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@erg.abdn.ac.uk>
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@ -49,31 +49,6 @@ static int ccid3_debug;
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/*
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* Transmitter Half-Connection Routines
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*/
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#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
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static const char *ccid3_tx_state_name(enum ccid3_hc_tx_states state)
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{
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static char *ccid3_state_names[] = {
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[TFRC_SSTATE_NO_SENT] = "NO_SENT",
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[TFRC_SSTATE_NO_FBACK] = "NO_FBACK",
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[TFRC_SSTATE_FBACK] = "FBACK",
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};
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return ccid3_state_names[state];
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}
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#endif
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static void ccid3_hc_tx_set_state(struct sock *sk,
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enum ccid3_hc_tx_states state)
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{
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struct ccid3_hc_tx_sock *hctx = ccid3_hc_tx_sk(sk);
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enum ccid3_hc_tx_states oldstate = hctx->state;
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ccid3_pr_debug("%s(%p) %-8.8s -> %s\n",
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dccp_role(sk), sk, ccid3_tx_state_name(oldstate),
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ccid3_tx_state_name(state));
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WARN_ON(state == oldstate);
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hctx->state = state;
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}
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/*
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* Compute the initial sending rate X_init in the manner of RFC 3390:
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@ -206,16 +181,15 @@ static void ccid3_hc_tx_no_feedback_timer(unsigned long data)
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goto restart_timer;
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}
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ccid3_pr_debug("%s(%p, state=%s) - entry \n", dccp_role(sk), sk,
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ccid3_tx_state_name(hctx->state));
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ccid3_pr_debug("%s(%p) entry with%s feedback\n", dccp_role(sk), sk,
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hctx->feedback ? "" : "out");
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/* Ignore and do not restart after leaving the established state */
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if ((1 << sk->sk_state) & ~(DCCPF_OPEN | DCCPF_PARTOPEN))
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goto out;
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/* Reset feedback state to "no feedback received" */
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if (hctx->state == TFRC_SSTATE_FBACK)
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ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
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hctx->feedback = false;
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/*
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* Determine new allowed sending rate X as per draft rfc3448bis-00, 4.4
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@ -290,7 +264,7 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
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if (unlikely(skb->len == 0))
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return -EBADMSG;
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if (hctx->state == TFRC_SSTATE_NO_SENT) {
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if (hctx->s == 0) {
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sk_reset_timer(sk, &hctx->no_feedback_timer, (jiffies +
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usecs_to_jiffies(TFRC_INITIAL_TIMEOUT)));
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hctx->last_win_count = 0;
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@ -324,8 +298,6 @@ static int ccid3_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
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}
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ccid3_update_send_interval(hctx);
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ccid3_hc_tx_set_state(sk, TFRC_SSTATE_NO_FBACK);
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} else {
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delay = ktime_us_delta(hctx->t_nom, now);
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ccid3_pr_debug("delay=%ld\n", (long)delay);
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@ -396,8 +368,8 @@ static void ccid3_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
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/*
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* Update allowed sending rate X as per draft rfc3448bis-00, 4.2/3
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*/
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if (hctx->state == TFRC_SSTATE_NO_FBACK) {
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ccid3_hc_tx_set_state(sk, TFRC_SSTATE_FBACK);
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if (!hctx->feedback) {
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hctx->feedback = true;
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if (hctx->t_rto == 0) {
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/*
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@ -502,7 +474,6 @@ static int ccid3_hc_tx_init(struct ccid *ccid, struct sock *sk)
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{
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struct ccid3_hc_tx_sock *hctx = ccid_priv(ccid);
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hctx->state = TFRC_SSTATE_NO_SENT;
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hctx->hist = NULL;
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setup_timer(&hctx->no_feedback_timer,
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ccid3_hc_tx_no_feedback_timer, (unsigned long)sk);
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@ -70,13 +70,6 @@ enum ccid3_options {
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TFRC_OPT_RECEIVE_RATE = 194,
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};
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/* TFRC sender states */
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enum ccid3_hc_tx_states {
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TFRC_SSTATE_NO_SENT = 1,
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TFRC_SSTATE_NO_FBACK,
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TFRC_SSTATE_FBACK,
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};
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/** struct ccid3_hc_tx_sock - CCID3 sender half-connection socket
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*
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* @x - Current sending rate in 64 * bytes per second
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@ -87,7 +80,7 @@ enum ccid3_hc_tx_states {
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* @s - Packet size in bytes
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* @t_rto - Nofeedback Timer setting in usecs
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* @t_ipi - Interpacket (send) interval (RFC 3448, 4.6) in usecs
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* @state - Sender state, one of %ccid3_hc_tx_states
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* @feedback - Whether feedback has been received or not
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* @last_win_count - Last window counter sent
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* @t_last_win_count - Timestamp of earliest packet with
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* last_win_count value sent
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@ -105,7 +98,7 @@ struct ccid3_hc_tx_sock {
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u32 t_rto;
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u32 t_ipi;
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u16 s;
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enum ccid3_hc_tx_states state:8;
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bool feedback:1;
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u8 last_win_count;
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ktime_t t_last_win_count;
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struct timer_list no_feedback_timer;
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