Bluetooth: SCO: Replace use of memcpy_from_msg with bt_skb_sendmsg

This makes use of bt_skb_sendmsg instead of allocating a different
buffer to be used with memcpy_from_msg which cause one extra copy.
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/sco.c

@@ -281,27 +281,19 @@ static int sco_connect(struct hci_dev *hdev, struct sock *sk)
 	return err;
 }
 
-static int sco_send_frame(struct sock *sk, void *buf, int len,
-			  unsigned int msg_flags)
+static int sco_send_frame(struct sock *sk, struct sk_buff *skb)
 {
 	struct sco_conn *conn = sco_pi(sk)->conn;
-	struct sk_buff *skb;
-	int err;
 
 	/* Check outgoing MTU */
-	if (len > conn->mtu)
+	if (skb->len > conn->mtu)
 		return -EINVAL;
 
-	BT_DBG("sk %p len %d", sk, len);
+	BT_DBG("sk %p len %d", sk, skb->len);
 
-	skb = bt_skb_send_alloc(sk, len, msg_flags & MSG_DONTWAIT, &err);
-	if (!skb)
-		return err;
-
-	memcpy(skb_put(skb, len), buf, len);
 	hci_send_sco(conn->hcon, skb);
 
-	return len;
+	return skb->len;
 }
 
 static void sco_recv_frame(struct sco_conn *conn, struct sk_buff *skb)
@@ -728,7 +720,7 @@ static int sco_sock_sendmsg(struct socket *sock, struct msghdr *msg,
 			    size_t len)
 {
 	struct sock *sk = sock->sk;
-	void *buf;
+	struct sk_buff *skb;
 	int err;
 
 	BT_DBG("sock %p, sk %p", sock, sk);
@@ -740,24 +732,20 @@ static int sco_sock_sendmsg(struct socket *sock, struct msghdr *msg,
 	if (msg->msg_flags & MSG_OOB)
 		return -EOPNOTSUPP;
 
-	buf = kmalloc(len, GFP_KERNEL);
-	if (!buf)
-		return -ENOMEM;
-
-	if (memcpy_from_msg(buf, msg, len)) {
-		kfree(buf);
-		return -EFAULT;
-	}
+	skb = bt_skb_sendmsg(sk, msg, len, len, 0, 0);
+	if (IS_ERR_OR_NULL(skb))
+		return PTR_ERR(skb);
 
 	lock_sock(sk);
 
 	if (sk->sk_state == BT_CONNECTED)
-		err = sco_send_frame(sk, buf, len, msg->msg_flags);
+		err = sco_send_frame(sk, skb);
 	else
 		err = -ENOTCONN;
 
 	release_sock(sk);
-	kfree(buf);
+	if (err)
+		kfree_skb(skb);
 	return err;
 }