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dccp ccid-3: Simplified handling of TX states

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Since CCIDs are only used during the established phase of a connection,
they have very little internal state; this specifically reduces to:

 * "no packet sent" if and only if s == 0, for the TX packet size s;

 * when the first packet has been sent (i.e. `s' > 0), the question is whether
   or not feedback has been received:
   - if a feedback packet is received, "feedback = yes" is set,
   - if the nofeedback timer expires,  "feedback = no"  is set.

Thus the CCID only needs to remember state about whether or not feedback
has been received. This is now implemented using a boolean flag, which is
toggled when a feedback packet arrives or the nofeedback timer expires.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
This commit is contained in:
Gerrit Renker 2008-09-04 07:30:19 +02:00
parent f76fd327a8
commit d0c05fe444
2 changed files with 8 additions and 44 deletions
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41
net/dccp/ccids/ccid3.c
View file

@ -49,31 +49,6 @@ static int ccid3_debug;
/*
* Transmitter Half-Connection Routines
*/
#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
static const char *ccid3_tx_state_name(enum ccid3_hc_tx_states state)
{
static char *ccid3_state_names[] = {
[TFRC_SSTATE_NO_SENT] = "NO_SENT",
[TFRC_SSTATE_NO_FBACK] = "NO_FBACK",
[TFRC_SSTATE_FBACK] = "FBACK",
};
return ccid3_state_names[state];
}
#endif
static void ccid3_hc_tx_set_state(struct sock *sk,
enum ccid3_hc_tx_states state)
{
struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
enum ccid3_hc_tx_states oldstate = hctx->state;
ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
dccp_role(sk), sk, ccid3_tx_state_name(oldstate),
ccid3_tx_state_name(state));
WARN_ON(state == oldstate);
hctx->state = state;
}
/*
* Compute the initial sending rate X_init in the manner of RFC 3390:
@ -206,16 +181,15 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
goto restart_timer;
}
ccid3_pr_debug("%s(%p, state=%s) - entry \n", dccp_role(sk), sk,
ccid3_tx_state_name(hctx->state));
ccid3_pr_debug("%s(%p) entry with%s feedback\n", dccp_role(sk), sk,
hctx->feedback ? "" : "out");
/* Ignore and do not restart after leaving the established state */
if ((1 << sk->sk_state) & ~(DCCPF_OPEN | DCCPF_PARTOPEN))
goto out;
/* Reset feedback state to "no feedback received" */
if (hctx->state == TFRC_SSTATE_FBACK)
ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
hctx->feedback = false;
/*
* Determine new allowed sending rate X as per draft rfc3448bis-00, 4.4
@ -290,7 +264,7 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
if (unlikely(skb->len == 0))
return -EBADMSG;
if (hctx->state == TFRC_SSTATE_NO_SENT) {
if (hctx->s == 0) {
sk_reset_timer(sk, &hctx->no_feedback_timer, (jiffies +
usecs_to_jiffies(TFRC_INITIAL_TIMEOUT)));
hctx->last_win_count = 0;
@ -324,8 +298,6 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
}
ccid3_update_send_interval(hctx);
ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
} else {
delay = ktime_us_delta(hctx->t_nom, now);
ccid3_pr_debug("delay=%ld\n", (long)delay);
@ -396,8 +368,8 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
/*
* Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3
*/
if (hctx->state == TFRC_SSTATE_NO_FBACK) {
ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
if (!hctx->feedback) {
hctx->feedback = true;
if (hctx->t_rto == 0) {
/*
@ -502,7 +474,6 @@ static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk)
{
struct ccid3_hc_tx_sock *hctx = ccid_priv(ccid);
hctx->state = TFRC_SSTATE_NO_SENT;
hctx->hist = NULL;
setup_timer(&hctx->no_feedback_timer,
ccid3_hc_tx_no_feedback_timer, (unsigned long)sk);

11
net/dccp/ccids/ccid3.h
View file

@ -70,13 +70,6 @@ enum ccid3_options {
TFRC_OPT_RECEIVE_RATE = 194,
};
/* TFRC sender states */
enum ccid3_hc_tx_states {
TFRC_SSTATE_NO_SENT = 1,
TFRC_SSTATE_NO_FBACK,
TFRC_SSTATE_FBACK,
};
/** struct ccid3_hc_tx_sock - CCID3 sender half-connection socket
*
* @x - Current sending rate in 64 * bytes per second
@ -87,7 +80,7 @@ enum ccid3_hc_tx_states {
* @s - Packet size in bytes
* @t_rto - Nofeedback Timer setting in usecs
* @t_ipi - Interpacket (send) interval (RFC 3448, 4.6) in usecs
* @state - Sender state, one of %ccid3_hc_tx_states
* @feedback - Whether feedback has been received or not
* @last_win_count - Last window counter sent
* @t_last_win_count - Timestamp of earliest packet with
* last_win_count value sent
@ -105,7 +98,7 @@ struct ccid3_hc_tx_sock {
u32 t_rto;
u32 t_ipi;
u16 s;
enum ccid3_hc_tx_states state:8;
bool feedback:1;
u8 last_win_count;
ktime_t t_last_win_count;
struct timer_list no_feedback_timer;