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Date: Wed, 19 Dec 2007 14:25:48 +0000
From: Gerrit Renker <gerrit@....abdn.ac.uk>
To: acme@...hat.com
Cc: dccp@...r.kernel.org, netdev@...r.kernel.org,
Gerrit Renker <gerrit@....abdn.ac.uk>
Subject: [PATCH 07/14] [ACKVEC]: Unnecessary to parse Ack Vectors when clearing HC-receiver state
This removes code clearing Ack Vector state when it is acknowledged via an
Ack Vector by the peer. That code is redundant, since
* the receiver always puts the full acknowledgment window (groups 2,3 in 11.4.2)
into the Ack Vectors it sends; hence the HC-receiver is only interested in the
highest state that the HC-sender received;
* this means that the acknowledgment number on the (Data)Ack from the HC-sender
is sufficient; and work done in parsing earlier state is not necessary, since
the later state subsumes the earlier one (see also RFC 4340, A.4).
Other (minor) changes:
* uses the suggestion made in the code comment, to traverse from oldest record
to youngest - allowing faster hits when the list is large;
* removed the unused argument variable `sk' from check_rcv_ackno;
* renamed check_rcv_ackno => clear_state, since then it is clearer
what is done by the function (also same name as in A.3 of RFC 4340);
* the variable `ackno' now becomes unused in options.c, and therefore
is now used for other (space-saving) purposes.
Signed-off-by: Gerrit Renker <gerrit@....abdn.ac.uk>
---
net/dccp/ackvec.c | 114 ++++++++++------------------------------------------
net/dccp/ackvec.h | 17 +-------
net/dccp/input.c | 4 +-
net/dccp/options.c | 12 ++----
4 files changed, 30 insertions(+), 117 deletions(-)
--- a/net/dccp/ackvec.h
+++ b/net/dccp/ackvec.h
@@ -102,13 +102,8 @@ extern void dccp_ackvec_free(struct dccp_ackvec *av);
extern int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
const u64 ackno, const u8 state);
-extern void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
- struct sock *sk, const u64 ackno);
-extern int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
- u64 *ackno, const u8 opt,
- const u8 *value, const u8 len);
-
extern int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 sum);
+extern void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno);
static inline int dccp_ackvec_pending(const struct dccp_ackvec *av)
{
@@ -139,18 +134,10 @@ static inline int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk,
return -1;
}
-static inline void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av,
- struct sock *sk, const u64 ackno)
+static inline void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno)
{
}
-static inline int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
- const u64 *ackno, const u8 opt,
- const u8 *value, const u8 len)
-{
- return -1;
-}
-
static inline int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seq, u8 nonce)
{
return -1;
--- a/net/dccp/ackvec.c
+++ b/net/dccp/ackvec.c
@@ -86,6 +86,24 @@ int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seqno, u8 nonce_sum)
return 0;
}
+static struct dccp_ackvec_record *dccp_ackvec_lookup(struct list_head *av_list,
+ const u64 ackno)
+{
+ struct dccp_ackvec_record *avr;
+ /*
+ * Exploit that records are inserted in descending order of sequence
+ * number, start with the oldest record first. If @ackno is `before'
+ * the earliest ack_ackno, the packet is too old (or is a duplicate).
+ */
+ list_for_each_entry_reverse(avr, av_list, avr_node) {
+ if (avr->avr_ack_seqno == ackno)
+ return avr;
+ if (before48(ackno, avr->avr_ack_seqno))
+ break;
+ }
+ return NULL;
+}
+
/*
* 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;
@@ -234,101 +252,13 @@ static void dccp_ackvec_throw_record(struct dccp_ackvec *av,
}
}
-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)
+void dccp_ackvec_clear_state(struct dccp_ackvec *av, const u64 ackno)
{
- 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) !=
- DCCP_ACKVEC_STATE_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;
+ avr = dccp_ackvec_lookup(&av->av_records, ackno);
+ if (avr != NULL)
+ dccp_ackvec_throw_record(av, avr);
}
int __init dccp_ackvec_init(void)
--- a/net/dccp/input.c
+++ b/net/dccp/input.c
@@ -164,8 +164,8 @@ static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
struct dccp_sock *dp = dccp_sk(sk);
if (dp->dccps_hc_rx_ackvec != NULL)
- dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk,
- DCCP_SKB_CB(skb)->dccpd_ack_seq);
+ dccp_ackvec_clear_state(dp->dccps_hc_rx_ackvec,
+ DCCP_SKB_CB(skb)->dccpd_ack_seq);
}
static void dccp_deliver_input_to_ccids(struct sock *sk, struct sk_buff *skb)
--- a/net/dccp/options.c
+++ b/net/dccp/options.c
@@ -138,9 +138,8 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
case DCCPO_ACK_VECTOR_1:
if (dccp_packet_without_ack(skb)) /* RFC 4340, 11.4 */
break;
- if (dp->dccps_hc_rx_ackvec != NULL &&
- dccp_ackvec_parse(sk, skb, &ackno, opt, value, len))
- goto out_invalid_option;
+ dccp_pr_debug("%s Ack Vector (len=%u)\n", dccp_role(sk),
+ len);
break;
case DCCPO_TIMESTAMP:
if (len != 4)
@@ -166,8 +165,7 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
}
dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
dccp_role(sk), ntohl(opt_val),
- (unsigned long long)
- DCCP_SKB_CB(skb)->dccpd_ack_seq);
+ (unsigned long long)ackno);
/* schedule an Ack in case this sender is quiescent */
dccp_schedule_ack(sk);
break;
@@ -181,9 +179,7 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, "
"ackno=%llu", dccp_role(sk),
opt_recv->dccpor_timestamp_echo,
- len + 2,
- (unsigned long long)
- DCCP_SKB_CB(skb)->dccpd_ack_seq);
+ len + 2, (unsigned long long)ackno);
value += 4;
--
1.5.3.GIT
--
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