Merge branch 'dccp' of git://eden-feed.erg.abdn.ac.uk/net-next-2.6

net/dccp/ccids/ccid2.c

@@ -85,7 +85,6 @@ static int ccid2_hc_tx_send_packet(struct sock *sk, struct sk_buff *skb)
 
 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)->tx_cwnd, 2);
 
 	/*
@@ -98,14 +97,33 @@ static void ccid2_change_l_ack_ratio(struct sock *sk, u32 val)
 		DCCP_WARN("Limiting Ack Ratio (%u) to %u\n", val, max_ratio);
 		val = max_ratio;
 	}
-	if (val > DCCPF_ACK_RATIO_MAX)
-		val = DCCPF_ACK_RATIO_MAX;
+	dccp_feat_signal_nn_change(sk, DCCPF_ACK_RATIO,
+				   min_t(u32, val, DCCPF_ACK_RATIO_MAX));
+}
 
-	if (val == dp->dccps_l_ack_ratio)
-		return;
+static void ccid2_check_l_ack_ratio(struct sock *sk)
+{
+	struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
 
-	ccid2_pr_debug("changing local ack ratio to %u\n", val);
-	dp->dccps_l_ack_ratio = val;
+	/*
+	 * 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,
+				   clamp_val(val, DCCPF_SEQ_WMIN,
+						  DCCPF_SEQ_WMAX));
 }
 
 static void ccid2_hc_tx_rto_expire(unsigned long data)
@@ -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)
@@ -405,17 +427,37 @@ static void ccid2_new_ack(struct sock *sk, struct ccid2_seq *seqp,
 			  unsigned int *maxincr)
 {
 	struct ccid2_hc_tx_sock *hc = ccid2_hc_tx_sk(sk);
-
-	if (hc->tx_cwnd < hc->tx_ssthresh) {
-		if (*maxincr > 0 && ++hc->tx_packets_acked == 2) {
+	struct dccp_sock *dp = dccp_sk(sk);
+	int r_seq_used = hc->tx_cwnd / dp->dccps_l_ack_ratio;
+
+	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) {
+				hc->tx_cwnd += 1;
+				*maxincr    -= 1;
+				hc->tx_packets_acked = 0;
+			}
+		} else if (++hc->tx_packets_acked >= hc->tx_cwnd) {
 			hc->tx_cwnd += 1;
-			*maxincr    -= 1;
 			hc->tx_packets_acked = 0;
 		}
-	} else if (++hc->tx_packets_acked >= hc->tx_cwnd) {
-			hc->tx_cwnd += 1;
-			hc->tx_packets_acked = 0;
 	}
+
+	/*
+	 * Adjust the local sequence window and the ack ratio to allow about
+	 * 5 times the number of packets in the network (RFC 4340 7.5.2)
+	 */
+	if (r_seq_used * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_r_seq_win)
+		ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio * 2);
+	else if (r_seq_used * CCID2_WIN_CHANGE_FACTOR < dp->dccps_r_seq_win/2)
+		ccid2_change_l_ack_ratio(sk, dp->dccps_l_ack_ratio / 2 ? : 1U);
+
+	if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR >= dp->dccps_l_seq_win)
+		ccid2_change_l_seq_window(sk, dp->dccps_l_seq_win * 2);
+	else if (hc->tx_cwnd * CCID2_WIN_CHANGE_FACTOR < dp->dccps_l_seq_win/2)
+		ccid2_change_l_seq_window(sk, dp->dccps_l_seq_win / 2);
+
 	/*
 	 * FIXME: RTT is sampled several times per acknowledgment (for each
 	 * entry in the Ack Vector), instead of once per Ack (as in TCP SACK).
@@ -441,9 +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,
@@ -494,8 +534,16 @@ 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
 			}
 		}
 	}

net/dccp/ccids/ccid2.h

@@ -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

net/dccp/dccp.h

@@ -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*,

net/dccp/feat.c

@@ -12,6 +12,7 @@
  *  -----------
  *  o Feature negotiation is coordinated with connection setup (as in TCP), wild
  *    changes of parameters of an established connection are not supported.
+ *  o Changing non-negotiable (NN) values is supported in state OPEN/PARTOPEN.
  *  o All currently known SP features have 1-byte quantities. If in the future
  *    extensions of RFCs 4340..42 define features with item lengths larger than
  *    one byte, a feature-specific extension of the code will be required.
@@ -343,6 +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)
 {
@@ -650,11 +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;
 }
@@ -730,6 +756,70 @@ int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
 				  0, list, len);
 }
 
+/**
+ * dccp_feat_nn_get  -  Query current/pending value of NN feature
+ * @sk: DCCP socket of an established connection
+ * @feat: NN feature number from %dccp_feature_numbers
+ * For a known NN feature, returns value currently being negotiated, or
+ * current (confirmed) value if no negotiation is going on.
+ */
+u64 dccp_feat_nn_get(struct sock *sk, u8 feat)
+{
+	if (dccp_feat_type(feat) == FEAT_NN) {
+		struct dccp_sock *dp = dccp_sk(sk);
+		struct dccp_feat_entry *entry;
+
+		entry = dccp_feat_list_lookup(&dp->dccps_featneg, feat, 1);
+		if (entry != NULL)
+			return entry->val.nn;
+
+		switch (feat) {
+		case DCCPF_ACK_RATIO:
+			return dp->dccps_l_ack_ratio;
+		case DCCPF_SEQUENCE_WINDOW:
+			return dp->dccps_l_seq_win;
+		}
+	}
+	DCCP_BUG("attempt to look up unsupported feature %u", feat);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(dccp_feat_nn_get);
+
+/**
+ * dccp_feat_signal_nn_change  -  Update NN values for an established connection
+ * @sk: DCCP socket of an established connection
+ * @feat: NN feature number from %dccp_feature_numbers
+ * @nn_val: the new value to use
+ * This function is used to communicate NN updates out-of-band.
+ */
+int dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val)
+{
+	struct list_head *fn = &dccp_sk(sk)->dccps_featneg;
+	dccp_feat_val fval = { .nn = nn_val };
+	struct dccp_feat_entry *entry;
+
+	if (sk->sk_state != DCCP_OPEN && sk->sk_state != DCCP_PARTOPEN)
+		return 0;
+
+	if (dccp_feat_type(feat) != FEAT_NN ||
+	    !dccp_feat_is_valid_nn_val(feat, nn_val))
+		return -EINVAL;
+
+	if (nn_val == dccp_feat_nn_get(sk, feat))
+		return 0;	/* already set or negotiation under way */
+
+	entry = dccp_feat_list_lookup(fn, feat, 1);
+	if (entry != NULL) {
+		dccp_pr_debug("Clobbering existing NN entry %llu -> %llu\n",
+			      (unsigned long long)entry->val.nn,
+			      (unsigned long long)nn_val);
+		dccp_feat_list_pop(entry);
+	}
+
+	inet_csk_schedule_ack(sk);
+	return dccp_feat_push_change(fn, feat, 1, 0, &fval);
+}
+EXPORT_SYMBOL_GPL(dccp_feat_signal_nn_change);
 
 /*
  *	Tracking features whose value depend on the choice of CCID
@@ -1186,6 +1276,100 @@ static u8 dccp_feat_confirm_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
 			    : DCCP_RESET_CODE_OPTION_ERROR;
 }
 
+/**
+ * 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
@@ -1221,6 +1405,14 @@ 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 */
 }

net/dccp/feat.h

@@ -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,

net/dccp/proto.c

@@ -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);