From 71bb49596bbf4e5a3328e1704d18604e822ba181 Mon Sep 17 00:00:00 2001
From: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Date: Thu, 4 Sep 2008 07:30:19 +0200
Subject: dccp: Query supported CCIDs

This provides a data structure to record which CCIDs are locally supported
and three accessor functions:
 - a test function for internal use which is used to validate CCID requests
   made by the user;
 - a copy function so that the list can be used for feature-negotiation;
 - documented getsockopt() support so that the user can query capabilities.

The data structure is a table which is filled in at compile-time with the
list of available CCIDs (which in turn depends on the Kconfig choices).

Using the copy function for cloning the list of supported CCIDs is useful for
feature negotiation, since the negotiation is now with the full list of available
CCIDs (e.g. {2, 3}) instead of the default value {2}. This means negotiation
will not fail if the peer requests to use CCID3 instead of CCID2.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
---
 Documentation/networking/dccp.txt | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'Documentation')

diff --git a/Documentation/networking/dccp.txt b/Documentation/networking/dccp.txt
index 39131a3c78f8..f0aeb20fa63b 100644
--- a/Documentation/networking/dccp.txt
+++ b/Documentation/networking/dccp.txt
@@ -57,6 +57,10 @@ can be set before calling bind().
 DCCP_SOCKOPT_GET_CUR_MPS is read-only and retrieves the current maximum packet
 size (application payload size) in bytes, see RFC 4340, section 14.
 
+DCCP_SOCKOPT_AVAILABLE_CCIDS is also read-only and returns the list of CCIDs
+supported by the endpoint (see include/linux/dccp.h for symbolic constants).
+The caller needs to provide a sufficiently large (> 2) array of type uint8_t.
+
 DCCP_SOCKOPT_SERVER_TIMEWAIT enables the server (listening socket) to hold
 timewait state when closing the connection (RFC 4340, 8.3). The usual case is
 that the closing server sends a CloseReq, whereupon the client holds timewait
-- 
cgit v1.2.3


From 17c30b40ed79e9f3955e884632c8f01e577b204a Mon Sep 17 00:00:00 2001
From: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Date: Thu, 4 Sep 2008 07:30:19 +0200
Subject: dccp: Deprecate Ack Ratio sysctl

This patch deprecates the Ack Ratio sysctl, since
 * Ack Ratio is entirely ignored by CCID-3 and CCID-4,
 * Ack Ratio currently doesn't work in CCID-2 (i.e. is always set to 1);
 * even if it would work in CCID-2, there is no point for a user to change it:
   - Ack Ratio is constrained by cwnd (RFC 4341, 6.1.2),
   - if Ack Ratio > cwnd, the system resorts to spurious RTO timeouts
     (since waiting for Acks which will never arrive in this window),
   - cwnd is not a user-configurable value.

The only reasonable place for Ack Ratio is to print it for debugging. It is
planned to do this later on, as part of e.g. dccp_probe.

With this patch Ack Ratio is now under full control of feature negotiation:
 * Ack Ratio is resolved as a dependency of the selected CCID;
 * if the chosen CCID supports it (i.e. CCID == CCID-2), Ack Ratio is set to
   the default of 2, following RFC 4340, 11.3 - "New connections start with Ack
   Ratio 2 for both endpoints";
 * what happens then is part of another patch set, since it concerns the
   dynamic update of Ack Ratio while the connection is in full flight.

Thanks to Tomasz Grobelny for discussion leading up to this patch.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 Documentation/networking/dccp.txt | 3 ---
 include/linux/dccp.h              | 2 --
 net/dccp/dccp.h                   | 1 -
 net/dccp/minisocks.c              | 1 -
 net/dccp/options.c                | 1 -
 net/dccp/sysctl.c                 | 7 -------
 6 files changed, 15 deletions(-)

(limited to 'Documentation')

diff --git a/Documentation/networking/dccp.txt b/Documentation/networking/dccp.txt
index f0aeb20fa63b..43df4487379b 100644
--- a/Documentation/networking/dccp.txt
+++ b/Documentation/networking/dccp.txt
@@ -125,9 +125,6 @@ send_ndp = 1
 send_ackvec = 1
 	Whether or not to send Ack Vector options (sec. 11.5).
 
-ack_ratio = 2
-	The default Ack Ratio (sec. 11.3) to use.
-
 tx_ccid = 2
 	Default CCID for the sender-receiver half-connection.
 
diff --git a/include/linux/dccp.h b/include/linux/dccp.h
index 5a5a89935dbc..eda389ce04f4 100644
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -368,7 +368,6 @@ static inline unsigned int dccp_hdr_len(const struct sk_buff *skb)
   * @dccpms_ccid - Congestion Control Id (CCID) (section 10)
   * @dccpms_send_ack_vector - Send Ack Vector Feature (section 11.5)
   * @dccpms_send_ndp_count - Send NDP Count Feature (7.7.2)
-  * @dccpms_ack_ratio - Ack Ratio Feature (section 11.3)
   * @dccpms_pending - List of features being negotiated
   * @dccpms_conf -
   */
@@ -378,7 +377,6 @@ struct dccp_minisock {
 	__u8			dccpms_tx_ccid;
 	__u8			dccpms_send_ack_vector;
 	__u8			dccpms_send_ndp_count;
-	__u8			dccpms_ack_ratio;
 	struct list_head	dccpms_pending;
 	struct list_head	dccpms_conf;
 };
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index e656dafb5d96..031ce350d3c1 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -98,7 +98,6 @@ extern int  sysctl_dccp_retries2;
 extern int  sysctl_dccp_feat_sequence_window;
 extern int  sysctl_dccp_feat_rx_ccid;
 extern int  sysctl_dccp_feat_tx_ccid;
-extern int  sysctl_dccp_feat_ack_ratio;
 extern int  sysctl_dccp_feat_send_ack_vector;
 extern int  sysctl_dccp_feat_send_ndp_count;
 extern int  sysctl_dccp_tx_qlen;
diff --git a/net/dccp/minisocks.c b/net/dccp/minisocks.c
index e487133ae079..ee7f40f8ddfa 100644
--- a/net/dccp/minisocks.c
+++ b/net/dccp/minisocks.c
@@ -47,7 +47,6 @@ void dccp_minisock_init(struct dccp_minisock *dmsk)
 	dmsk->dccpms_sequence_window = sysctl_dccp_feat_sequence_window;
 	dmsk->dccpms_rx_ccid	     = sysctl_dccp_feat_rx_ccid;
 	dmsk->dccpms_tx_ccid	     = sysctl_dccp_feat_tx_ccid;
-	dmsk->dccpms_ack_ratio	     = sysctl_dccp_feat_ack_ratio;
 	dmsk->dccpms_send_ack_vector = sysctl_dccp_feat_send_ack_vector;
 	dmsk->dccpms_send_ndp_count  = sysctl_dccp_feat_send_ndp_count;
 }
diff --git a/net/dccp/options.c b/net/dccp/options.c
index 67a171a1268c..515ad45013ad 100644
--- a/net/dccp/options.c
+++ b/net/dccp/options.c
@@ -26,7 +26,6 @@
 int sysctl_dccp_feat_sequence_window = DCCPF_INITIAL_SEQUENCE_WINDOW;
 int sysctl_dccp_feat_rx_ccid	      = DCCPF_INITIAL_CCID;
 int sysctl_dccp_feat_tx_ccid	      = DCCPF_INITIAL_CCID;
-int sysctl_dccp_feat_ack_ratio	      = DCCPF_INITIAL_ACK_RATIO;
 int sysctl_dccp_feat_send_ack_vector = DCCPF_INITIAL_SEND_ACK_VECTOR;
 int sysctl_dccp_feat_send_ndp_count  = DCCPF_INITIAL_SEND_NDP_COUNT;
 
diff --git a/net/dccp/sysctl.c b/net/dccp/sysctl.c
index 21295993fdb8..f6e54f433e29 100644
--- a/net/dccp/sysctl.c
+++ b/net/dccp/sysctl.c
@@ -40,13 +40,6 @@ static struct ctl_table dccp_default_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
-	{
-		.procname	= "ack_ratio",
-		.data		= &sysctl_dccp_feat_ack_ratio,
-		.maxlen		= sizeof(sysctl_dccp_feat_ack_ratio),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
-	},
 	{
 		.procname	= "send_ackvec",
 		.data		= &sysctl_dccp_feat_send_ack_vector,
-- 
cgit v1.2.3


From fade756f18d42694e3acb00e3471ab43002cba16 Mon Sep 17 00:00:00 2001
From: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Date: Thu, 4 Sep 2008 07:30:19 +0200
Subject: dccp: Set per-connection CCIDs via socket options

With this patch, TX/RX CCIDs can now be changed on a per-connection basis, which
overrides the defaults set by the global sysctl variables for TX/RX CCIDs.

To make full use of this facility, the remaining patches of this patch set are
needed, which track dependencies and activate negotiated feature values.

Note on the maximum number of CCIDs that can be registered:
-----------------------------------------------------------
The maximum number of CCIDs that can be registered on the socket is constrained
by the space in a Confirm/Change feature negotiation option.

The space in these in turn depends on the size of header options as defined
in RFC 4340, 5.8. Since this is a recurring constant, it has been moved from
ackvec.h into linux/dccp.h, clarifying its purpose.

Relative to this size, the maximum number of CCID identifiers that can be
present in a Confirm option (which always consumes 1 byte more than a Change
option, cf. 6.1) is 2 bytes less than the maximum TLV size: one for the
CCID-feature-type and one for the selected value.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
---
 Documentation/networking/dccp.txt | 14 ++++++++++++++
 include/linux/dccp.h              |  5 +++++
 net/dccp/ackvec.c                 |  9 ++++-----
 net/dccp/ackvec.h                 |  5 ++---
 net/dccp/feat.h                   |  2 ++
 net/dccp/proto.c                  | 34 ++++++++++++++++++++++++++++++++++
 6 files changed, 61 insertions(+), 8 deletions(-)

(limited to 'Documentation')

diff --git a/Documentation/networking/dccp.txt b/Documentation/networking/dccp.txt
index 43df4487379b..610083ff73f6 100644
--- a/Documentation/networking/dccp.txt
+++ b/Documentation/networking/dccp.txt
@@ -61,6 +61,20 @@ DCCP_SOCKOPT_AVAILABLE_CCIDS is also read-only and returns the list of CCIDs
 supported by the endpoint (see include/linux/dccp.h for symbolic constants).
 The caller needs to provide a sufficiently large (> 2) array of type uint8_t.
 
+DCCP_SOCKOPT_CCID is write-only and sets both the TX and RX CCIDs at the same
+time, combining the operation of the next two socket options. This option is
+preferrable over the latter two, since often applications will use the same
+type of CCID for both directions; and mixed use of CCIDs is not currently well
+understood. This socket option takes as argument at least one uint8_t value, or
+an array of uint8_t values, which must match available CCIDS (see above). CCIDs
+must be registered on the socket before calling connect() or listen().
+
+DCCP_SOCKOPT_TX_CCID is read/write. It returns the current CCID (if set) or sets
+the preference list for the TX CCID, using the same format as DCCP_SOCKOPT_CCID.
+Please note that the getsockopt argument type here is `int', not uint8_t.
+
+DCCP_SOCKOPT_RX_CCID is analogous to DCCP_SOCKOPT_TX_CCID, but for the RX CCID.
+
 DCCP_SOCKOPT_SERVER_TIMEWAIT enables the server (listening socket) to hold
 timewait state when closing the connection (RFC 4340, 8.3). The usual case is
 that the closing server sends a CloseReq, whereupon the client holds timewait
diff --git a/include/linux/dccp.h b/include/linux/dccp.h
index eda389ce04f4..6a72ff52a8a4 100644
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -168,6 +168,8 @@ enum {
 	DCCPO_MIN_CCID_SPECIFIC = 128,
 	DCCPO_MAX_CCID_SPECIFIC = 255,
 };
+/* maximum size of a single TLV-encoded DCCP option (sans type/len bytes) */
+#define DCCP_SINGLE_OPT_MAXLEN	253
 
 /* DCCP CCIDS */
 enum {
@@ -203,6 +205,9 @@ enum dccp_feature_numbers {
 #define DCCP_SOCKOPT_SEND_CSCOV		10
 #define DCCP_SOCKOPT_RECV_CSCOV		11
 #define DCCP_SOCKOPT_AVAILABLE_CCIDS	12
+#define DCCP_SOCKOPT_CCID		13
+#define DCCP_SOCKOPT_TX_CCID		14
+#define DCCP_SOCKOPT_RX_CCID		15
 #define DCCP_SOCKOPT_CCID_RX_INFO	128
 #define DCCP_SOCKOPT_CCID_TX_INFO	192
 
diff --git a/net/dccp/ackvec.c b/net/dccp/ackvec.c
index 1e8be246ad15..01e4d39fa232 100644
--- a/net/dccp/ackvec.c
+++ b/net/dccp/ackvec.c
@@ -12,7 +12,6 @@
 #include "ackvec.h"
 #include "dccp.h"
 
-#include <linux/dccp.h>
 #include <linux/init.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
@@ -68,7 +67,7 @@ int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
 	struct dccp_sock *dp = dccp_sk(sk);
 	struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
 	/* Figure out how many options do we need to represent the ackvec */
-	const u16 nr_opts = DIV_ROUND_UP(av->av_vec_len, DCCP_MAX_ACKVEC_OPT_LEN);
+	const u8 nr_opts = DIV_ROUND_UP(av->av_vec_len, DCCP_SINGLE_OPT_MAXLEN);
 	u16 len = av->av_vec_len + 2 * nr_opts, i;
 	u32 elapsed_time;
 	const unsigned char *tail, *from;
@@ -100,8 +99,8 @@ int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
 	for (i = 0; i < nr_opts; ++i) {
 		int copylen = len;
 
-		if (len > DCCP_MAX_ACKVEC_OPT_LEN)
-			copylen = DCCP_MAX_ACKVEC_OPT_LEN;
+		if (len > DCCP_SINGLE_OPT_MAXLEN)
+			copylen = DCCP_SINGLE_OPT_MAXLEN;
 
 		*to++ = DCCPO_ACK_VECTOR_0;
 		*to++ = copylen + 2;
@@ -432,7 +431,7 @@ found:
 int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb,
 		      u64 *ackno, const u8 opt, const u8 *value, const u8 len)
 {
-	if (len > DCCP_MAX_ACKVEC_OPT_LEN)
+	if (len > DCCP_SINGLE_OPT_MAXLEN)
 		return -1;
 
 	/* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */
diff --git a/net/dccp/ackvec.h b/net/dccp/ackvec.h
index bcb64fb4acef..4ccee030524e 100644
--- a/net/dccp/ackvec.h
+++ b/net/dccp/ackvec.h
@@ -11,15 +11,14 @@
  *	published by the Free Software Foundation.
  */
 
+#include <linux/dccp.h>
 #include <linux/compiler.h>
 #include <linux/ktime.h>
 #include <linux/list.h>
 #include <linux/types.h>
 
-/* Read about the ECN nonce to see why it is 253 */
-#define DCCP_MAX_ACKVEC_OPT_LEN 253
 /* We can spread an ack vector across multiple options */
-#define DCCP_MAX_ACKVEC_LEN (DCCP_MAX_ACKVEC_OPT_LEN * 2)
+#define DCCP_MAX_ACKVEC_LEN (DCCP_SINGLE_OPT_MAXLEN * 2)
 
 #define DCCP_ACKVEC_STATE_RECEIVED	0
 #define DCCP_ACKVEC_STATE_ECN_MARKED	(1 << 6)
diff --git a/net/dccp/feat.h b/net/dccp/feat.h
index 2c92bd18e5f4..b53b11717c40 100644
--- a/net/dccp/feat.h
+++ b/net/dccp/feat.h
@@ -22,6 +22,8 @@
 /* Wmin=32 and Wmax=2^46-1 from 7.5.2 */
 #define DCCPF_SEQ_WMIN		32
 #define DCCPF_SEQ_WMAX		0x3FFFFFFFFFFFull
+/* Maximum number of SP values that fit in a single (Confirm) option */
+#define DCCP_FEAT_MAX_SP_VALS	(DCCP_SINGLE_OPT_MAXLEN - 2)
 
 enum dccp_feat_type {
 	FEAT_AT_RX   = 1,	/* located at RX side of half-connection  */
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index e29bbf914057..2cd56df44d8e 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -506,6 +506,36 @@ static int dccp_setsockopt_cscov(struct sock *sk, int cscov, bool rx)
 	return rc;
 }
 
+static int dccp_setsockopt_ccid(struct sock *sk, int type,
+				char __user *optval, int optlen)
+{
+	u8 *val;
+	int rc = 0;
+
+	if (optlen < 1 || optlen > DCCP_FEAT_MAX_SP_VALS)
+		return -EINVAL;
+
+	val = kmalloc(optlen, GFP_KERNEL);
+	if (val == NULL)
+		return -ENOMEM;
+
+	if (copy_from_user(val, optval, optlen)) {
+		kfree(val);
+		return -EFAULT;
+	}
+
+	lock_sock(sk);
+	if (type == DCCP_SOCKOPT_TX_CCID || type == DCCP_SOCKOPT_CCID)
+		rc = dccp_feat_register_sp(sk, DCCPF_CCID, 1, val, optlen);
+
+	if (!rc && (type == DCCP_SOCKOPT_RX_CCID || type == DCCP_SOCKOPT_CCID))
+		rc = dccp_feat_register_sp(sk, DCCPF_CCID, 0, val, optlen);
+	release_sock(sk);
+
+	kfree(val);
+	return rc;
+}
+
 static int do_dccp_setsockopt(struct sock *sk, int level, int optname,
 		char __user *optval, int optlen)
 {
@@ -520,6 +550,10 @@ static int do_dccp_setsockopt(struct sock *sk, int level, int optname,
 	case DCCP_SOCKOPT_CHANGE_R:
 		DCCP_WARN("sockopt(CHANGE_L/R) is deprecated: fix your app\n");
 		return 0;
+	case DCCP_SOCKOPT_CCID:
+	case DCCP_SOCKOPT_RX_CCID:
+	case DCCP_SOCKOPT_TX_CCID:
+		return dccp_setsockopt_ccid(sk, optname, optval, optlen);
 	}
 
 	if (optlen < (int)sizeof(int))
-- 
cgit v1.2.3


From 78673e24df27c76ec75565f4024d45c2c74ef148 Mon Sep 17 00:00:00 2001
From: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Date: Thu, 4 Sep 2008 07:30:19 +0200
Subject: dccp: Remove obsolete parts of the old CCID interface

The TX/RX CCIDs of the minisock are now redundant: similar to the Ack Vector
case, their value equals initially that of the sysctl, but at the end of
feature negotiation may be something different.

The old interface removed by this patch thus has been replaced by the newer
interface to dynamically query the currently loaded CCIDs earlier in this
patch set.

Also removed the constructors for the TX CCID and the RX CCID, since the
switch rx/non-rx is done by the handler in minisocks.c (and the handler is
the only place in the code where CCIDs are loaded).

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
---
 Documentation/networking/dccp.txt |  5 +++--
 include/linux/dccp.h              |  3 ---
 net/dccp/ccid.c                   | 14 --------------
 net/dccp/ccid.h                   |  5 -----
 net/dccp/feat.c                   | 12 ------------
 net/dccp/minisocks.c              |  2 --
 6 files changed, 3 insertions(+), 38 deletions(-)

(limited to 'Documentation')

diff --git a/Documentation/networking/dccp.txt b/Documentation/networking/dccp.txt
index 610083ff73f6..a203d132dbef 100644
--- a/Documentation/networking/dccp.txt
+++ b/Documentation/networking/dccp.txt
@@ -140,10 +140,11 @@ send_ackvec = 1
 	Whether or not to send Ack Vector options (sec. 11.5).
 
 tx_ccid = 2
-	Default CCID for the sender-receiver half-connection.
+	Default CCID for the sender-receiver half-connection. Depending on the
+	choice of CCID, the Send Ack Vector feature is enabled automatically.
 
 rx_ccid = 2
-	Default CCID for the receiver-sender half-connection.
+	Default CCID for the receiver-sender half-connection; see tx_ccid.
 
 seq_window = 100
 	The initial sequence window (sec. 7.5.2).
diff --git a/include/linux/dccp.h b/include/linux/dccp.h
index 6a72ff52a8a4..46daea312d92 100644
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -370,7 +370,6 @@ static inline unsigned int dccp_hdr_len(const struct sk_buff *skb)
   * Will be used to pass the state from dccp_request_sock to dccp_sock.
   *
   * @dccpms_sequence_window - Sequence Window Feature (section 7.5.2)
-  * @dccpms_ccid - Congestion Control Id (CCID) (section 10)
   * @dccpms_send_ack_vector - Send Ack Vector Feature (section 11.5)
   * @dccpms_send_ndp_count - Send NDP Count Feature (7.7.2)
   * @dccpms_pending - List of features being negotiated
@@ -378,8 +377,6 @@ static inline unsigned int dccp_hdr_len(const struct sk_buff *skb)
   */
 struct dccp_minisock {
 	__u64			dccpms_sequence_window;
-	__u8			dccpms_rx_ccid;
-	__u8			dccpms_tx_ccid;
 	__u8			dccpms_send_ack_vector;
 	__u8			dccpms_send_ndp_count;
 	struct list_head	dccpms_pending;
diff --git a/net/dccp/ccid.c b/net/dccp/ccid.c
index f72ca83df552..330372a1a0b6 100644
--- a/net/dccp/ccid.c
+++ b/net/dccp/ccid.c
@@ -253,20 +253,6 @@ out_module_put:
 
 EXPORT_SYMBOL_GPL(ccid_new);
 
-struct ccid *ccid_hc_rx_new(unsigned char id, struct sock *sk, gfp_t gfp)
-{
-	return ccid_new(id, sk, 1, gfp);
-}
-
-EXPORT_SYMBOL_GPL(ccid_hc_rx_new);
-
-struct ccid *ccid_hc_tx_new(unsigned char id,struct sock *sk,  gfp_t gfp)
-{
-	return ccid_new(id, sk, 0, gfp);
-}
-
-EXPORT_SYMBOL_GPL(ccid_hc_tx_new);
-
 static void ccid_delete(struct ccid *ccid, struct sock *sk, int rx)
 {
 	struct ccid_operations *ccid_ops;
diff --git a/net/dccp/ccid.h b/net/dccp/ccid.h
index 803343aed004..18f69423a708 100644
--- a/net/dccp/ccid.h
+++ b/net/dccp/ccid.h
@@ -111,11 +111,6 @@ extern int  ccid_getsockopt_builtin_ccids(struct sock *sk, int len,
 extern struct ccid *ccid_new(unsigned char id, struct sock *sk, int rx,
 			     gfp_t gfp);
 
-extern struct ccid *ccid_hc_rx_new(unsigned char id, struct sock *sk,
-				   gfp_t gfp);
-extern struct ccid *ccid_hc_tx_new(unsigned char id, struct sock *sk,
-				   gfp_t gfp);
-
 static inline int ccid_get_current_rx_ccid(struct dccp_sock *dp)
 {
 	struct ccid *ccid = dp->dccps_hc_rx_ccid;
diff --git a/net/dccp/feat.c b/net/dccp/feat.c
index 6c82dea409d9..cb2ddd2b894b 100644
--- a/net/dccp/feat.c
+++ b/net/dccp/feat.c
@@ -1119,18 +1119,6 @@ int dccp_feat_init(struct sock *sk)
 	INIT_LIST_HEAD(&dmsk->dccpms_pending);	/* XXX no longer used */
 	INIT_LIST_HEAD(&dmsk->dccpms_conf);	/* XXX no longer used */
 
-	/* CCID L */
-	rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 1, 0,
-				&dmsk->dccpms_tx_ccid, 1);
-	if (rc)
-		goto out;
-
-	/* CCID R */
-	rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 0, 0,
-				&dmsk->dccpms_rx_ccid, 1);
-	if (rc)
-		goto out;
-
 	/* Ack ratio */
 	rc = __feat_register_nn(&dp->dccps_featneg, DCCPF_ACK_RATIO, 0,
 				dp->dccps_l_ack_ratio);
diff --git a/net/dccp/minisocks.c b/net/dccp/minisocks.c
index 258195972bce..486d61df2604 100644
--- a/net/dccp/minisocks.c
+++ b/net/dccp/minisocks.c
@@ -45,8 +45,6 @@ EXPORT_SYMBOL_GPL(dccp_death_row);
 void dccp_minisock_init(struct dccp_minisock *dmsk)
 {
 	dmsk->dccpms_sequence_window = sysctl_dccp_feat_sequence_window;
-	dmsk->dccpms_rx_ccid	     = sysctl_dccp_feat_rx_ccid;
-	dmsk->dccpms_tx_ccid	     = sysctl_dccp_feat_tx_ccid;
 	dmsk->dccpms_send_ack_vector = sysctl_dccp_feat_send_ack_vector;
 	dmsk->dccpms_send_ndp_count  = sysctl_dccp_feat_send_ndp_count;
 }
-- 
cgit v1.2.3


From 68e074bfcef269bc61006c2740d7f89ccbbd93d7 Mon Sep 17 00:00:00 2001
From: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Date: Thu, 4 Sep 2008 07:30:19 +0200
Subject: dccp: Remove manual influence on NDP Count feature

Updating the NDP count feature is handled automatically now:
 * for CCID-2 it is disabled, since the code does not use NDP counts;
 * for CCID-3 it is enabled, as NDP counts are used to determine loss lengths.

Allowing the user to change NDP values leads to unpredictable and failing
behaviour, since it is then possible to disable NDP counts even when they
are needed (e.g. in CCID-3).

This means that only those user settings are sensible that agree with the
values for Send NDP Count implied by the choice of CCID. But those settings
are already activated by the feature negotiation (CCID dependency tracking),
hence this form of support is redundant.

At startup the initialisation of the NDP count feature is with the default
value of 0, which is done implicitly by the zeroing-out of the socket when
it is allocated. If the choice of CCID or feature negotiation enables NDP
count, this will then be updated via the NDP activation handler.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
---
 Documentation/networking/dccp.txt | 3 ---
 include/linux/dccp.h              | 4 ++--
 net/dccp/dccp.h                   | 1 -
 net/dccp/feat.c                   | 2 +-
 net/dccp/minisocks.c              | 1 -
 net/dccp/options.c                | 4 +---
 net/dccp/sysctl.c                 | 7 -------
 7 files changed, 4 insertions(+), 18 deletions(-)

(limited to 'Documentation')

diff --git a/Documentation/networking/dccp.txt b/Documentation/networking/dccp.txt
index a203d132dbef..1403745ab406 100644
--- a/Documentation/networking/dccp.txt
+++ b/Documentation/networking/dccp.txt
@@ -133,9 +133,6 @@ retries2
 	importance for retransmitted acknowledgments and feature negotiation,
 	data packets are never retransmitted. Analogue of tcp_retries2.
 
-send_ndp = 1
-	Whether or not to send NDP count options (sec. 7.7.2).
-
 send_ackvec = 1
 	Whether or not to send Ack Vector options (sec. 11.5).
 
diff --git a/include/linux/dccp.h b/include/linux/dccp.h
index 46daea312d92..60e94438eadd 100644
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -371,14 +371,12 @@ static inline unsigned int dccp_hdr_len(const struct sk_buff *skb)
   *
   * @dccpms_sequence_window - Sequence Window Feature (section 7.5.2)
   * @dccpms_send_ack_vector - Send Ack Vector Feature (section 11.5)
-  * @dccpms_send_ndp_count - Send NDP Count Feature (7.7.2)
   * @dccpms_pending - List of features being negotiated
   * @dccpms_conf -
   */
 struct dccp_minisock {
 	__u64			dccpms_sequence_window;
 	__u8			dccpms_send_ack_vector;
-	__u8			dccpms_send_ndp_count;
 	struct list_head	dccpms_pending;
 	struct list_head	dccpms_conf;
 };
@@ -490,6 +488,7 @@ struct dccp_ackvec;
  * @dccps_r_ack_ratio - feature-remote Ack Ratio
  * @dccps_pcslen - sender   partial checksum coverage (via sockopt)
  * @dccps_pcrlen - receiver partial checksum coverage (via sockopt)
+ * @dccps_send_ndp_count - local Send NDP Count feature (7.7.2)
  * @dccps_ndp_count - number of Non Data Packets since last data packet
  * @dccps_mss_cache - current value of MSS (path MTU minus header sizes)
  * @dccps_rate_last - timestamp for rate-limiting DCCP-Sync (RFC 4340, 7.5.4)
@@ -529,6 +528,7 @@ struct dccp_sock {
 	__u16				dccps_r_ack_ratio;
 	__u8				dccps_pcslen:4;
 	__u8				dccps_pcrlen:4;
+	__u8				dccps_send_ndp_count:1;
 	__u64				dccps_ndp_count:48;
 	unsigned long			dccps_rate_last;
 	struct dccp_minisock		dccps_minisock;
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index 1baed789bcc2..51436c825655 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -99,7 +99,6 @@ extern int  sysctl_dccp_feat_sequence_window;
 extern int  sysctl_dccp_feat_rx_ccid;
 extern int  sysctl_dccp_feat_tx_ccid;
 extern int  sysctl_dccp_feat_send_ack_vector;
-extern int  sysctl_dccp_feat_send_ndp_count;
 extern int  sysctl_dccp_tx_qlen;
 extern int  sysctl_dccp_sync_ratelimit;
 
diff --git a/net/dccp/feat.c b/net/dccp/feat.c
index cb2ddd2b894b..35a57ab3bb1e 100644
--- a/net/dccp/feat.c
+++ b/net/dccp/feat.c
@@ -86,7 +86,7 @@ static int dccp_hdlr_ackvec(struct sock *sk, u64 enable, bool rx)
 static int dccp_hdlr_ndp(struct sock *sk, u64 enable, bool rx)
 {
 	if (!rx)
-		dccp_msk(sk)->dccpms_send_ndp_count = (enable > 0);
+		dccp_sk(sk)->dccps_send_ndp_count = (enable > 0);
 	return 0;
 }
 
diff --git a/net/dccp/minisocks.c b/net/dccp/minisocks.c
index 486d61df2604..9e2232572662 100644
--- a/net/dccp/minisocks.c
+++ b/net/dccp/minisocks.c
@@ -46,7 +46,6 @@ void dccp_minisock_init(struct dccp_minisock *dmsk)
 {
 	dmsk->dccpms_sequence_window = sysctl_dccp_feat_sequence_window;
 	dmsk->dccpms_send_ack_vector = sysctl_dccp_feat_send_ack_vector;
-	dmsk->dccpms_send_ndp_count  = sysctl_dccp_feat_send_ndp_count;
 }
 
 void dccp_time_wait(struct sock *sk, int state, int timeo)
diff --git a/net/dccp/options.c b/net/dccp/options.c
index 3a9a22f0ac1a..6b0704497e83 100644
--- a/net/dccp/options.c
+++ b/net/dccp/options.c
@@ -27,7 +27,6 @@ int sysctl_dccp_feat_sequence_window = DCCPF_INITIAL_SEQUENCE_WINDOW;
 int sysctl_dccp_feat_rx_ccid	      = DCCPF_INITIAL_CCID;
 int sysctl_dccp_feat_tx_ccid	      = DCCPF_INITIAL_CCID;
 int sysctl_dccp_feat_send_ack_vector = DCCPF_INITIAL_SEND_ACK_VECTOR;
-int sysctl_dccp_feat_send_ndp_count  = DCCPF_INITIAL_SEND_NDP_COUNT;
 
 u64 dccp_decode_value_var(const u8 *bf, const u8 len)
 {
@@ -531,8 +530,7 @@ int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
 
 	DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
 
-	if (dmsk->dccpms_send_ndp_count &&
-	    dccp_insert_option_ndp(sk, skb))
+	if (dp->dccps_send_ndp_count && dccp_insert_option_ndp(sk, skb))
 		return -1;
 
 	if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA) {
diff --git a/net/dccp/sysctl.c b/net/dccp/sysctl.c
index f6e54f433e29..587c12f915c1 100644
--- a/net/dccp/sysctl.c
+++ b/net/dccp/sysctl.c
@@ -47,13 +47,6 @@ static struct ctl_table dccp_default_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
-	{
-		.procname	= "send_ndp",
-		.data		= &sysctl_dccp_feat_send_ndp_count,
-		.maxlen		= sizeof(sysctl_dccp_feat_send_ndp_count),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
-	},
 	{
 		.procname	= "request_retries",
 		.data		= &sysctl_dccp_request_retries,
-- 
cgit v1.2.3


From b235dc4abbc1356284bd0dc730efa711f394e0e2 Mon Sep 17 00:00:00 2001
From: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Date: Thu, 4 Sep 2008 07:30:19 +0200
Subject: dccp ccid-2: Phase out the use of boolean Ack Vector sysctl

This removes the use of the sysctl and the minisock variable for the Send Ack
Vector feature, which is now handled fully dynamically via feature negotiation;
i.e. when CCID2 is enabled, Ack Vectors are automatically enabled (as per
RFC 4341, 4.).

Using a sysctl in parallel to this implementation would open the door to
crashes, since much of the code relies on tests of the boolean minisock /
sysctl variable. Thus, this patch replaces all tests of type

	if (dccp_msk(sk)->dccpms_send_ack_vector)
		/* ... */
with
	if (dp->dccps_hc_rx_ackvec != NULL)
		/* ... */

The dccps_hc_rx_ackvec is allocated by the dccp_hdlr_ackvec() when feature
negotiation concluded that Ack Vectors are to be used on the half-connection.
Otherwise, it is NULL (due to dccp_init_sock/dccp_create_openreq_child),
so that the test is a valid one.

The activation handler for Ack Vectors is called as soon as the feature
negotiation has concluded at the
 * server when the Ack marking the transition RESPOND => OPEN arrives;
 * client after it has sent its ACK, marking the transition REQUEST => PARTOPEN.

Adding the sequence number of the Response packet to the Ack Vector has been
removed, since
 (a) connection establishment implies that the Response has been received;
 (b) the CCIDs only look at packets received in the (PART)OPEN state, i.e.
     this entry will always be ignored;
 (c) it can not be used for anything useful - to detect loss for instance, only
     packets received after the loss can serve as pseudo-dupacks.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
---
 Documentation/networking/dccp.txt |  3 ---
 include/linux/dccp.h              |  3 ---
 net/dccp/dccp.h                   |  3 +--
 net/dccp/diag.c                   |  2 +-
 net/dccp/input.c                  | 12 +++---------
 net/dccp/minisocks.c              |  1 -
 net/dccp/options.c                |  7 ++-----
 net/dccp/proto.c                  |  3 +--
 net/dccp/sysctl.c                 |  7 -------
 9 files changed, 8 insertions(+), 33 deletions(-)

(limited to 'Documentation')

diff --git a/Documentation/networking/dccp.txt b/Documentation/networking/dccp.txt
index 1403745ab406..7a3bb1abb830 100644
--- a/Documentation/networking/dccp.txt
+++ b/Documentation/networking/dccp.txt
@@ -133,9 +133,6 @@ retries2
 	importance for retransmitted acknowledgments and feature negotiation,
 	data packets are never retransmitted. Analogue of tcp_retries2.
 
-send_ackvec = 1
-	Whether or not to send Ack Vector options (sec. 11.5).
-
 tx_ccid = 2
 	Default CCID for the sender-receiver half-connection. Depending on the
 	choice of CCID, the Send Ack Vector feature is enabled automatically.
diff --git a/include/linux/dccp.h b/include/linux/dccp.h
index 60e94438eadd..61734e27abb7 100644
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -360,7 +360,6 @@ static inline unsigned int dccp_hdr_len(const struct sk_buff *skb)
 #define DCCPF_INITIAL_SEQUENCE_WINDOW		100
 #define DCCPF_INITIAL_ACK_RATIO			2
 #define DCCPF_INITIAL_CCID			DCCPC_CCID2
-#define DCCPF_INITIAL_SEND_ACK_VECTOR		1
 /* FIXME: for now we're default to 1 but it should really be 0 */
 #define DCCPF_INITIAL_SEND_NDP_COUNT		1
 
@@ -370,13 +369,11 @@ static inline unsigned int dccp_hdr_len(const struct sk_buff *skb)
   * Will be used to pass the state from dccp_request_sock to dccp_sock.
   *
   * @dccpms_sequence_window - Sequence Window Feature (section 7.5.2)
-  * @dccpms_send_ack_vector - Send Ack Vector Feature (section 11.5)
   * @dccpms_pending - List of features being negotiated
   * @dccpms_conf -
   */
 struct dccp_minisock {
 	__u64			dccpms_sequence_window;
-	__u8			dccpms_send_ack_vector;
 	struct list_head	dccpms_pending;
 	struct list_head	dccpms_conf;
 };
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index 51436c825655..3fd16e82c003 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -98,7 +98,6 @@ extern int  sysctl_dccp_retries2;
 extern int  sysctl_dccp_feat_sequence_window;
 extern int  sysctl_dccp_feat_rx_ccid;
 extern int  sysctl_dccp_feat_tx_ccid;
-extern int  sysctl_dccp_feat_send_ack_vector;
 extern int  sysctl_dccp_tx_qlen;
 extern int  sysctl_dccp_sync_ratelimit;
 
@@ -434,7 +433,7 @@ static inline int dccp_ack_pending(const struct sock *sk)
 	const struct dccp_sock *dp = dccp_sk(sk);
 	return dp->dccps_timestamp_echo != 0 ||
 #ifdef CONFIG_IP_DCCP_ACKVEC
-	       (dccp_msk(sk)->dccpms_send_ack_vector &&
+	       (dp->dccps_hc_rx_ackvec != NULL &&
 		dccp_ackvec_pending(dp->dccps_hc_rx_ackvec)) ||
 #endif
 	       inet_csk_ack_scheduled(sk);
diff --git a/net/dccp/diag.c b/net/dccp/diag.c
index d8a3509b26f6..93aae7c95550 100644
--- a/net/dccp/diag.c
+++ b/net/dccp/diag.c
@@ -29,7 +29,7 @@ static void dccp_get_info(struct sock *sk, struct tcp_info *info)
 	info->tcpi_backoff	= icsk->icsk_backoff;
 	info->tcpi_pmtu		= icsk->icsk_pmtu_cookie;
 
-	if (dccp_msk(sk)->dccpms_send_ack_vector)
+	if (dp->dccps_hc_rx_ackvec != NULL)
 		info->tcpi_options |= TCPI_OPT_SACK;
 
 	ccid_hc_rx_get_info(dp->dccps_hc_rx_ccid, sk, info);
diff --git a/net/dccp/input.c b/net/dccp/input.c
index 0672b7e1763e..5eb443f656c1 100644
--- a/net/dccp/input.c
+++ b/net/dccp/input.c
@@ -163,7 +163,7 @@ static void dccp_event_ack_recv(struct sock *sk, struct sk_buff *skb)
 {
 	struct dccp_sock *dp = dccp_sk(sk);
 
-	if (dccp_msk(sk)->dccpms_send_ack_vector)
+	if (dp->dccps_hc_rx_ackvec != NULL)
 		dccp_ackvec_check_rcv_ackno(dp->dccps_hc_rx_ackvec, sk,
 					    DCCP_SKB_CB(skb)->dccpd_ack_seq);
 }
@@ -375,7 +375,7 @@ int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
 	if (DCCP_SKB_CB(skb)->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 		dccp_event_ack_recv(sk, skb);
 
-	if (dccp_msk(sk)->dccpms_send_ack_vector &&
+	if (dp->dccps_hc_rx_ackvec != NULL &&
 	    dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
 			    DCCP_SKB_CB(skb)->dccpd_seq,
 			    DCCP_ACKVEC_STATE_RECEIVED))
@@ -434,12 +434,6 @@ static int dccp_rcv_request_sent_state_process(struct sock *sk,
 			dp->dccps_syn_rtt = dccp_sample_rtt(sk, 10 * (tstamp -
 			    dp->dccps_options_received.dccpor_timestamp_echo));
 
-		if (dccp_msk(sk)->dccpms_send_ack_vector &&
-		    dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
-				    DCCP_SKB_CB(skb)->dccpd_seq,
-				    DCCP_ACKVEC_STATE_RECEIVED))
-			goto out_invalid_packet; /* FIXME: change error code */
-
 		/* Stop the REQUEST timer */
 		inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
 		WARN_ON(sk->sk_send_head == NULL);
@@ -637,7 +631,7 @@ int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 		if (dcb->dccpd_ack_seq != DCCP_PKT_WITHOUT_ACK_SEQ)
 			dccp_event_ack_recv(sk, skb);
 
-		if (dccp_msk(sk)->dccpms_send_ack_vector &&
+		if (dp->dccps_hc_rx_ackvec != NULL &&
 		    dccp_ackvec_add(dp->dccps_hc_rx_ackvec, sk,
 				    DCCP_SKB_CB(skb)->dccpd_seq,
 				    DCCP_ACKVEC_STATE_RECEIVED))
diff --git a/net/dccp/minisocks.c b/net/dccp/minisocks.c
index 9e2232572662..0ebf8ebcf3de 100644
--- a/net/dccp/minisocks.c
+++ b/net/dccp/minisocks.c
@@ -45,7 +45,6 @@ EXPORT_SYMBOL_GPL(dccp_death_row);
 void dccp_minisock_init(struct dccp_minisock *dmsk)
 {
 	dmsk->dccpms_sequence_window = sysctl_dccp_feat_sequence_window;
-	dmsk->dccpms_send_ack_vector = sysctl_dccp_feat_send_ack_vector;
 }
 
 void dccp_time_wait(struct sock *sk, int state, int timeo)
diff --git a/net/dccp/options.c b/net/dccp/options.c
index 6b0704497e83..aca309e16632 100644
--- a/net/dccp/options.c
+++ b/net/dccp/options.c
@@ -26,7 +26,6 @@
 int sysctl_dccp_feat_sequence_window = DCCPF_INITIAL_SEQUENCE_WINDOW;
 int sysctl_dccp_feat_rx_ccid	      = DCCPF_INITIAL_CCID;
 int sysctl_dccp_feat_tx_ccid	      = DCCPF_INITIAL_CCID;
-int sysctl_dccp_feat_send_ack_vector = DCCPF_INITIAL_SEND_ACK_VECTOR;
 
 u64 dccp_decode_value_var(const u8 *bf, const u8 len)
 {
@@ -145,8 +144,7 @@ int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
 		case DCCPO_ACK_VECTOR_1:
 			if (dccp_packet_without_ack(skb))   /* RFC 4340, 11.4 */
 				break;
-
-			if (dccp_msk(sk)->dccpms_send_ack_vector &&
+			if (dp->dccps_hc_rx_ackvec != NULL &&
 			    dccp_ackvec_parse(sk, skb, &ackno, opt, value, len))
 				goto out_invalid_option;
 			break;
@@ -526,7 +524,6 @@ static void dccp_insert_option_padding(struct sk_buff *skb)
 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
 {
 	struct dccp_sock *dp = dccp_sk(sk);
-	struct dccp_minisock *dmsk = dccp_msk(sk);
 
 	DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
 
@@ -547,7 +544,7 @@ int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
 			if (dccp_insert_option_timestamp(sk, skb))
 				return -1;
 
-		} else if (dmsk->dccpms_send_ack_vector	&&
+		} else if (dp->dccps_hc_rx_ackvec != NULL &&
 			   dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) &&
 			   dccp_insert_option_ackvec(sk, skb)) {
 				return -1;
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index 0d420790b795..775eaa3d0c49 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -207,7 +207,6 @@ EXPORT_SYMBOL_GPL(dccp_init_sock);
 void dccp_destroy_sock(struct sock *sk)
 {
 	struct dccp_sock *dp = dccp_sk(sk);
-	struct dccp_minisock *dmsk = dccp_msk(sk);
 
 	/*
 	 * DCCP doesn't use sk_write_queue, just sk_send_head
@@ -225,7 +224,7 @@ void dccp_destroy_sock(struct sock *sk)
 	kfree(dp->dccps_service_list);
 	dp->dccps_service_list = NULL;
 
-	if (dmsk->dccpms_send_ack_vector) {
+	if (dp->dccps_hc_rx_ackvec != NULL) {
 		dccp_ackvec_free(dp->dccps_hc_rx_ackvec);
 		dp->dccps_hc_rx_ackvec = NULL;
 	}
diff --git a/net/dccp/sysctl.c b/net/dccp/sysctl.c
index 587c12f915c1..018e210875e1 100644
--- a/net/dccp/sysctl.c
+++ b/net/dccp/sysctl.c
@@ -40,13 +40,6 @@ static struct ctl_table dccp_default_table[] = {
 		.mode		= 0644,
 		.proc_handler	= proc_dointvec,
 	},
-	{
-		.procname	= "send_ackvec",
-		.data		= &sysctl_dccp_feat_send_ack_vector,
-		.maxlen		= sizeof(sysctl_dccp_feat_send_ack_vector),
-		.mode		= 0644,
-		.proc_handler	= proc_dointvec,
-	},
 	{
 		.procname	= "request_retries",
 		.data		= &sysctl_dccp_request_retries,
-- 
cgit v1.2.3


From 51c7d4fa2675c106a980ddcdbe308b54b5151945 Mon Sep 17 00:00:00 2001
From: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Date: Thu, 4 Sep 2008 07:30:19 +0200
Subject: dccp: Implement both feature-local and feature-remote Sequence Window
 feature

This adds full support for local/remote Sequence Window feature, from which the
  * sequence-number-validity (W) and
  * acknowledgment-number-validity (W') windows
derive as specified in RFC 4340, 7.5.3.

Specifically, the following changes are introduced:
  * integrated new socket fields into dccp_sk;
  * updated the update_gsr/gss routines with regard to these fields;
  * updated handler code: the Sequence Window feature is located at the TX side,
    so the local feature is meant if the handler-rx flag is false;
  * the initialisation of `rcv_wnd' in reqsk is removed, since
    - rcv_wnd is not used by the code anywhere;
    - sequence number checks are not done in the LISTEN state (cf. 7.5.3);
    - dccp_check_req checks the Ack number validity more rigorously;
  * the `struct dccp_minisock' became empty and is now removed.

Until the handshake completes with activating negotiated values, the local/remote
Sequence-Window values are undefined and thus can not reliably be estimated.
This issue is addressed in a separate patch.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
---
 Documentation/networking/dccp.txt |  3 ++-
 include/linux/dccp.h              | 24 ++++--------------------
 net/dccp/dccp.h                   | 16 +++++++---------
 net/dccp/feat.c                   | 13 +++++++++++--
 net/dccp/minisocks.c              | 11 -----------
 net/dccp/proto.c                  |  2 --
 6 files changed, 24 insertions(+), 45 deletions(-)

(limited to 'Documentation')

diff --git a/Documentation/networking/dccp.txt b/Documentation/networking/dccp.txt
index 7a3bb1abb830..b132e4a3cf0f 100644
--- a/Documentation/networking/dccp.txt
+++ b/Documentation/networking/dccp.txt
@@ -141,7 +141,8 @@ rx_ccid = 2
 	Default CCID for the receiver-sender half-connection; see tx_ccid.
 
 seq_window = 100
-	The initial sequence window (sec. 7.5.2).
+	The initial sequence window (sec. 7.5.2) of the sender. This influences
+	the local ackno validity and the remote seqno validity windows (7.5.1).
 
 tx_qlen = 5
 	The size of the transmit buffer in packets. A value of 0 corresponds
diff --git a/include/linux/dccp.h b/include/linux/dccp.h
index 990e97fa1f07..7a0502ab383a 100644
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -363,19 +363,6 @@ static inline unsigned int dccp_hdr_len(const struct sk_buff *skb)
 /* FIXME: for now we're default to 1 but it should really be 0 */
 #define DCCPF_INITIAL_SEND_NDP_COUNT		1
 
-/**
-  * struct dccp_minisock - Minimal DCCP connection representation
-  *
-  * Will be used to pass the state from dccp_request_sock to dccp_sock.
-  *
-  * @dccpms_sequence_window - Sequence Window Feature (section 7.5.2)
-  */
-struct dccp_minisock {
-	__u64			dccpms_sequence_window;
-};
-
-extern void dccp_minisock_init(struct dccp_minisock *dmsk);
-
 /**
  * struct dccp_request_sock  -  represent DCCP-specific connection request
  * @dreq_inet_rsk: structure inherited from
@@ -464,13 +451,14 @@ struct dccp_ackvec;
  * @dccps_timestamp_time - time of receiving latest @dccps_timestamp_echo
  * @dccps_l_ack_ratio - feature-local Ack Ratio
  * @dccps_r_ack_ratio - feature-remote Ack Ratio
+ * @dccps_l_seq_win - local Sequence Window (influences ack number validity)
+ * @dccps_r_seq_win - remote Sequence Window (influences seq number validity)
  * @dccps_pcslen - sender   partial checksum coverage (via sockopt)
  * @dccps_pcrlen - receiver partial checksum coverage (via sockopt)
  * @dccps_send_ndp_count - local Send NDP Count feature (7.7.2)
  * @dccps_ndp_count - number of Non Data Packets since last data packet
  * @dccps_mss_cache - current value of MSS (path MTU minus header sizes)
  * @dccps_rate_last - timestamp for rate-limiting DCCP-Sync (RFC 4340, 7.5.4)
- * @dccps_minisock - associated minisock (accessed via dccp_msk)
  * @dccps_featneg - tracks feature-negotiation state (mostly during handshake)
  * @dccps_hc_rx_ackvec - rx half connection ack vector
  * @dccps_hc_rx_ccid - CCID used for the receiver (or receiving half-connection)
@@ -504,12 +492,13 @@ struct dccp_sock {
 	__u32				dccps_timestamp_time;
 	__u16				dccps_l_ack_ratio;
 	__u16				dccps_r_ack_ratio;
+	__u64				dccps_l_seq_win:48;
+	__u64				dccps_r_seq_win:48;
 	__u8				dccps_pcslen:4;
 	__u8				dccps_pcrlen:4;
 	__u8				dccps_send_ndp_count:1;
 	__u64				dccps_ndp_count:48;
 	unsigned long			dccps_rate_last;
-	struct dccp_minisock		dccps_minisock;
 	struct list_head		dccps_featneg;
 	struct dccp_ackvec		*dccps_hc_rx_ackvec;
 	struct ccid			*dccps_hc_rx_ccid;
@@ -527,11 +516,6 @@ static inline struct dccp_sock *dccp_sk(const struct sock *sk)
 	return (struct dccp_sock *)sk;
 }
 
-static inline struct dccp_minisock *dccp_msk(const struct sock *sk)
-{
-	return (struct dccp_minisock *)&dccp_sk(sk)->dccps_minisock;
-}
-
 static inline const char *dccp_role(const struct sock *sk)
 {
 	switch (dccp_sk(sk)->dccps_role) {
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index 3fd16e82c003..6101ecdb85b6 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -409,23 +409,21 @@ static inline void dccp_hdr_set_ack(struct dccp_hdr_ack_bits *dhack,
 static inline void dccp_update_gsr(struct sock *sk, u64 seq)
 {
 	struct dccp_sock *dp = dccp_sk(sk);
-	const struct dccp_minisock *dmsk = dccp_msk(sk);
 
 	dp->dccps_gsr = seq;
-	dccp_set_seqno(&dp->dccps_swl,
-		       dp->dccps_gsr + 1 - (dmsk->dccpms_sequence_window / 4));
-	dccp_set_seqno(&dp->dccps_swh,
-		       dp->dccps_gsr + (3 * dmsk->dccpms_sequence_window) / 4);
+	/* Sequence validity window depends on remote Sequence Window (7.5.1) */
+	dp->dccps_swl = SUB48(ADD48(dp->dccps_gsr, 1), dp->dccps_r_seq_win / 4);
+	dp->dccps_swh = ADD48(dp->dccps_gsr, (3 * dp->dccps_r_seq_win) / 4);
 }
 
 static inline void dccp_update_gss(struct sock *sk, u64 seq)
 {
 	struct dccp_sock *dp = dccp_sk(sk);
 
-	dp->dccps_awh = dp->dccps_gss = seq;
-	dccp_set_seqno(&dp->dccps_awl,
-		       (dp->dccps_gss -
-			dccp_msk(sk)->dccpms_sequence_window + 1));
+	dp->dccps_gss = seq;
+	/* Ack validity window depends on local Sequence Window value (7.5.1) */
+	dp->dccps_awl = SUB48(ADD48(dp->dccps_gss, 1), dp->dccps_l_seq_win);
+	dp->dccps_awh = dp->dccps_gss;
 }
 
 static inline int dccp_ack_pending(const struct sock *sk)
diff --git a/net/dccp/feat.c b/net/dccp/feat.c
index 9a4938092783..843465999854 100644
--- a/net/dccp/feat.c
+++ b/net/dccp/feat.c
@@ -52,8 +52,17 @@ static int dccp_hdlr_ccid(struct sock *sk, u64 ccid, bool rx)
 
 static int dccp_hdlr_seq_win(struct sock *sk, u64 seq_win, bool rx)
 {
-	if (!rx)
-		dccp_msk(sk)->dccpms_sequence_window = seq_win;
+	struct dccp_sock *dp = dccp_sk(sk);
+
+	if (rx) {
+		dp->dccps_r_seq_win = seq_win;
+		/* propagate changes to update SWL/SWH */
+		dccp_update_gsr(sk, dp->dccps_gsr);
+	} else {
+		dp->dccps_l_seq_win = seq_win;
+		/* propagate changes to update AWL */
+		dccp_update_gss(sk, dp->dccps_gss);
+	}
 	return 0;
 }
 
diff --git a/net/dccp/minisocks.c b/net/dccp/minisocks.c
index 0ebf8ebcf3de..0ecb19c5e8ce 100644
--- a/net/dccp/minisocks.c
+++ b/net/dccp/minisocks.c
@@ -42,11 +42,6 @@ struct inet_timewait_death_row dccp_death_row = {
 
 EXPORT_SYMBOL_GPL(dccp_death_row);
 
-void dccp_minisock_init(struct dccp_minisock *dmsk)
-{
-	dmsk->dccpms_sequence_window = sysctl_dccp_feat_sequence_window;
-}
-
 void dccp_time_wait(struct sock *sk, int state, int timeo)
 {
 	struct inet_timewait_sock *tw = NULL;
@@ -110,7 +105,6 @@ struct sock *dccp_create_openreq_child(struct sock *sk,
 		struct dccp_request_sock *dreq = dccp_rsk(req);
 		struct inet_connection_sock *newicsk = inet_csk(newsk);
 		struct dccp_sock *newdp = dccp_sk(newsk);
-		struct dccp_minisock *newdmsk = dccp_msk(newsk);
 
 		newdp->dccps_role	    = DCCP_ROLE_SERVER;
 		newdp->dccps_hc_rx_ackvec   = NULL;
@@ -128,10 +122,6 @@ struct sock *dccp_create_openreq_child(struct sock *sk,
 		 *    Initialize S.GAR := S.ISS
 		 *    Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
 		 */
-
-		/* See dccp_v4_conn_request */
-		newdmsk->dccpms_sequence_window = req->rcv_wnd;
-
 		newdp->dccps_gar = newdp->dccps_iss = dreq->dreq_iss;
 		dccp_update_gss(newsk, dreq->dreq_iss);
 
@@ -289,7 +279,6 @@ int dccp_reqsk_init(struct request_sock *req,
 
 	inet_rsk(req)->rmt_port	  = dccp_hdr(skb)->dccph_sport;
 	inet_rsk(req)->acked	  = 0;
-	req->rcv_wnd		  = sysctl_dccp_feat_sequence_window;
 	dreq->dreq_timestamp_echo = 0;
 
 	/* inherit feature negotiation options from listening socket */
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index 775eaa3d0c49..392a5d822b33 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -180,8 +180,6 @@ int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized)
 	struct dccp_sock *dp = dccp_sk(sk);
 	struct inet_connection_sock *icsk = inet_csk(sk);
 
-	dccp_minisock_init(&dp->dccps_minisock);
-
 	icsk->icsk_rto		= DCCP_TIMEOUT_INIT;
 	icsk->icsk_syn_retries	= sysctl_dccp_request_retries;
 	sk->sk_state		= DCCP_CLOSED;
-- 
cgit v1.2.3


From d6da3511d6b558d0b017777b61dc08b8fbc06ea4 Mon Sep 17 00:00:00 2001
From: Tomasz Grobelny <tomasz@grobelny.oswiecenia.net>
Date: Thu, 4 Sep 2008 07:30:19 +0200
Subject: dccp: Policy-based packet dequeueing infrastructure

This patch adds a generic infrastructure for policy-based dequeueing of
TX packets and provides two policies:
 * a simple FIFO policy (which is the default) and
 * a priority based policy (set via socket options).
Both policies honour the tx_qlen sysctl for the maximum size of the write
queue (can be overridden via socket options).

The priority policy uses skb->priority internally to assign an u32 priority
identifier, using the same ranking as SO_PRIORITY. The skb->priority field
is set to 0 when the packet leaves DCCP. The priority is supplied as ancillary
data using cmsg(3), the patch also provides the requisite parsing routines.

Signed-off-by: Tomasz Grobelny <tomasz@grobelny.oswiecenia.net>
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
---
 Documentation/networking/dccp.txt |  19 ++++++
 include/linux/dccp.h              |  21 +++++++
 net/dccp/Makefile                 |   2 +-
 net/dccp/dccp.h                   |  12 ++++
 net/dccp/output.c                 |   7 +--
 net/dccp/proto.c                  |  67 +++++++++++++++++++-
 net/dccp/qpolicy.c                | 126 ++++++++++++++++++++++++++++++++++++++
 7 files changed, 246 insertions(+), 8 deletions(-)
 create mode 100644 net/dccp/qpolicy.c

(limited to 'Documentation')

diff --git a/Documentation/networking/dccp.txt b/Documentation/networking/dccp.txt
index b132e4a3cf0f..fcfc12534428 100644
--- a/Documentation/networking/dccp.txt
+++ b/Documentation/networking/dccp.txt
@@ -45,6 +45,25 @@ http://linux-net.osdl.org/index.php/DCCP_Testing#Experimental_DCCP_source_tree
 
 Socket options
 ==============
+DCCP_SOCKOPT_QPOLICY_ID sets the dequeuing policy for outgoing packets. It takes
+a policy ID as argument and can only be set before the connection (i.e. changes
+during an established connection are not supported). Currently, two policies are
+defined: the "simple" policy (DCCPQ_POLICY_SIMPLE), which does nothing special,
+and a priority-based variant (DCCPQ_POLICY_PRIO). The latter allows to pass an
+u32 priority value as ancillary data to sendmsg(), where higher numbers indicate
+a higher packet priority (similar to SO_PRIORITY). This ancillary data needs to
+be formatted using a cmsg(3) message header filled in as follows:
+	cmsg->cmsg_level = SOL_DCCP;
+	cmsg->cmsg_type	 = DCCP_SCM_PRIORITY;
+	cmsg->cmsg_len	 = CMSG_LEN(sizeof(uint32_t));	/* or CMSG_LEN(4) */
+
+DCCP_SOCKOPT_QPOLICY_TXQLEN sets the maximum length of the output queue. A zero
+value is always interpreted as unbounded queue length. If different from zero,
+the interpretation of this parameter depends on the current dequeuing policy
+(see above): the "simple" policy will enforce a fixed queue size by returning
+EAGAIN, whereas the "prio" policy enforces a fixed queue length by dropping the
+lowest-priority packet first. The default value for this parameter is
+initialised from /proc/sys/net/dccp/default/tx_qlen.
 
 DCCP_SOCKOPT_SERVICE sets the service. The specification mandates use of
 service codes (RFC 4340, sec. 8.1.2); if this socket option is not set,
diff --git a/include/linux/dccp.h b/include/linux/dccp.h
index eed52bcd35d0..010e2d87ed75 100644
--- a/include/linux/dccp.h
+++ b/include/linux/dccp.h
@@ -197,6 +197,21 @@ enum dccp_feature_numbers {
 	DCCPF_MAX_CCID_SPECIFIC = 255,
 };
 
+/* DCCP socket control message types for cmsg */
+enum dccp_cmsg_type {
+	DCCP_SCM_PRIORITY = 1,
+	DCCP_SCM_QPOLICY_MAX = 0xFFFF,
+	/* ^-- Up to here reserved exclusively for qpolicy parameters */
+	DCCP_SCM_MAX
+};
+
+/* DCCP priorities for outgoing/queued packets */
+enum dccp_packet_dequeueing_policy {
+	DCCPQ_POLICY_SIMPLE,
+	DCCPQ_POLICY_PRIO,
+	DCCPQ_POLICY_MAX
+};
+
 /* DCCP socket options */
 #define DCCP_SOCKOPT_PACKET_SIZE	1 /* XXX deprecated, without effect */
 #define DCCP_SOCKOPT_SERVICE		2
@@ -210,6 +225,8 @@ enum dccp_feature_numbers {
 #define DCCP_SOCKOPT_CCID		13
 #define DCCP_SOCKOPT_TX_CCID		14
 #define DCCP_SOCKOPT_RX_CCID		15
+#define DCCP_SOCKOPT_QPOLICY_ID		16
+#define DCCP_SOCKOPT_QPOLICY_TXQLEN	17
 #define DCCP_SOCKOPT_CCID_RX_INFO	128
 #define DCCP_SOCKOPT_CCID_TX_INFO	192
 
@@ -458,6 +475,8 @@ struct dccp_ackvec;
  * @dccps_hc_rx_ccid - CCID used for the receiver (or receiving half-connection)
  * @dccps_hc_tx_ccid - CCID used for the sender (or sending half-connection)
  * @dccps_options_received - parsed set of retrieved options
+ * @dccps_qpolicy - TX dequeueing policy, one of %dccp_packet_dequeueing_policy
+ * @dccps_tx_qlen - maximum length of the TX queue
  * @dccps_role - role of this sock, one of %dccp_role
  * @dccps_hc_rx_insert_options - receiver wants to add options when acking
  * @dccps_hc_tx_insert_options - sender wants to add options when sending
@@ -500,6 +519,8 @@ struct dccp_sock {
 	struct ccid			*dccps_hc_rx_ccid;
 	struct ccid			*dccps_hc_tx_ccid;
 	struct dccp_options_received	dccps_options_received;
+	__u8				dccps_qpolicy;
+	__u32				dccps_tx_qlen;
 	enum dccp_role			dccps_role:2;
 	__u8				dccps_hc_rx_insert_options:1;
 	__u8				dccps_hc_tx_insert_options:1;
diff --git a/net/dccp/Makefile b/net/dccp/Makefile
index b68440bd7fa2..0c1c9af2bf7e 100644
--- a/net/dccp/Makefile
+++ b/net/dccp/Makefile
@@ -1,7 +1,7 @@
 obj-$(CONFIG_IP_DCCP) += dccp.o dccp_ipv4.o
 
 dccp-y := ccid.o feat.o input.o minisocks.o options.o \
-	  output.o proto.o timer.o ackvec.o
+	  qpolicy.o output.o proto.o timer.o ackvec.o
 
 dccp_ipv4-y := ipv4.o
 
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index 74c90cd27677..ce2dd6f6f34d 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -234,6 +234,18 @@ extern void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
 extern void dccp_send_sync(struct sock *sk, const u64 seq,
 			   const enum dccp_pkt_type pkt_type);
 
+/*
+ * TX Packet Dequeueing Interface
+ */
+extern void		dccp_qpolicy_push(struct sock *sk, struct sk_buff *skb);
+extern bool		dccp_qpolicy_full(struct sock *sk);
+extern void		dccp_qpolicy_drop(struct sock *sk, struct sk_buff *skb);
+extern struct sk_buff	*dccp_qpolicy_top(struct sock *sk);
+extern struct sk_buff	*dccp_qpolicy_pop(struct sock *sk);
+
+/*
+ * TX Packet Output and TX Timers
+ */
 extern void dccp_write_xmit(struct sock *sk);
 extern void dccp_write_space(struct sock *sk);
 extern void dccp_flush_write_queue(struct sock *sk, long *time_budget);
diff --git a/net/dccp/output.c b/net/dccp/output.c
index b1eaf7bcfb11..2532797a8009 100644
--- a/net/dccp/output.c
+++ b/net/dccp/output.c
@@ -241,7 +241,7 @@ static void dccp_xmit_packet(struct sock *sk)
 {
 	int err, len;
 	struct dccp_sock *dp = dccp_sk(sk);
-	struct sk_buff *skb = skb_dequeue(&sk->sk_write_queue);
+	struct sk_buff *skb = dccp_qpolicy_pop(sk);
 
 	if (unlikely(skb == NULL))
 		return;
@@ -344,7 +344,7 @@ void dccp_write_xmit(struct sock *sk)
 	struct dccp_sock *dp = dccp_sk(sk);
 	struct sk_buff *skb;
 
-	while ((skb = skb_peek(&sk->sk_write_queue))) {
+	while ((skb = dccp_qpolicy_top(sk))) {
 		int rc = ccid_hc_tx_send_packet(dp->dccps_hc_tx_ccid, sk, skb);
 
 		switch (ccid_packet_dequeue_eval(rc)) {
@@ -358,8 +358,7 @@ void dccp_write_xmit(struct sock *sk)
 			dccp_xmit_packet(sk);
 			break;
 		case CCID_PACKET_ERR:
-			skb_dequeue(&sk->sk_write_queue);
-			kfree_skb(skb);
+			dccp_qpolicy_drop(sk, skb);
 			dccp_pr_debug("packet discarded due to err=%d\n", rc);
 		}
 	}
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index 8c125ffab1c5..b56efdd2a421 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -189,6 +189,7 @@ 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_tx_qlen	= sysctl_dccp_tx_qlen;
 
 	dccp_init_xmit_timers(sk);
 
@@ -541,6 +542,20 @@ static int do_dccp_setsockopt(struct sock *sk, int level, int optname,
 	case DCCP_SOCKOPT_RECV_CSCOV:
 		err = dccp_setsockopt_cscov(sk, val, true);
 		break;
+	case DCCP_SOCKOPT_QPOLICY_ID:
+		if (sk->sk_state != DCCP_CLOSED)
+			err = -EISCONN;
+		else if (val < 0 || val >= DCCPQ_POLICY_MAX)
+			err = -EINVAL;
+		else
+			dp->dccps_qpolicy = val;
+		break;
+	case DCCP_SOCKOPT_QPOLICY_TXQLEN:
+		if (val < 0)
+			err = -EINVAL;
+		else
+			dp->dccps_tx_qlen = val;
+		break;
 	default:
 		err = -ENOPROTOOPT;
 		break;
@@ -648,6 +663,12 @@ static int do_dccp_getsockopt(struct sock *sk, int level, int optname,
 	case DCCP_SOCKOPT_RECV_CSCOV:
 		val = dp->dccps_pcrlen;
 		break;
+	case DCCP_SOCKOPT_QPOLICY_ID:
+		val = dp->dccps_qpolicy;
+		break;
+	case DCCP_SOCKOPT_QPOLICY_TXQLEN:
+		val = dp->dccps_tx_qlen;
+		break;
 	case 128 ... 191:
 		return ccid_hc_rx_getsockopt(dp->dccps_hc_rx_ccid, sk, optname,
 					     len, (u32 __user *)optval, optlen);
@@ -690,6 +711,43 @@ int compat_dccp_getsockopt(struct sock *sk, int level, int optname,
 EXPORT_SYMBOL_GPL(compat_dccp_getsockopt);
 #endif
 
+static int dccp_msghdr_parse(struct msghdr *msg, struct sk_buff *skb)
+{
+	struct cmsghdr *cmsg = CMSG_FIRSTHDR(msg);
+
+	/*
+	 * Assign an (opaque) qpolicy priority value to skb->priority.
+	 *
+	 * We are overloading this skb field for use with the qpolicy subystem.
+	 * The skb->priority is normally used for the SO_PRIORITY option, which
+	 * is initialised from sk_priority. Since the assignment of sk_priority
+	 * to skb->priority happens later (on layer 3), we overload this field
+	 * for use with queueing priorities as long as the skb is on layer 4.
+	 * The default priority value (if nothing is set) is 0.
+	 */
+	skb->priority = 0;
+
+	for (; cmsg != NULL; cmsg = CMSG_NXTHDR(msg, cmsg)) {
+
+		if (!CMSG_OK(msg, cmsg))
+			return -EINVAL;
+
+		if (cmsg->cmsg_level != SOL_DCCP)
+			continue;
+
+		switch (cmsg->cmsg_type) {
+		case DCCP_SCM_PRIORITY:
+			if (cmsg->cmsg_len != CMSG_LEN(sizeof(__u32)))
+				return -EINVAL;
+			skb->priority = *(__u32 *)CMSG_DATA(cmsg);
+			break;
+		default:
+			return -EINVAL;
+		}
+	}
+	return 0;
+}
+
 int dccp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 		 size_t len)
 {
@@ -705,8 +763,7 @@ int dccp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 
 	lock_sock(sk);
 
-	if (sysctl_dccp_tx_qlen &&
-	    (sk->sk_write_queue.qlen >= sysctl_dccp_tx_qlen)) {
+	if (dccp_qpolicy_full(sk)) {
 		rc = -EAGAIN;
 		goto out_release;
 	}
@@ -734,7 +791,11 @@ int dccp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	if (rc != 0)
 		goto out_discard;
 
-	skb_queue_tail(&sk->sk_write_queue, skb);
+	rc = dccp_msghdr_parse(msg, skb);
+	if (rc != 0)
+		goto out_discard;
+
+	dccp_qpolicy_push(sk, skb);
 	dccp_write_xmit(sk);
 out_release:
 	release_sock(sk);
diff --git a/net/dccp/qpolicy.c b/net/dccp/qpolicy.c
new file mode 100644
index 000000000000..414696b0d830
--- /dev/null
+++ b/net/dccp/qpolicy.c
@@ -0,0 +1,126 @@
+/*
+ *  net/dccp/qpolicy.c
+ *
+ *  Policy-based packet dequeueing interface for DCCP.
+ *
+ *  Copyright (c) 2008 Tomasz Grobelny <tomasz@grobelny.oswiecenia.net>
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public License v2
+ *  as published by the Free Software Foundation.
+ */
+#include "dccp.h"
+
+/*
+ *	Simple Dequeueing Policy:
+ *	If tx_qlen is different from 0, enqueue up to tx_qlen elements.
+ */
+static void qpolicy_simple_push(struct sock *sk, struct sk_buff *skb)
+{
+	skb_queue_tail(&sk->sk_write_queue, skb);
+}
+
+static bool qpolicy_simple_full(struct sock *sk)
+{
+	return dccp_sk(sk)->dccps_tx_qlen &&
+	       sk->sk_write_queue.qlen >= dccp_sk(sk)->dccps_tx_qlen;
+}
+
+static struct sk_buff *qpolicy_simple_top(struct sock *sk)
+{
+	return skb_peek(&sk->sk_write_queue);
+}
+
+/*
+ *	Priority-based Dequeueing Policy:
+ *	If tx_qlen is different from 0 and the queue has reached its upper bound
+ *	of tx_qlen elements, replace older packets lowest-priority-first.
+ */
+static struct sk_buff *qpolicy_prio_best_skb(struct sock *sk)
+{
+	struct sk_buff *skb, *best = NULL;
+
+	skb_queue_walk(&sk->sk_write_queue, skb)
+		if (best == NULL || skb->priority > best->priority)
+			best = skb;
+	return best;
+}
+
+static struct sk_buff *qpolicy_prio_worst_skb(struct sock *sk)
+{
+	struct sk_buff *skb, *worst = NULL;
+
+	skb_queue_walk(&sk->sk_write_queue, skb)
+		if (worst == NULL || skb->priority < worst->priority)
+			worst = skb;
+	return worst;
+}
+
+static bool qpolicy_prio_full(struct sock *sk)
+{
+	if (qpolicy_simple_full(sk))
+		dccp_qpolicy_drop(sk, qpolicy_prio_worst_skb(sk));
+	return false;
+}
+
+/**
+ * struct dccp_qpolicy_operations  -  TX Packet Dequeueing Interface
+ * @push: add a new @skb to the write queue
+ * @full: indicates that no more packets will be admitted
+ * @top:  peeks at whatever the queueing policy defines as its `top'
+ */
+static struct dccp_qpolicy_operations {
+	void		(*push)	(struct sock *sk, struct sk_buff *skb);
+	bool		(*full) (struct sock *sk);
+	struct sk_buff*	(*top)  (struct sock *sk);
+
+} qpol_table[DCCPQ_POLICY_MAX] = {
+	[DCCPQ_POLICY_SIMPLE] = {
+		.push = qpolicy_simple_push,
+		.full = qpolicy_simple_full,
+		.top  = qpolicy_simple_top,
+	},
+	[DCCPQ_POLICY_PRIO] = {
+		.push = qpolicy_simple_push,
+		.full = qpolicy_prio_full,
+		.top  = qpolicy_prio_best_skb,
+	},
+};
+
+/*
+ *	Externally visible interface
+ */
+void dccp_qpolicy_push(struct sock *sk, struct sk_buff *skb)
+{
+	qpol_table[dccp_sk(sk)->dccps_qpolicy].push(sk, skb);
+}
+
+bool dccp_qpolicy_full(struct sock *sk)
+{
+	return qpol_table[dccp_sk(sk)->dccps_qpolicy].full(sk);
+}
+
+void dccp_qpolicy_drop(struct sock *sk, struct sk_buff *skb)
+{
+	if (skb != NULL) {
+		skb_unlink(skb, &sk->sk_write_queue);
+		kfree_skb(skb);
+	}
+}
+
+struct sk_buff *dccp_qpolicy_top(struct sock *sk)
+{
+	return qpol_table[dccp_sk(sk)->dccps_qpolicy].top(sk);
+}
+
+struct sk_buff *dccp_qpolicy_pop(struct sock *sk)
+{
+	struct sk_buff *skb = dccp_qpolicy_top(sk);
+
+	/* Clear any skb fields that we used internally */
+	skb->priority = 0;
+
+	if (skb)
+		skb_unlink(skb, &sk->sk_write_queue);
+	return skb;
+}
-- 
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