Bluetooth: Enable Streaming Mode for L2CAP

Streaming Mode is helpful for the Bluetooth streaming based profiles, such
as A2DP. It doesn't have any error control or flow control.

Signed-off-by: Gustavo F. Padovan <gustavo@las.ic.unicamp.br>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

1 files changed, 73 insertions, 9 deletions

diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
index 97172f7c0a6a..7f835e761822 100644
--- a/net/bluetooth/l2cap.c
+++ b/net/bluetooth/l2cap.c
@@ -1245,6 +1245,39 @@ static inline int l2cap_do_send(struct sock *sk, struct sk_buff *skb)
         return err;
 }
 
+static int l2cap_streaming_send(struct sock *sk)
+{
+        struct sk_buff *skb, *tx_skb;
+        struct l2cap_pinfo *pi = l2cap_pi(sk);
+        u16 control;
+        int err;
+
+        while ((skb = sk->sk_send_head)) {
+                tx_skb = skb_clone(skb, GFP_ATOMIC);
+
+                control = get_unaligned_le16(tx_skb->data + L2CAP_HDR_SIZE);
+                control |= pi->next_tx_seq << L2CAP_CTRL_TXSEQ_SHIFT;
+                put_unaligned_le16(control, tx_skb->data + L2CAP_HDR_SIZE);
+
+                err = l2cap_do_send(sk, tx_skb);
+                if (err < 0) {
+                        l2cap_send_disconn_req(pi->conn, sk);
+                        return err;
+                }
+
+                pi->next_tx_seq = (pi->next_tx_seq + 1) % 64;
+
+                if (skb_queue_is_last(TX_QUEUE(sk), skb))
+                        sk->sk_send_head = NULL;
+                else
+                        sk->sk_send_head = skb_queue_next(TX_QUEUE(sk), skb);
+
+                skb = skb_dequeue(TX_QUEUE(sk));
+                kfree_skb(skb);
+        }
+        return 0;
+}
+
 static int l2cap_ertm_send(struct sock *sk)
 {
         struct sk_buff *skb, *tx_skb;
@@ -1383,7 +1416,7 @@ static struct sk_buff *l2cap_create_basic_pdu(struct sock *sk, struct msghdr *ms
         return skb;
 }
 
-static struct sk_buff *l2cap_create_ertm_pdu(struct sock *sk, struct msghdr *msg, size_t len, u16 control, u16 sdulen)
+static struct sk_buff *l2cap_create_iframe_pdu(struct sock *sk, struct msghdr *msg, size_t len, u16 control, u16 sdulen)
 {
         struct l2cap_conn *conn = l2cap_pi(sk)->conn;
         struct sk_buff *skb;
@@ -1429,7 +1462,7 @@ static inline int l2cap_sar_segment_sdu(struct sock *sk, struct msghdr *msg, siz
 
         __skb_queue_head_init(&sar_queue);
         control = L2CAP_SDU_START;
-        skb = l2cap_create_ertm_pdu(sk, msg, pi->max_pdu_size, control, len);
+        skb = l2cap_create_iframe_pdu(sk, msg, pi->max_pdu_size, control, len);
         if (IS_ERR(skb))
                 return PTR_ERR(skb);
 
@@ -1449,7 +1482,7 @@ static inline int l2cap_sar_segment_sdu(struct sock *sk, struct msghdr *msg, siz
                         buflen = len;
                 }
 
-                skb = l2cap_create_ertm_pdu(sk, msg, buflen, control, 0);
+                skb = l2cap_create_iframe_pdu(sk, msg, buflen, control, 0);
                 if (IS_ERR(skb)) {
                         skb_queue_purge(&sar_queue);
                         return PTR_ERR(skb);
@@ -1518,10 +1551,11 @@ static int l2cap_sock_sendmsg(struct kiocb *iocb, struct socket *sock, struct ms
                 break;
 
         case L2CAP_MODE_ERTM:
+        case L2CAP_MODE_STREAMING:
                 /* Entire SDU fits into one PDU */
                 if (len <= pi->max_pdu_size) {
                         control = L2CAP_SDU_UNSEGMENTED;
-                        skb = l2cap_create_ertm_pdu(sk, msg, len, control, 0);
+                        skb = l2cap_create_iframe_pdu(sk, msg, len, control, 0);
                         if (IS_ERR(skb)) {
                                 err = PTR_ERR(skb);
                                 goto done;
@@ -1536,7 +1570,11 @@ static int l2cap_sock_sendmsg(struct kiocb *iocb, struct socket *sock, struct ms
                                 goto done;
                 }
 
-                err = l2cap_ertm_send(sk);
+                if (pi->mode == L2CAP_MODE_STREAMING)
+                        err = l2cap_streaming_send(sk);
+                else
+                        err = l2cap_ertm_send(sk);
+
                 if (!err)
                         err = len;
                 break;
@@ -2050,7 +2088,7 @@ static int l2cap_mode_supported(__u8 mode, __u32 feat_mask)
 {
         u32 local_feat_mask = l2cap_feat_mask;
         if (enable_ertm)
-                local_feat_mask |= L2CAP_FEAT_ERTM;
+                local_feat_mask |= L2CAP_FEAT_ERTM | L2CAP_FEAT_STREAMING;
 
         switch (mode) {
         case L2CAP_MODE_ERTM:
@@ -2771,7 +2809,7 @@ static inline int l2cap_information_req(struct l2cap_conn *conn, struct l2cap_cm
                 rsp->type   = cpu_to_le16(L2CAP_IT_FEAT_MASK);
                 rsp->result = cpu_to_le16(L2CAP_IR_SUCCESS);
                 if (enable_ertm)
-                        feat_mask |= L2CAP_FEAT_ERTM;
+                        feat_mask |= L2CAP_FEAT_ERTM | L2CAP_FEAT_STREAMING;
                 put_unaligned(cpu_to_le32(feat_mask), (__le32 *) rsp->data);
                 l2cap_send_cmd(conn, cmd->ident,
                                         L2CAP_INFO_RSP, sizeof(buf), buf);
@@ -3096,7 +3134,9 @@ static inline int l2cap_data_channel_sframe(struct sock *sk, u16 rx_control, str
 static inline int l2cap_data_channel(struct l2cap_conn *conn, u16 cid, struct sk_buff *skb)
 {
         struct sock *sk;
+        struct l2cap_pinfo *pi;
         u16 control, len;
+        u8 tx_seq;
         int err;
 
         sk = l2cap_get_chan_by_scid(&conn->chan_list, cid);
@@ -3105,19 +3145,21 @@ static inline int l2cap_data_channel(struct l2cap_conn *conn, u16 cid, struct sk
                 goto drop;
         }
 
+        pi = l2cap_pi(sk);
+
         BT_DBG("sk %p, len %d", sk, skb->len);
 
         if (sk->sk_state != BT_CONNECTED)
                 goto drop;
 
-        switch (l2cap_pi(sk)->mode) {
+        switch (pi->mode) {
         case L2CAP_MODE_BASIC:
                 /* If socket recv buffers overflows we drop data here
                  * which is *bad* because L2CAP has to be reliable.
                  * But we don't have any other choice. L2CAP doesn't
                  * provide flow control mechanism. */
 
-                if (l2cap_pi(sk)->imtu < skb->len)
+                if (pi->imtu < skb->len)
                         goto drop;
 
                 if (!sock_queue_rcv_skb(sk, skb))
@@ -3149,6 +3191,28 @@ static inline int l2cap_data_channel(struct l2cap_conn *conn, u16 cid, struct sk
                         goto done;
                 break;
 
+        case L2CAP_MODE_STREAMING:
+                control = get_unaligned_le16(skb->data);
+                skb_pull(skb, 2);
+                len = skb->len;
+
+                if (__is_sar_start(control))
+                        len -= 2;
+
+                if (len > L2CAP_DEFAULT_MAX_PDU_SIZE || __is_sframe(control))
+                        goto drop;
+
+                tx_seq = __get_txseq(control);
+
+                if (pi->expected_tx_seq == tx_seq)
+                        pi->expected_tx_seq = (pi->expected_tx_seq + 1) % 64;
+                else
+                        pi->expected_tx_seq = tx_seq + 1;
+
+                err = l2cap_sar_reassembly_sdu(sk, skb, control);
+
+                goto done;
+
         default:
                 BT_DBG("sk %p: bad mode 0x%2.2x", sk, l2cap_pi(sk)->mode);
                 break;