Bluetooth: EWS: extended window size option support

Adds support for extended window size (EWS) config option. We enable EWS
feature in L2CAP Info RSP when hs enabled. EWS option is included in L2CAP
Config Req if tx_win (which is set via socket) bigger then standard default
value (63) && hs enabled && remote side supports EWS feature.

Using EWS selects extended control field in L2CAP.

Code partly based on Qualcomm and Atheros patches sent upstream a year ago.

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

include/net/bluetooth/l2cap.h

@@ -32,6 +32,7 @@
 #define L2CAP_DEFAULT_MIN_MTU		48
 #define L2CAP_DEFAULT_FLUSH_TO		0xffff
 #define L2CAP_DEFAULT_TX_WINDOW		63
+#define L2CAP_DEFAULT_EXT_WINDOW	0x3FFF
 #define L2CAP_DEFAULT_MAX_TX		3
 #define L2CAP_DEFAULT_RETRANS_TO	2000    /* 2 seconds */
 #define L2CAP_DEFAULT_MONITOR_TO	12000   /* 12 seconds */
@@ -233,6 +234,7 @@ struct l2cap_conf_opt {
 #define L2CAP_CONF_QOS		0x03
 #define L2CAP_CONF_RFC		0x04
 #define L2CAP_CONF_FCS		0x05
+#define L2CAP_CONF_EWS		0x07
 
 #define L2CAP_CONF_MAX_SIZE	22
 
@@ -333,7 +335,7 @@ struct l2cap_chan {
 
 	__u8		fcs;
 
-	__u8		tx_win;
+	__u16		tx_win;
 	__u8		max_tx;
 	__u16		retrans_timeout;
 	__u16		monitor_timeout;
@@ -357,7 +359,7 @@ struct l2cap_chan {
 	struct sk_buff	*sdu;
 	struct sk_buff	*sdu_last_frag;
 
-	__u8		remote_tx_win;
+	__u16		remote_tx_win;
 	__u8		remote_max_tx;
 	__u16		remote_mps;
 
@@ -442,6 +444,7 @@ enum {
 	CONF_CONNECT_PEND,
 	CONF_NO_FCS_RECV,
 	CONF_STATE2_DEVICE,
+	CONF_EWS_RECV,
 };
 
 #define L2CAP_CONF_MAX_CONF_REQ 2
@@ -465,6 +468,7 @@ enum {
 	FLAG_FORCE_ACTIVE,
 	FLAG_FORCE_RELIABLE,
 	FLAG_FLUSHABLE,
+	FLAG_EXT_CTRL,
 };
 
 #define __set_chan_timer(c, t) l2cap_set_timer(c, &c->chan_timer, (t))

net/bluetooth/l2cap_core.c

@@ -1898,6 +1898,22 @@ static inline __u8 l2cap_select_mode(__u8 mode, __u16 remote_feat_mask)
 	}
 }
 
+static inline bool __l2cap_ews_supported(struct l2cap_chan *chan)
+{
+	return enable_hs && chan->conn->feat_mask & L2CAP_FEAT_EXT_WINDOW;
+}
+
+static inline void l2cap_txwin_setup(struct l2cap_chan *chan)
+{
+	if (chan->tx_win > L2CAP_DEFAULT_TX_WINDOW &&
+						__l2cap_ews_supported(chan))
+		/* use extended control field */
+		set_bit(FLAG_EXT_CTRL, &chan->flags);
+	else
+		chan->tx_win = min_t(u16, chan->tx_win,
+						L2CAP_DEFAULT_TX_WINDOW);
+}
+
 static int l2cap_build_conf_req(struct l2cap_chan *chan, void *data)
 {
 	struct l2cap_conf_req *req = data;
@@ -1944,7 +1960,6 @@ done:
 
 	case L2CAP_MODE_ERTM:
 		rfc.mode            = L2CAP_MODE_ERTM;
-		rfc.txwin_size      = chan->tx_win;
 		rfc.max_transmit    = chan->max_tx;
 		rfc.retrans_timeout = 0;
 		rfc.monitor_timeout = 0;
@@ -1952,6 +1967,11 @@ done:
 		if (L2CAP_DEFAULT_MAX_PDU_SIZE > chan->conn->mtu - 10)
 			rfc.max_pdu_size = cpu_to_le16(chan->conn->mtu - 10);
 
+		l2cap_txwin_setup(chan);
+
+		rfc.txwin_size = min_t(u16, chan->tx_win,
+						L2CAP_DEFAULT_TX_WINDOW);
+
 		l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC, sizeof(rfc),
 							(unsigned long) &rfc);
 
@@ -1963,6 +1983,10 @@ done:
 			chan->fcs = L2CAP_FCS_NONE;
 			l2cap_add_conf_opt(&ptr, L2CAP_CONF_FCS, 1, chan->fcs);
 		}
+
+		if (test_bit(FLAG_EXT_CTRL, &chan->flags))
+			l2cap_add_conf_opt(&ptr, L2CAP_CONF_EWS, 2,
+								chan->tx_win);
 		break;
 
 	case L2CAP_MODE_STREAMING:
@@ -2038,6 +2062,15 @@ static int l2cap_parse_conf_req(struct l2cap_chan *chan, void *data)
 
 			break;
 
+		case L2CAP_CONF_EWS:
+			if (!enable_hs)
+				return -ECONNREFUSED;
+
+			set_bit(FLAG_EXT_CTRL, &chan->flags);
+			set_bit(CONF_EWS_RECV, &chan->conf_state);
+			chan->remote_tx_win = val;
+			break;
+
 		default:
 			if (hint)
 				break;
@@ -2098,7 +2131,11 @@ done:
 			break;
 
 		case L2CAP_MODE_ERTM:
-			chan->remote_tx_win = rfc.txwin_size;
+			if (!test_bit(CONF_EWS_RECV, &chan->conf_state))
+				chan->remote_tx_win = rfc.txwin_size;
+			else
+				rfc.txwin_size = L2CAP_DEFAULT_TX_WINDOW;
+
 			chan->remote_max_tx = rfc.max_transmit;
 
 			if (le16_to_cpu(rfc.max_pdu_size) > chan->conn->mtu - 10)
@@ -2190,6 +2227,13 @@ static int l2cap_parse_conf_rsp(struct l2cap_chan *chan, void *rsp, int len, voi
 			l2cap_add_conf_opt(&ptr, L2CAP_CONF_RFC,
 					sizeof(rfc), (unsigned long) &rfc);
 			break;
+
+		case L2CAP_CONF_EWS:
+			chan->tx_win = min_t(u16, val,
+						L2CAP_DEFAULT_EXT_WINDOW);
+			l2cap_add_conf_opt(&ptr, L2CAP_CONF_EWS,
+							2, chan->tx_win);
+			break;
 		}
 	}
 
@@ -2785,7 +2829,8 @@ static inline int l2cap_information_req(struct l2cap_conn *conn, struct l2cap_cm
 			feat_mask |= L2CAP_FEAT_ERTM | L2CAP_FEAT_STREAMING
 							 | L2CAP_FEAT_FCS;
 		if (enable_hs)
-			feat_mask |= L2CAP_FEAT_EXT_FLOW;
+			feat_mask |= L2CAP_FEAT_EXT_FLOW
+						| L2CAP_FEAT_EXT_WINDOW;
 
 		put_unaligned_le32(feat_mask, rsp->data);
 		l2cap_send_cmd(conn, cmd->ident,

net/bluetooth/l2cap_sock.c

@@ -331,7 +331,7 @@ static int l2cap_sock_getsockopt_old(struct socket *sock, int optname, char __us
 		opts.mode     = chan->mode;
 		opts.fcs      = chan->fcs;
 		opts.max_tx   = chan->max_tx;
-		opts.txwin_size = (__u16)chan->tx_win;
+		opts.txwin_size = chan->tx_win;
 
 		len = min_t(unsigned int, len, sizeof(opts));
 		if (copy_to_user(optval, (char *) &opts, len))
@@ -501,7 +501,7 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname, char __us
 		opts.mode     = chan->mode;
 		opts.fcs      = chan->fcs;
 		opts.max_tx   = chan->max_tx;
-		opts.txwin_size = (__u16)chan->tx_win;
+		opts.txwin_size = chan->tx_win;
 
 		len = min_t(unsigned int, sizeof(opts), optlen);
 		if (copy_from_user((char *) &opts, optval, len)) {
@@ -509,7 +509,7 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname, char __us
 			break;
 		}
 
-		if (opts.txwin_size > L2CAP_DEFAULT_TX_WINDOW) {
+		if (opts.txwin_size > L2CAP_DEFAULT_EXT_WINDOW) {
 			err = -EINVAL;
 			break;
 		}
@@ -533,7 +533,7 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname, char __us
 		chan->omtu = opts.omtu;
 		chan->fcs  = opts.fcs;
 		chan->max_tx = opts.max_tx;
-		chan->tx_win = (__u8)opts.txwin_size;
+		chan->tx_win = opts.txwin_size;
 		break;
 
 	case L2CAP_LM: