender acks our ACK
* vectors, when we will free up space in av_buf.
*
* We may well decide to do buffer compression, etc, but for now lets
* just drop.
*
* From Appendix A.1.1 (`New Packets'):
*
* Of course, the circular buffer may overflow, either when the
* HC-Sender is sending data at a very high rate, when the
* HC-Receiver's acknowledgements are not reaching the HC-Sender,
* or when the HC-Sender is forgetting to acknowledge those acks
* (so the HC-Receiver is unable to clean up old state). In this
* case, the HC-Receiver should either compress the buffer (by
* increasing run lengths when possible), transfer its state to
* a larger buffer, or, as a last resort, drop all received
* packets, without processing them whatsoever, until its buffer
* shrinks again.
*/

/* See if this is the first ackno being inserted */
if (av->av_vec_len == 0) {
*cur_head = state;
av->av_vec_len = 1;
} else if (after48(ackno, av->av_buf_ackno)) {
const u64 delta = dccp_delta_seqno(av->av_buf_ackno, ackno);

/*
* Look if the state of this packet is the same as the
* previous ackno and if so if we can bump the head len.
*/
if (delta == 1 && dccp_ackvec_state(cur_head) == state &&
dccp_ackvec_runlen(cur_head) < DCCPAV_MAX_RUNLEN)
*cur_head += 1;
else if (dccp_ackvec_set_buf_head_state(av, delta, state))
return -ENOBUFS;
} else {
/*
* A.1.2. Old Packets
*
* When a packet with Sequence Number S <= buf_ackno
* arrives, the HC-Receiver will scan the table for
* the byte corresponding to S. (Indexing structures
* could reduce the complexity of this scan.)
*/
u64 delta = dccp_delta_seqno(ackno, av->av_buf_ackno);

while (1) {
const u8 len = dccp_ackvec_runlen(cur_head);
/*
* valid packets not yet in av_buf have a reserved
* entry, with a len equal to 0.
*/
if (*cur_head == DCCPAV_NOT_RECEIVED && delta == 0) {
dccp_pr_debug("Found %llu reserved seat!\n",
(unsigned long long)ackno);
*cur_head = state;
goto out;
}
/* len == 0 means one packet */
if (delta < len + 1)
goto out_duplicate;

delta -= len + 1;
if (++cur_head == buf_end)
cur_head = av->av_buf;
}
}

av->av_buf_ackno = ackno;
out:
return 0;

out_duplicate:
/* Duplicate packet */
dccp_pr_debug("Received a dup or already considered lost "
"packet: %llu\n", (unsigned long long)ackno);
return -EILSEQ;
}

static void dccp_ackvec_throw_record(struct dccp_ackvec *av,
struct dccp_ackvec_record *avr)
{
struct dccp_ackvec_record *next;

/* sort out vector length */
if (av->av_buf_head <= avr->avr_ack_ptr)
av->av_vec_len = avr->avr_ack_ptr - av->av_buf_head;
else
av->av_vec_len = DCCPAV_MAX_ACKVEC_LEN - 1 -
av->av_buf_head + avr->avr_ack_ptr;

/* free records */
list_for_each_entry_safe_from(avr, next, &av->av_records, avr_node) {
list_del(&avr->avr_node);
kmem_cache_free(dccp_ackvec_record_slab, avr);
}
}

void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk,
const u64 ackno)
{
struct dccp_ackvec_record *avr;

/*
* If we traverse backwards, it should be faster when we have large
* windows. We will be receiving ACKs for stuff we sent a while back
* -sorbo.
*/
list_for_each_entry_reverse(avr, &av->av_records, avr_node) {
if (ackno == avr->avr_ack_seqno) {
dccp_pr_debug("%s ACK packet 0, len=%d, ack_seqno=%llu, "
"ack_ackno=%llu, ACKED!\n",
dccp_role(sk), avr->avr_ack_runlen,
(unsigned long long)avr->avr_ack_seqno,
(unsigned long long)avr->avr_ack_ackno);
dccp_ackvec_throw_record(av, avr);
break;
} else if (avr->avr_ack_seqno > ackno)
break; /* old news */
}
}

static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av,
struct sock *sk, u64 *ackno,
const unsigned char len,
const unsigned char *vector)
{
unsigned char i;
struct dccp_ackvec_record *avr;

/* Check if we actually sent an ACK vector */
if (list_empty(&av->av_records))
return;

i = len;
/*
* XXX
* I think it might be more efficient to work backwards. See comment on
* rcv_ackno. -sorbo.
*/
avr = list_entry(av->av_records.next, struct dccp_ackvec_record, avr_node);
while (i--) {
const u8 rl = dccp_ackvec_runlen(vector);
u64 ackno_end_rl;

dccp_set_seqno(&ackno_end_rl, *ackno - rl);

/*
* If our AVR sequence number is greater than the ack, go
* forward in the AVR list until it is not so.
*/
list_for_each_entry_from(avr, &av->av_records, avr_node) {
if (!after48(avr->avr_ack_seqno, *ackno))
goto found;
}
/* End of the av_records list, not found, exit */
break;
found:
if (between48(avr->avr_ack_seqno, ackno_end_rl, *ackno)) {
if (dccp_ackvec_state(vector) != DCCPAV_NOT_RECEIVED) {
dccp_pr_debug("%s ACK vector 0, len=%d, "
"ack_seqno=%llu, ack_ackno=%llu, "
"ACKED!\n",
dccp_role(sk), len,
(unsigned long long)
avr->avr_ack_seqno,
(unsigned long long)
avr->avr_ack_ackno);
dccp_ackvec_throw_record(av, avr);
break;
}
/*
* If it wasn't received, continue scanning... we might
* find another one.
*/
}

dccp_set_seqno(ackno, ackno_end_rl - 1);
++vector;
}
}

int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
u64 *ackno, const u8 opt, const u8 *value, const u8 len)
{
if (len > DCCP_SINGLE_OPT_MAXLEN)
return -1;

/* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */
dccp_ackvec_check_rcv_ackvector(dccp_sk(sk)->dccps_hc_rx_ackvec, sk,
ackno, len, value);
return 0;
}

/**
* dccp_ackvec_clear_state - Perform house-keeping / garbage-collection
* This routine is called when the peer acknowledges the receipt of Ack Vectors
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