Bluetooth: Introduce L2CAP_LM_FLUSHABLE to allow flushing of ACL packets.

With Bluetooth 2.1 ACL packets can be flushable or non-flushable. This changes
makes the default ACL packet non-flushable, and allows selection of flushable
packets on a per-L2CAP socket basis with L2CAP_LM_FLUSHABLE.

Note the HCI Write Automatic Flush Timeout command also needs to be issued
to set the flush timeout to non-zero.

Need to featurize this change to Bluetooth 2.1 chipsets only before pushing
upstream.

Signed-off-by: Nick Pelly <npelly@google.com>

2 files changed, 19 insertions, 5 deletions

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index c52f091ee6de..a49aa2bf97f3 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -1367,7 +1367,7 @@ void hci_send_acl(struct hci_conn *conn, struct sk_buff *skb, __u16 flags)
 
 	skb->dev = (void *) hdev;
 	bt_cb(skb)->pkt_type = HCI_ACLDATA_PKT;
-	hci_add_acl_hdr(skb, conn->handle, flags | ACL_START);
+	hci_add_acl_hdr(skb, conn->handle, flags);
 
 	if (!(list = skb_shinfo(skb)->frag_list)) {
 		/* Non fragmented */
@@ -1384,12 +1384,14 @@ void hci_send_acl(struct hci_conn *conn, struct sk_buff *skb, __u16 flags)
 		spin_lock_bh(&conn->data_q.lock);
 
 		__skb_queue_tail(&conn->data_q, skb);
+		flags &= ~ACL_PB_MASK;
+		flags |= ACL_CONT;
 		do {
 			skb = list; list = list->next;
 
 			skb->dev = (void *) hdev;
 			bt_cb(skb)->pkt_type = HCI_ACLDATA_PKT;
-			hci_add_acl_hdr(skb, conn->handle, flags | ACL_CONT);
+			hci_add_acl_hdr(skb, conn->handle, flags);
 
 			BT_DBG("%s frag %p len %d", hdev->name, skb, skb->len);
 
diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
index fadf26b4ed7c..8eed5d5abe87 100644
--- a/net/bluetooth/l2cap.c
+++ b/net/bluetooth/l2cap.c
@@ -360,7 +360,7 @@ static inline void l2cap_send_cmd(struct l2cap_conn *conn, u8 ident, u8 code, u1
 	if (!skb)
 		return;
 
-	hci_send_acl(conn->hcon, skb, 0);
+	hci_send_acl(conn->hcon, skb, ACL_START);
 }
 
 static inline void l2cap_send_sframe(struct l2cap_pinfo *pi, u16 control)
@@ -900,6 +900,7 @@ static void l2cap_sock_init(struct sock *sk, struct sock *parent)
 		pi->sec_level = l2cap_pi(parent)->sec_level;
 		pi->role_switch = l2cap_pi(parent)->role_switch;
 		pi->force_reliable = l2cap_pi(parent)->force_reliable;
+		pi->flushable = l2cap_pi(parent)->flushable;
 	} else {
 		pi->imtu = L2CAP_DEFAULT_MTU;
 		pi->omtu = 0;
@@ -915,6 +916,7 @@ static void l2cap_sock_init(struct sock *sk, struct sock *parent)
 		pi->sec_level = BT_SECURITY_LOW;
 		pi->role_switch = 0;
 		pi->force_reliable = 0;
+		pi->flushable = 0;
 	}
 
 	/* Default config options */
@@ -1433,10 +1435,16 @@ static void l2cap_drop_acked_frames(struct sock *sk)
 static inline void l2cap_do_send(struct sock *sk, struct sk_buff *skb)
 {
 	struct l2cap_pinfo *pi = l2cap_pi(sk);
+	u16 flags;
 
 	BT_DBG("sk %p, skb %p len %d", sk, skb, skb->len);
 
-	hci_send_acl(pi->conn->hcon, skb, 0);
+	if (pi->flushable)
+		flags = ACL_START_FLUSHABLE;
+	else
+		flags = ACL_START;
+
+	hci_send_acl(pi->conn->hcon, skb, flags);
 }
 
 static void l2cap_streaming_send(struct sock *sk)
@@ -2016,6 +2024,7 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname, char __us
 
 		l2cap_pi(sk)->role_switch    = (opt & L2CAP_LM_MASTER);
 		l2cap_pi(sk)->force_reliable = (opt & L2CAP_LM_RELIABLE);
+		l2cap_pi(sk)->flushable = (opt & L2CAP_LM_FLUSHABLE);
 		break;
 
 	default:
@@ -2146,6 +2155,9 @@ static int l2cap_sock_getsockopt_old(struct socket *sock, int optname, char __us
 		if (l2cap_pi(sk)->force_reliable)
 			opt |= L2CAP_LM_RELIABLE;
 
+		if (l2cap_pi(sk)->flushable)
+			opt |= L2CAP_LM_FLUSHABLE;
+
 		if (put_user(opt, (u32 __user *) optval))
 			err = -EFAULT;
 		break;
@@ -4645,7 +4657,7 @@ static int l2cap_recv_acldata(struct hci_conn *hcon, struct sk_buff *skb, u16 fl
 
 	BT_DBG("conn %p len %d flags 0x%x", conn, skb->len, flags);
 
-	if (flags & ACL_START) {
+	if (!(flags & ACL_CONT)) {
 		struct l2cap_hdr *hdr;
 		int len;