net-next-2.6 [PATCH 0/7] dccp: add support for dynamic parameter updates

@@ -474,6 +474,7 @@ static inline int dccp_ack_pending(const struct sock *sk)
 	return dccp_ackvec_pending(sk) || inet_csk_ack_scheduled(sk);
 }
 
+extern int  dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val);
 extern int  dccp_feat_finalise_settings(struct dccp_sock *dp);
 extern int  dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq);
 extern int  dccp_feat_insert_opts(struct dccp_sock*, struct dccp_request_sock*,

@@ -129,6 +129,7 @@ extern int  dccp_feat_clone_list(struct list_head const *, struct list_head *);
 
 extern void dccp_encode_value_var(const u64 value, u8 *to, const u8 len);
 extern u64  dccp_decode_value_var(const u8 *bf, const u8 len);
+extern u64  dccp_feat_nn_get(struct sock *sk, u8 feat);
 
 extern int  dccp_insert_option_mandatory(struct sk_buff *skb);
 extern int  dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,

77 lines not on this page · raw message

@@ -344,6 +344,20 @@ static int __dccp_feat_activate(struct sock *sk, const int idx,
 	return dccp_feat_table[idx].activation_hdlr(sk, val, rx);
 }
 
+/**
+ * dccp_feat_activate  -  Activate feature value on socket
+ * @sk: fully connected DCCP socket (after handshake is complete)
+ * @feat_num: feature to activate, one of %dccp_feature_numbers
+ * @local: whether local (1) or remote (0) @feat_num is meant
+ * @fval: the value (SP or NN) to activate, or NULL to use the default value
+ * For general use this function is preferable over __dccp_feat_activate().
+ */
+static int dccp_feat_activate(struct sock *sk, u8 feat_num, bool local,
+			      dccp_feat_val const *fval)
+{
+	return __dccp_feat_activate(sk, dccp_feat_index(feat_num), local, fval);
+}
+
 /* Test for "Req'd" feature (RFC 4340, 6.4) */
 static inline int dccp_feat_must_be_understood(u8 feat_num)
 {

@@ -1252,6 +1266,100 @@ confirmation_failed:
 }
 
 /**
+ * dccp_feat_handle_nn_established  -  Fast-path reception of NN options
+ * @sk:		socket of an established DCCP connection
+ * @mandatory:	whether @opt was preceded by a Mandatory option
+ * @opt:	%DCCPO_CHANGE_L | %DCCPO_CONFIRM_R (NN only)
+ * @feat:	NN number, one of %dccp_feature_numbers
+ * @val:	NN value
+ * @len:	length of @val in bytes
+ * This function combines the functionality of change_recv/confirm_recv, with
+ * the following differences (reset codes are the same):
+ *    - cleanup after receiving the Confirm;
+ *    - values are directly activated after successful parsing;
+ *    - deliberately restricted to NN features.
+ * The restriction to NN features is essential since SP features can have non-
+ * predictable outcomes (depending on the remote configuration), and are inter-
+ * dependent (CCIDs for instance cause further dependencies).
+ */
+static u8 dccp_feat_handle_nn_established(struct sock *sk, u8 mandatory, u8 opt,
+					  u8 feat, u8 *val, u8 len)
+{
+	struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
+	const bool local = (opt = DCCPO_CONFIRM_R);
+	struct dccp_feat_entry *entry;
+	u8 type = dccp_feat_type(feat);
+	dccp_feat_val fval;
+
+	dccp_feat_print_opt(opt, feat, val, len, mandatory);
+
+	/* Ignore non-mandatory unknown and non-NN features */
+	if (type = FEAT_UNKNOWN) {
+		if (local && !mandatory)
+			return 0;
+		goto fast_path_unknown;
+	} else if (type != FEAT_NN) {
+		return 0;
+	}
+
+	/*
+	 * We don't accept empty Confirms, since in fast-path feature
+	 * negotiation the values are enabled immediately after sending
+	 * the Change option.
+	 * Empty Changes on the other hand are invalid (RFC 4340, 6.1).
+	 */
+	if (len = 0 || len > sizeof(fval.nn))
+		goto fast_path_unknown;
+
+	if (opt = DCCPO_CHANGE_L) {
+		fval.nn = dccp_decode_value_var(val, len);
+		if (!dccp_feat_is_valid_nn_val(feat, fval.nn))
+			goto fast_path_unknown;
+
+		if (dccp_feat_push_confirm(fn, feat, local, &fval) ||
+		    dccp_feat_activate(sk, feat, local, &fval))
+			return DCCP_RESET_CODE_TOO_BUSY;
+
+		/* set the `Ack Pending' flag to piggyback a Confirm */
+		inet_csk_schedule_ack(sk);
+
+	} else if (opt = DCCPO_CONFIRM_R) {
+		entry = dccp_feat_list_lookup(fn, feat, local);
+		if (entry = NULL || entry->state != FEAT_CHANGING)
+			return 0;
+
+		fval.nn = dccp_decode_value_var(val, len);
+		/*
+		 * Just ignore a value that doesn't match our current value.
+		 * If the option changes twice within two RTTs, then at least
+		 * one CONFIRM will be received for the old value after a
+		 * new CHANGE was sent.
+		 */
+		if (fval.nn != entry->val.nn)
+			return 0;
+
+		/* Only activate after receiving the Confirm option (6.6.1). */
+		dccp_feat_activate(sk, feat, local, &fval);
+
+		/* It has been confirmed - so remove the entry */
+		dccp_feat_list_pop(entry);
+
+	} else {
+		DCCP_WARN("Received illegal option %u\n", opt);
+		goto fast_path_failed;
+	}
+	return 0;
+
+fast_path_unknown:
+	if (!mandatory)
+		return dccp_push_empty_confirm(fn, feat, local);
+
+fast_path_failed:
+	return mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
+			 : DCCP_RESET_CODE_OPTION_ERROR;
+}
+
+/**
  * dccp_feat_parse_options  -  Process Feature-Negotiation Options
  * @sk: for general use and used by the client during connection setup
  * @dreq: used by the server during connection setup

@@ -1286,6 +1394,14 @@ int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
 			return dccp_feat_confirm_recv(fn, mandatory, opt, feat,
 						      val, len, server);
 		}
+		break;
+	/*
+	 *	Support for exchanging NN options on an established connection.
+	 */
+	case DCCP_OPEN:
+	case DCCP_PARTOPEN:
+		return dccp_feat_handle_nn_established(sk, mandatory, opt, feat,
+						       val, len);
 	}
 	return 0;	/* ignore FN options in all other states */
 }

@@ -665,11 +665,22 @@ int dccp_feat_insert_opts(struct dccp_sock *dp, struct dccp_request_sock *dreq,
 			return -1;
 		if (pos->needs_mandatory && dccp_insert_option_mandatory(skb))
 			return -1;
-		/*
-		 * Enter CHANGING after transmitting the Change option (6.6.2).
-		 */
-		if (pos->state = FEAT_INITIALISING)
-			pos->state = FEAT_CHANGING;
+
+		if (skb->sk->sk_state = DCCP_OPEN &&
+		    (opt = DCCPO_CONFIRM_R || opt = DCCPO_CONFIRM_L)) {
+			/*
+			 * Confirms don't get retransmitted (6.6.3) once the
+			 * connection is in state OPEN
+			 */
+			dccp_feat_list_pop(pos);
+		} else {
+			/*
+			 * Enter CHANGING after transmitting the Change
+			 * option (6.6.2).
+			 */
+			if (pos->state = FEAT_INITIALISING)
+				pos->state = FEAT_CHANGING;
+		}
 	}
 	return 0;
 }

@@ -184,7 +184,6 @@ int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized)
 	dp->dccps_rate_last	= jiffies;
 	dp->dccps_role		= DCCP_ROLE_UNDEFINED;
 	dp->dccps_service	= DCCP_SERVICE_CODE_IS_ABSENT;
-	dp->dccps_l_ack_ratio	= dp->dccps_r_ack_ratio = 1;
 	dp->dccps_tx_qlen	= sysctl_dccp_tx_qlen;
 
 	dccp_init_xmit_timers(sk);

@@ -494,8 +494,16 @@ static void ccid2_hc_tx_packet_recv(struct sock *sk, struct sk_buff *skb)
 			if (hc->tx_rpdupack >= NUMDUPACK) {
 				hc->tx_rpdupack = -1; /* XXX lame */
 				hc->tx_rpseq    = 0;
-
+#ifdef __CCID2_COPES_GRACEFULLY_WITH_ACK_CONGESTION_CONTROL__
+				/*
+				 * FIXME: Ack Congestion Control is broken; in
+				 * the current state instabilities occurred with
+				 * Ack Ratios greater than 1; causing hang-ups
+				 * and long RTO timeouts. This needs to be fixed
+				 * before opening up dynamic changes. -- gerrit
+				 */
 				ccid2_change_l_ack_ratio(sk, 2 * dp->dccps_l_ack_ratio);
+#endif
 			}
 		}
 	}

@@ -43,6 +43,12 @@ struct ccid2_seq {
 #define CCID2_SEQBUF_LEN 1024
 #define CCID2_SEQBUF_MAX 128
 
+/*
+ * Multiple of congestion window to keep the sequence window at
+ * (RFC 4340 7.5.2)
+ */
+#define CCID2_WIN_CHANGE_FACTOR 5
+
 /**
  * struct ccid2_hc_tx_sock - CCID2 TX half connection
  * @tx_{cwnd,ssthresh,pipe}: as per RFC 4341, section 5

73 lines not on this page · raw message

@@ -411,7 +411,7 @@ static void ccid2_new_ack(struct sock *sk, struct ccid2_seq *seqp,
 	if (hc->tx_cwnd < dp->dccps_l_seq_win &&
 	    r_seq_used < dp->dccps_r_seq_win) {
 		if (hc->tx_cwnd < hc->tx_ssthresh) {
-			if (*maxincr > 0 && ++hc->tx_packets_acked = 2) {
+			if (*maxincr > 0 && ++hc->tx_packets_acked >= 2) {
 				hc->tx_cwnd += 1;
 				*maxincr    -= 1;
 				hc->tx_packets_acked = 0;

@@ -101,6 +101,24 @@ static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val)
 				   min_t(u32, val, DCCPF_ACK_RATIO_MAX));
 }
 
+static void ccid2_check_l_ack_ratio(struct sock *sk)
+{
+	struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
+
+	/*
+	 * After a loss, idle period, application limited period, or RTO we
+	 * need to check that the ack ratio is still less than the congestion
+	 * window. Otherwise, we will send an entire congestion window of
+	 * packets and got no response because we haven't sent ack ratio
+	 * packets yet.
+	 * If the ack ratio does need to be reduced, we reduce it to half of
+	 * the congestion window (or 1 if that's zero) instead of to the
+	 * congestion window. This prevents problems if one ack is lost.
+	 */
+	if (dccp_feat_nn_get(sk, DCCPF_ACK_RATIO) > hc->tx_cwnd)
+		ccid2_change_l_ack_ratio(sk, hc->tx_cwnd/2 ? : 1U);
+}
+
 static void ccid2_change_l_seq_window(struct sock *sk, u64 val)
 {
 	dccp_feat_signal_nn_change(sk, DCCPF_SEQUENCE_WINDOW,

@@ -187,6 +205,8 @@ static void ccid2_cwnd_application_limited(struct sock *sk, const u32 now)
 	}
 	hc->tx_cwnd_used  = 0;
 	hc->tx_cwnd_stamp = now;
+
+	ccid2_check_l_ack_ratio(sk);
 }
 
 /* This borrows the code of tcp_cwnd_restart() */

@@ -205,6 +225,8 @@ static void ccid2_cwnd_restart(struct sock *sk, const u32 now)
 
 	hc->tx_cwnd_stamp = now;
 	hc->tx_cwnd_used  = 0;
+
+	ccid2_check_l_ack_ratio(sk);
 }
 
 static void ccid2_hc_tx_packet_sent(struct sock *sk, unsigned int len)

@@ -461,9 +483,7 @@ static void ccid2_congestion_event(struct sock *sk, struct ccid2_seq *seqp)
 	hc->tx_cwnd      = hc->tx_cwnd / 2 ? : 1U;
 	hc->tx_ssthresh  = max(hc->tx_cwnd, 2U);
 
-	/* Avoid spurious timeouts resulting from Ack Ratio > cwnd */
-	if (dccp_sk(sk)->dccps_l_ack_ratio > hc->tx_cwnd)
-		ccid2_change_l_ack_ratio(sk, hc->tx_cwnd);
+	ccid2_check_l_ack_ratio(sk);
 }
 
 static int ccid2_hc_tx_parse_options(struct sock *sk, u8 packet_type,