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Date: Mon, 28 Jul 2008 19:13:58 +0100
From: Gerrit Renker <gerrit@....abdn.ac.uk>
To: dccp@...r.kernel.org
Cc: netdev@...r.kernel.org, Gerrit Renker <gerrit@....abdn.ac.uk>
Subject: [PATCH 2/7] dccp ccid-3: Simplified handling of TX states
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@....abdn.ac.uk>
---
net/dccp/ccids/ccid3.c | 41 ++++++-----------------------------------
net/dccp/ccids/ccid3.h | 11 ++---------
2 files changed, 8 insertions(+), 44 deletions(-)
--- a/net/dccp/ccids/ccid3.h
+++ b/net/dccp/ccids/ccid3.h
@@ -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;
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -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);
--
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