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linux-sg2042/net/dccp/ccids/ccid2.c

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/*
* net/dccp/ccids/ccid2.c
*
* Copyright (c) 2005, 2006 Andrea Bittau <a.bittau@cs.ucl.ac.uk>
*
* Changes to meet Linux coding standards, and DCCP infrastructure fixes.
*
* Copyright (c) 2006 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
/*
* This implementation should follow RFC 4341
*/
#include "../ccid.h"
#include "../dccp.h"
#include "ccid2.h"
#ifdef CONFIG_IP_DCCP_CCID2_DEBUG
static int ccid2_debug;
#define ccid2_pr_debug(format, a...) DCCP_PR_DEBUG(ccid2_debug, format, ##a)
static void ccid2_hc_tx_check_sanity(const struct ccid2_hc_tx_sock *hctx)
{
int len = 0;
int pipe = 0;
struct ccid2_seq *seqp = hctx->ccid2hctx_seqh;
/* there is data in the chain */
if (seqp != hctx->ccid2hctx_seqt) {
seqp = seqp->ccid2s_prev;
len++;
if (!seqp->ccid2s_acked)
pipe++;
while (seqp != hctx->ccid2hctx_seqt) {
struct ccid2_seq *prev = seqp->ccid2s_prev;
len++;
if (!prev->ccid2s_acked)
pipe++;
/* packets are sent sequentially */
BUG_ON(dccp_delta_seqno(seqp->ccid2s_seq,
prev->ccid2s_seq ) >= 0);
BUG_ON(time_before(seqp->ccid2s_sent,
prev->ccid2s_sent));
seqp = prev;
}
}
BUG_ON(pipe != hctx->ccid2hctx_pipe);
ccid2_pr_debug("len of chain=%d\n", len);
do {
seqp = seqp->ccid2s_prev;
len++;
} while (seqp != hctx->ccid2hctx_seqh);
ccid2_pr_debug("total len=%d\n", len);
BUG_ON(len != hctx->ccid2hctx_seqbufc * CCID2_SEQBUF_LEN);
}
#else
#define ccid2_pr_debug(format, a...)
#define ccid2_hc_tx_check_sanity(hctx)
#endif
static int ccid2_hc_tx_alloc_seq(struct ccid2_hc_tx_sock *hctx)
{
struct ccid2_seq *seqp;
int i;
/* check if we have space to preserve the pointer to the buffer */
if (hctx->ccid2hctx_seqbufc >= (sizeof(hctx->ccid2hctx_seqbuf) /
sizeof(struct ccid2_seq*)))
return -ENOMEM;
/* allocate buffer and initialize linked list */
seqp = kmalloc(CCID2_SEQBUF_LEN * sizeof(struct ccid2_seq), gfp_any());
if (seqp == NULL)
return -ENOMEM;
for (i = 0; i < (CCID2_SEQBUF_LEN - 1); i++) {
seqp[i].ccid2s_next = &seqp[i + 1];
seqp[i + 1].ccid2s_prev = &seqp[i];
}
seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = seqp;
seqp->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
/* This is the first allocation. Initiate the head and tail. */
if (hctx->ccid2hctx_seqbufc == 0)
hctx->ccid2hctx_seqh = hctx->ccid2hctx_seqt = seqp;
else {
/* link the existing list with the one we just created */
hctx->ccid2hctx_seqh->ccid2s_next = seqp;
seqp->ccid2s_prev = hctx->ccid2hctx_seqh;
hctx->ccid2hctx_seqt->ccid2s_prev = &seqp[CCID2_SEQBUF_LEN - 1];
seqp[CCID2_SEQBUF_LEN - 1].ccid2s_next = hctx->ccid2hctx_seqt;
}
/* store the original pointer to the buffer so we can free it */
hctx->ccid2hctx_seqbuf[hctx->ccid2hctx_seqbufc] = seqp;
hctx->ccid2hctx_seqbufc++;
return 0;
}
static int ccid2_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
{
struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
if (hctx->ccid2hctx_pipe < hctx->ccid2hctx_cwnd)
return 0;
return 1; /* XXX CCID should dequeue when ready instead of polling */
}
static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val)
{
struct dccp_sock *dp = dccp_sk(sk);
u32 max_ratio = DIV_ROUND_UP(ccid2_hc_tx_sk(sk)->ccid2hctx_cwnd, 2);
/*
* Ensure that Ack Ratio does not exceed ceil(cwnd/2), which is (2) from
* RFC 4341, 6.1.2. We ignore the statement that Ack Ratio 2 is always
* acceptable since this causes starvation/deadlock whenever cwnd < 2.
* The same problem arises when Ack Ratio is 0 (ie. Ack Ratio disabled).
*/
if (val == 0 || val > max_ratio) {
DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio);
val = max_ratio;
}
if (val > 0xFFFF) /* RFC 4340, 11.3 */
val = 0xFFFF;
if (val == dp->dccps_l_ack_ratio)
return;
ccid2_pr_debug("changing local ack ratio to %u\n", val);
dp->dccps_l_ack_ratio = val;
}
static void ccid2_change_srtt(struct ccid2_hc_tx_sock *hctx, long val)
{
ccid2_pr_debug("change SRTT to %ld\n", val);
hctx->ccid2hctx_srtt = val;
}
static void ccid2_start_rto_timer(struct sock *sk);
static void ccid2_hc_tx_rto_expire(unsigned long data)
{
struct sock *sk = (struct sock *)data;
struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
long s;
bh_lock_sock(sk);
if (sock_owned_by_user(sk)) {
sk_reset_timer(sk, &hctx->ccid2hctx_rtotimer,
jiffies + HZ / 5);
goto out;
}
ccid2_pr_debug("RTO_EXPIRE\n");
ccid2_hc_tx_check_sanity(hctx);
/* back-off timer */
hctx->ccid2hctx_rto <<= 1;
s = hctx->ccid2hctx_rto / HZ;
if (s > 60)
hctx->ccid2hctx_rto = 60 * HZ;
ccid2_start_rto_timer(sk);
/* adjust pipe, cwnd etc */
hctx->ccid2hctx_ssthresh = hctx->ccid2hctx_cwnd / 2;
if (hctx->ccid2hctx_ssthresh < 2)
hctx->ccid2hctx_ssthresh = 2;
hctx->ccid2hctx_cwnd = 1;
hctx->ccid2hctx_pipe = 0;
/* clear state about stuff we sent */
hctx->ccid2hctx_seqt = hctx->ccid2hctx_seqh;
hctx->ccid2hctx_packets_acked = 0;
/* clear ack ratio state. */
hctx->ccid2hctx_rpseq = 0;
hctx->ccid2hctx_rpdupack = -1;
ccid2_change_l_ack_ratio(sk, 1);
ccid2_hc_tx_check_sanity(hctx);
out:
bh_unlock_sock(sk);
sock_put(sk);
}
static void ccid2_start_rto_timer(struct sock *sk)
{
struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
ccid2_pr_debug("setting RTO timeout=%ld\n", hctx->ccid2hctx_rto);
BUG_ON(timer_pending(&hctx->ccid2hctx_rtotimer));
sk_reset_timer(sk, &hctx->ccid2hctx_rtotimer,
jiffies + hctx->ccid2hctx_rto);
}
static void ccid2_hc_tx_packet_sent(struct sock *sk, int more, unsigned int len)
{
struct dccp_sock *dp = dccp_sk(sk);
struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
struct ccid2_seq *next;
hctx->ccid2hctx_pipe++;
hctx->ccid2hctx_seqh->ccid2s_seq = dp->dccps_gss;
hctx->ccid2hctx_seqh->ccid2s_acked = 0;
hctx->ccid2hctx_seqh->ccid2s_sent = jiffies;
next = hctx->ccid2hctx_seqh->ccid2s_next;
/* check if we need to alloc more space */
if (next == hctx->ccid2hctx_seqt) {
if (ccid2_hc_tx_alloc_seq(hctx)) {
DCCP_CRIT("packet history - out of memory!");
/* FIXME: find a more graceful way to bail out */
return;
}
next = hctx->ccid2hctx_seqh->ccid2s_next;
BUG_ON(next == hctx->ccid2hctx_seqt);
}
hctx->ccid2hctx_seqh = next;
ccid2_pr_debug("cwnd=%d pipe=%d\n", hctx->ccid2hctx_cwnd,
hctx->ccid2hctx_pipe);
/*
* FIXME: The code below is broken and the variables have been removed
* from the socket struct. The `ackloss' variable was always set to 0,
* and with arsent there are several problems:
* (i) it doesn't just count the number of Acks, but all sent packets;
* (ii) it is expressed in # of packets, not # of windows, so the
* comparison below uses the wrong formula: Appendix A of RFC 4341
* comes up with the number K = cwnd / (R^2 - R) of consecutive windows
* of data with no lost or marked Ack packets. If arsent were the # of
* consecutive Acks received without loss, then Ack Ratio needs to be
* decreased by 1 when
* arsent >= K * cwnd / R = cwnd^2 / (R^3 - R^2)
* where cwnd / R is the number of Acks received per window of data
* (cf. RFC 4341, App. A). The problems are that
* - arsent counts other packets as well;
* - the comparison uses a formula different from RFC 4341;
* - computing a cubic/quadratic equation each time is too complicated.
* Hence a different algorithm is needed.
*/
#if 0
/* Ack Ratio. Need to maintain a concept of how many windows we sent */
hctx->ccid2hctx_arsent++;
/* We had an ack loss in this window... */
if (hctx->ccid2hctx_ackloss) {
if (hctx->ccid2hctx_arsent >= hctx->ccid2hctx_cwnd) {
hctx->ccid2hctx_arsent = 0;
hctx->ccid2hctx_ackloss = 0;
}
} else {
/* No acks lost up to now... */
/* decrease ack ratio if enough packets were sent */
if (dp->dccps_l_ack_ratio > 1) {
/* XXX don't calculate denominator each time */
int denom = dp->dccps_l_ack_ratio * dp->dccps_l_ack_ratio -
dp->dccps_l_ack_ratio;
denom = hctx->ccid2hctx_cwnd * hctx->ccid2hctx_cwnd / denom;
if (hctx->ccid2hctx_arsent >= denom) {
ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio - 1);
hctx->ccid2hctx_arsent = 0;
}
} else {
/* we can't increase ack ratio further [1] */
hctx->ccid2hctx_arsent = 0; /* or maybe set it to cwnd*/
}
}
#endif
/* setup RTO timer */
if (!timer_pending(&hctx->ccid2hctx_rtotimer))
ccid2_start_rto_timer(sk);
#ifdef CONFIG_IP_DCCP_CCID2_DEBUG
do {
struct ccid2_seq *seqp = hctx->ccid2hctx_seqt;
while (seqp != hctx->ccid2hctx_seqh) {
ccid2_pr_debug("out seq=%llu acked=%d time=%lu\n",
(unsigned long long)seqp->ccid2s_seq,
seqp->ccid2s_acked, seqp->ccid2s_sent);
seqp = seqp->ccid2s_next;
}
} while (0);
ccid2_pr_debug("=========\n");
ccid2_hc_tx_check_sanity(hctx);
#endif
}
/* XXX Lame code duplication!
* returns -1 if none was found.
* else returns the next offset to use in the function call.
*/
static int ccid2_ackvector(struct sock *sk, struct sk_buff *skb, int offset,
unsigned char **vec, unsigned char *veclen)
{
const struct dccp_hdr *dh = dccp_hdr(skb);
unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
unsigned char *opt_ptr;
const unsigned char *opt_end = (unsigned char *)dh +
(dh->dccph_doff * 4);
unsigned char opt, len;
unsigned char *value;
BUG_ON(offset < 0);
options += offset;
opt_ptr = options;
if (opt_ptr >= opt_end)
return -1;
while (opt_ptr != opt_end) {
opt = *opt_ptr++;
len = 0;
value = NULL;
/* Check if this isn't a single byte option */
if (opt > DCCPO_MAX_RESERVED) {
if (opt_ptr == opt_end)
goto out_invalid_option;
len = *opt_ptr++;
if (len < 3)
goto out_invalid_option;
/*
* Remove the type and len fields, leaving
* just the value size
*/
len -= 2;
value = opt_ptr;
opt_ptr += len;
if (opt_ptr > opt_end)
goto out_invalid_option;
}
switch (opt) {
case DCCPO_ACK_VECTOR_0:
case DCCPO_ACK_VECTOR_1:
*vec = value;
*veclen = len;
return offset + (opt_ptr - options);
}
}
return -1;
out_invalid_option:
DCCP_BUG("Invalid option - this should not happen (previous parsing)!");
return -1;
}
static void ccid2_hc_tx_kill_rto_timer(struct sock *sk)
{
struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
sk_stop_timer(sk, &hctx->ccid2hctx_rtotimer);
ccid2_pr_debug("deleted RTO timer\n");
}
static inline void ccid2_new_ack(struct sock *sk,
struct ccid2_seq *seqp,
unsigned int *maxincr)
{
struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
if (hctx->ccid2hctx_cwnd < hctx->ccid2hctx_ssthresh) {
if (*maxincr > 0 && ++hctx->ccid2hctx_packets_acked == 2) {
hctx->ccid2hctx_cwnd += 1;
*maxincr -= 1;
hctx->ccid2hctx_packets_acked = 0;
}
} else if (++hctx->ccid2hctx_packets_acked >= hctx->ccid2hctx_cwnd) {
hctx->ccid2hctx_cwnd += 1;
hctx->ccid2hctx_packets_acked = 0;
}
/* update RTO */
if (hctx->ccid2hctx_srtt == -1 ||
time_after(jiffies, hctx->ccid2hctx_lastrtt + hctx->ccid2hctx_srtt)) {
unsigned long r = (long)jiffies - (long)seqp->ccid2s_sent;
int s;
/* first measurement */
if (hctx->ccid2hctx_srtt == -1) {
ccid2_pr_debug("R: %lu Time=%lu seq=%llu\n",
r, jiffies,
(unsigned long long)seqp->ccid2s_seq);
ccid2_change_srtt(hctx, r);
hctx->ccid2hctx_rttvar = r >> 1;
} else {
/* RTTVAR */
long tmp = hctx->ccid2hctx_srtt - r;
long srtt;
if (tmp < 0)
tmp *= -1;
tmp >>= 2;
hctx->ccid2hctx_rttvar *= 3;
hctx->ccid2hctx_rttvar >>= 2;
hctx->ccid2hctx_rttvar += tmp;
/* SRTT */
srtt = hctx->ccid2hctx_srtt;
srtt *= 7;
srtt >>= 3;
tmp = r >> 3;
srtt += tmp;
ccid2_change_srtt(hctx, srtt);
}
s = hctx->ccid2hctx_rttvar << 2;
/* clock granularity is 1 when based on jiffies */
if (!s)
s = 1;
hctx->ccid2hctx_rto = hctx->ccid2hctx_srtt + s;
/* must be at least a second */
s = hctx->ccid2hctx_rto / HZ;
/* DCCP doesn't require this [but I like it cuz my code sux] */
#if 1
if (s < 1)
hctx->ccid2hctx_rto = HZ;
#endif
/* max 60 seconds */
if (s > 60)
hctx->ccid2hctx_rto = HZ * 60;
hctx->ccid2hctx_lastrtt = jiffies;
ccid2_pr_debug("srtt: %ld rttvar: %ld rto: %ld (HZ=%d) R=%lu\n",
hctx->ccid2hctx_srtt, hctx->ccid2hctx_rttvar,
hctx->ccid2hctx_rto, HZ, r);
}
/* we got a new ack, so re-start RTO timer */
ccid2_hc_tx_kill_rto_timer(sk);
ccid2_start_rto_timer(sk);
}
static void ccid2_hc_tx_dec_pipe(struct sock *sk)
{
struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
if (hctx->ccid2hctx_pipe == 0)
DCCP_BUG("pipe == 0");
else
hctx->ccid2hctx_pipe--;
if (hctx->ccid2hctx_pipe == 0)
ccid2_hc_tx_kill_rto_timer(sk);
}
static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
{
struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
if (time_before(seqp->ccid2s_sent, hctx->ccid2hctx_last_cong)) {
ccid2_pr_debug("Multiple losses in an RTT---treating as one\n");
return;
}
hctx->ccid2hctx_last_cong = jiffies;
hctx->ccid2hctx_cwnd = hctx->ccid2hctx_cwnd / 2 ? : 1U;
hctx->ccid2hctx_ssthresh = max(hctx->ccid2hctx_cwnd, 2U);
/* Avoid spurious timeouts resulting from Ack Ratio > cwnd */
if (dccp_sk(sk)->dccps_l_ack_ratio > hctx->ccid2hctx_cwnd)
ccid2_change_l_ack_ratio(sk, hctx->ccid2hctx_cwnd);
}
static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
{
struct dccp_sock *dp = dccp_sk(sk);
struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
u64 ackno, seqno;
struct ccid2_seq *seqp;
unsigned char *vector;
unsigned char veclen;
int offset = 0;
int done = 0;
unsigned int maxincr = 0;
ccid2_hc_tx_check_sanity(hctx);
/* check reverse path congestion */
seqno = DCCP_SKB_CB(skb)->dccpd_seq;
/* XXX this whole "algorithm" is broken. Need to fix it to keep track
* of the seqnos of the dupacks so that rpseq and rpdupack are correct
* -sorbo.
*/
/* need to bootstrap */
if (hctx->ccid2hctx_rpdupack == -1) {
hctx->ccid2hctx_rpdupack = 0;
hctx->ccid2hctx_rpseq = seqno;
} else {
/* check if packet is consecutive */
if (dccp_delta_seqno(hctx->ccid2hctx_rpseq, seqno) == 1)
hctx->ccid2hctx_rpseq = seqno;
/* it's a later packet */
else if (after48(seqno, hctx->ccid2hctx_rpseq)) {
hctx->ccid2hctx_rpdupack++;
/* check if we got enough dupacks */
if (hctx->ccid2hctx_rpdupack >= NUMDUPACK) {
hctx->ccid2hctx_rpdupack = -1; /* XXX lame */
hctx->ccid2hctx_rpseq = 0;
ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio);
}
}
}
/* check forward path congestion */
/* still didn't send out new data packets */
if (hctx->ccid2hctx_seqh == hctx->ccid2hctx_seqt)
return;
switch (DCCP_SKB_CB(skb)->dccpd_type) {
case DCCP_PKT_ACK:
case DCCP_PKT_DATAACK:
break;
default:
return;
}
ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
if (after48(ackno, hctx->ccid2hctx_high_ack))
hctx->ccid2hctx_high_ack = ackno;
seqp = hctx->ccid2hctx_seqt;
while (before48(seqp->ccid2s_seq, ackno)) {
seqp = seqp->ccid2s_next;
if (seqp == hctx->ccid2hctx_seqh) {
seqp = hctx->ccid2hctx_seqh->ccid2s_prev;
break;
}
}
/*
* In slow-start, cwnd can increase up to a maximum of Ack Ratio/2
* packets per acknowledgement. Rounding up avoids that cwnd is not
* advanced when Ack Ratio is 1 and gives a slight edge otherwise.
*/
if (hctx->ccid2hctx_cwnd < hctx->ccid2hctx_ssthresh)
maxincr = DIV_ROUND_UP(dp->dccps_l_ack_ratio, 2);
/* go through all ack vectors */
while ((offset = ccid2_ackvector(sk, skb, offset,
&vector, &veclen)) != -1) {
/* go through this ack vector */
while (veclen--) {
const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK;
u64 ackno_end_rl = SUB48(ackno, rl);
ccid2_pr_debug("ackvec start:%llu end:%llu\n",
(unsigned long long)ackno,
(unsigned long long)ackno_end_rl);
/* if the seqno we are analyzing is larger than the
* current ackno, then move towards the tail of our
* seqnos.
*/
while (after48(seqp->ccid2s_seq, ackno)) {
if (seqp == hctx->ccid2hctx_seqt) {
done = 1;
break;
}
seqp = seqp->ccid2s_prev;
}
if (done)
break;
/* check all seqnos in the range of the vector
* run length
*/
while (between48(seqp->ccid2s_seq,ackno_end_rl,ackno)) {
const u8 state = *vector &
DCCP_ACKVEC_STATE_MASK;
/* new packet received or marked */
if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED &&
!seqp->ccid2s_acked) {
if (state ==
DCCP_ACKVEC_STATE_ECN_MARKED) {
ccid2_congestion_event(sk,
seqp);
} else
ccid2_new_ack(sk, seqp,
&maxincr);
seqp->ccid2s_acked = 1;
ccid2_pr_debug("Got ack for %llu\n",
(unsigned long long)seqp->ccid2s_seq);
ccid2_hc_tx_dec_pipe(sk);
}
if (seqp == hctx->ccid2hctx_seqt) {
done = 1;
break;
}
seqp = seqp->ccid2s_prev;
}
if (done)
break;
ackno = SUB48(ackno_end_rl, 1);
vector++;
}
if (done)
break;
}
/* The state about what is acked should be correct now
* Check for NUMDUPACK
*/
seqp = hctx->ccid2hctx_seqt;
while (before48(seqp->ccid2s_seq, hctx->ccid2hctx_high_ack)) {
seqp = seqp->ccid2s_next;
if (seqp == hctx->ccid2hctx_seqh) {
seqp = hctx->ccid2hctx_seqh->ccid2s_prev;
break;
}
}
done = 0;
while (1) {
if (seqp->ccid2s_acked) {
done++;
if (done == NUMDUPACK)
break;
}
if (seqp == hctx->ccid2hctx_seqt)
break;
seqp = seqp->ccid2s_prev;
}
/* If there are at least 3 acknowledgements, anything unacknowledged
* below the last sequence number is considered lost
*/
if (done == NUMDUPACK) {
struct ccid2_seq *last_acked = seqp;
/* check for lost packets */
while (1) {
if (!seqp->ccid2s_acked) {
ccid2_pr_debug("Packet lost: %llu\n",
(unsigned long long)seqp->ccid2s_seq);
/* XXX need to traverse from tail -> head in
* order to detect multiple congestion events in
* one ack vector.
*/
ccid2_congestion_event(sk, seqp);
ccid2_hc_tx_dec_pipe(sk);
}
if (seqp == hctx->ccid2hctx_seqt)
break;
seqp = seqp->ccid2s_prev;
}
hctx->ccid2hctx_seqt = last_acked;
}
/* trim acked packets in tail */
while (hctx->ccid2hctx_seqt != hctx->ccid2hctx_seqh) {
if (!hctx->ccid2hctx_seqt->ccid2s_acked)
break;
hctx->ccid2hctx_seqt = hctx->ccid2hctx_seqt->ccid2s_next;
}
ccid2_hc_tx_check_sanity(hctx);
}
static int ccid2_hc_tx_init(struct ccid *ccid, struct sock *sk)
{
struct ccid2_hc_tx_sock *hctx = ccid_priv(ccid);
struct dccp_sock *dp = dccp_sk(sk);
u32 max_ratio;
/* RFC 4341, 5: initialise ssthresh to arbitrarily high (max) value */
hctx->ccid2hctx_ssthresh = ~0U;
/*
* RFC 4341, 5: "The cwnd parameter is initialized to at most four
* packets for new connections, following the rules from [RFC3390]".
* We need to convert the bytes of RFC3390 into the packets of RFC 4341.
*/
hctx->ccid2hctx_cwnd = clamp(4380U / dp->dccps_mss_cache, 2U, 4U);
/* Make sure that Ack Ratio is enabled and within bounds. */
max_ratio = DIV_ROUND_UP(hctx->ccid2hctx_cwnd, 2);
if (dp->dccps_l_ack_ratio == 0 || dp->dccps_l_ack_ratio > max_ratio)
dp->dccps_l_ack_ratio = max_ratio;
/* XXX init ~ to window size... */
if (ccid2_hc_tx_alloc_seq(hctx))
return -ENOMEM;
hctx->ccid2hctx_rto = 3 * HZ;
ccid2_change_srtt(hctx, -1);
hctx->ccid2hctx_rttvar = -1;
hctx->ccid2hctx_rpdupack = -1;
hctx->ccid2hctx_last_cong = jiffies;
setup_timer(&hctx->ccid2hctx_rtotimer, ccid2_hc_tx_rto_expire,
(unsigned long)sk);
ccid2_hc_tx_check_sanity(hctx);
return 0;
}
static void ccid2_hc_tx_exit(struct sock *sk)
{
struct ccid2_hc_tx_sock *hctx = ccid2_hc_tx_sk(sk);
int i;
ccid2_hc_tx_kill_rto_timer(sk);
for (i = 0; i < hctx->ccid2hctx_seqbufc; i++)
kfree(hctx->ccid2hctx_seqbuf[i]);
hctx->ccid2hctx_seqbufc = 0;
}
static void ccid2_hc_rx_packet_recv(struct sock *sk, struct sk_buff *skb)
{
const struct dccp_sock *dp = dccp_sk(sk);
struct ccid2_hc_rx_sock *hcrx = ccid2_hc_rx_sk(sk);
switch (DCCP_SKB_CB(skb)->dccpd_type) {
case DCCP_PKT_DATA:
case DCCP_PKT_DATAACK:
hcrx->ccid2hcrx_data++;
if (hcrx->ccid2hcrx_data >= dp->dccps_r_ack_ratio) {
dccp_send_ack(sk);
hcrx->ccid2hcrx_data = 0;
}
break;
}
}
static struct ccid_operations ccid2 = {
.ccid_id = DCCPC_CCID2,
.ccid_name = "TCP-like",
.ccid_owner = THIS_MODULE,
.ccid_hc_tx_obj_size = sizeof(struct ccid2_hc_tx_sock),
.ccid_hc_tx_init = ccid2_hc_tx_init,
.ccid_hc_tx_exit = ccid2_hc_tx_exit,
.ccid_hc_tx_send_packet = ccid2_hc_tx_send_packet,
.ccid_hc_tx_packet_sent = ccid2_hc_tx_packet_sent,
.ccid_hc_tx_packet_recv = ccid2_hc_tx_packet_recv,
.ccid_hc_rx_obj_size = sizeof(struct ccid2_hc_rx_sock),
.ccid_hc_rx_packet_recv = ccid2_hc_rx_packet_recv,
};
#ifdef CONFIG_IP_DCCP_CCID2_DEBUG
module_param(ccid2_debug, bool, 0644);
MODULE_PARM_DESC(ccid2_debug, "Enable debug messages");
#endif
static __init int ccid2_module_init(void)
{
return ccid_register(&ccid2);
}
module_init(ccid2_module_init);
static __exit void ccid2_module_exit(void)
{
ccid_unregister(&ccid2);
}
module_exit(ccid2_module_exit);
MODULE_AUTHOR("Andrea Bittau <a.bittau@cs.ucl.ac.uk>");
MODULE_DESCRIPTION("DCCP TCP-Like (CCID2) CCID");
MODULE_LICENSE("GPL");
MODULE_ALIAS("net-dccp-ccid-2");
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