Bluetooth: Move L2CAP fixed channel creation into l2cap_conn_cfm

In order to remove special handling of fixed L2CAP channels we need to
start creating them in a single place instead of having per-channel
exceptions. The most natural place is the l2cap_conn_cfm() function
which is called whenever there is a new baseband link.

The only really special case so far has been the ATT socket, so in order
not to break the code in between this patch removes the ATT special
handling at the same time as it adds the generic fixed channel handling
from l2cap_le_conn_ready() into the hci_conn_cfm() function. As a
related change the channel locking in l2cap_conn_ready() becomes simpler
and we can thereby move the smp_conn_security() call into the
l2cap_le_conn_ready() function.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/l2cap_core.c

@@ -1469,26 +1469,14 @@ static void l2cap_le_conn_ready(struct l2cap_conn *conn)
 {
 	struct hci_conn *hcon = conn->hcon;
 	struct hci_dev *hdev = hcon->hdev;
-	struct l2cap_chan *chan, *pchan;
-	u8 dst_type;
 
-	BT_DBG("");
-
-	/* Check if we have socket listening on cid */
-	pchan = l2cap_global_chan_by_scid(BT_LISTEN, L2CAP_CID_ATT,
-					  &hcon->src, &hcon->dst);
-	if (!pchan)
-		return;
+	BT_DBG("%s conn %p", hdev->name, conn);
 
-	/* Client ATT sockets should override the server one */
-	if (__l2cap_get_chan_by_dcid(conn, L2CAP_CID_ATT))
-		goto put;
-
-	dst_type = bdaddr_type(hcon, hcon->dst_type);
-
-	/* If device is blocked, do not create a channel for it */
-	if (hci_bdaddr_list_lookup(&hdev->blacklist, &hcon->dst, dst_type))
-		goto put;
+	/* For outgoing pairing which doesn't necessarily have an
+	 * associated socket (e.g. mgmt_pair_device).
+	 */
+	if (hcon->out)
+		smp_conn_security(hcon, hcon->pending_sec_level);
 
 	/* For LE slave connections, make sure the connection interval
 	 * is in the range of the minium and maximum interval that has
@@ -1508,24 +1496,6 @@ static void l2cap_le_conn_ready(struct l2cap_conn *conn)
 		l2cap_send_cmd(conn, l2cap_get_ident(conn),
 			       L2CAP_CONN_PARAM_UPDATE_REQ, sizeof(req), &req);
 	}
-
-	l2cap_chan_lock(pchan);
-
-	chan = pchan->ops->new_connection(pchan);
-	if (!chan)
-		goto clean;
-
-	bacpy(&chan->src, &hcon->src);
-	bacpy(&chan->dst, &hcon->dst);
-	chan->src_type = bdaddr_type(hcon, hcon->src_type);
-	chan->dst_type = dst_type;
-
-	__l2cap_chan_add(conn, chan);
-
-clean:
-	l2cap_chan_unlock(pchan);
-put:
-	l2cap_chan_put(pchan);
 }
 
 static void l2cap_conn_ready(struct l2cap_conn *conn)
@@ -1535,17 +1505,11 @@ static void l2cap_conn_ready(struct l2cap_conn *conn)
 
 	BT_DBG("conn %p", conn);
 
-	/* For outgoing pairing which doesn't necessarily have an
-	 * associated socket (e.g. mgmt_pair_device).
-	 */
-	if (hcon->out && hcon->type == LE_LINK)
-		smp_conn_security(hcon, hcon->pending_sec_level);
-
-	mutex_lock(&conn->chan_lock);
-
 	if (hcon->type == LE_LINK)
 		l2cap_le_conn_ready(conn);
 
+	mutex_lock(&conn->chan_lock);
+
 	list_for_each_entry(chan, &conn->chan_l, list) {
 
 		l2cap_chan_lock(chan);
@@ -7262,9 +7226,44 @@ int l2cap_connect_ind(struct hci_dev *hdev, bdaddr_t *bdaddr)
 	return exact ? lm1 : lm2;
 }
 
+/* Find the next fixed channel in BT_LISTEN state, continue iteration
+ * from an existing channel in the list or from the beginning of the
+ * global list (by passing NULL as first parameter).
+ */
+static struct l2cap_chan *l2cap_global_fixed_chan(struct l2cap_chan *c,
+						  bdaddr_t *src)
+{
+	read_lock(&chan_list_lock);
+
+	if (c)
+		c = list_next_entry(c, global_l);
+	else
+		c = list_entry(chan_list.next, typeof(*c), global_l);
+
+	list_for_each_entry_from(c, &chan_list, global_l) {
+		if (c->chan_type != L2CAP_CHAN_FIXED)
+			continue;
+		if (c->state != BT_LISTEN)
+			continue;
+		if (bacmp(&c->src, src) && bacmp(&c->src, BDADDR_ANY))
+			continue;
+
+		l2cap_chan_hold(c);
+		read_unlock(&chan_list_lock);
+		return c;
+	}
+
+	read_unlock(&chan_list_lock);
+
+	return NULL;
+}
+
 void l2cap_connect_cfm(struct hci_conn *hcon, u8 status)
 {
+	struct hci_dev *hdev = hcon->hdev;
 	struct l2cap_conn *conn;
+	struct l2cap_chan *pchan;
+	u8 dst_type;
 
 	BT_DBG("hcon %p bdaddr %pMR status %d", hcon, &hcon->dst, status);
 
@@ -7277,6 +7276,43 @@ void l2cap_connect_cfm(struct hci_conn *hcon, u8 status)
 	if (!conn)
 		return;
 
+	dst_type = bdaddr_type(hcon, hcon->dst_type);
+
+	/* If device is blocked, do not create channels for it */
+	if (hci_bdaddr_list_lookup(&hdev->blacklist, &hcon->dst, dst_type))
+		return;
+
+	/* Find fixed channels and notify them of the new connection. We
+	 * use multiple individual lookups, continuing each time where
+	 * we left off, because the list lock would prevent calling the
+	 * potentially sleeping l2cap_chan_lock() function.
+	 */
+	pchan = l2cap_global_fixed_chan(NULL, &hdev->bdaddr);
+	while (pchan) {
+		struct l2cap_chan *chan, *next;
+
+		/* Client fixed channels should override server ones */
+		if (__l2cap_get_chan_by_dcid(conn, pchan->scid))
+			goto next;
+
+		l2cap_chan_lock(pchan);
+		chan = pchan->ops->new_connection(pchan);
+		if (chan) {
+			bacpy(&chan->src, &hcon->src);
+			bacpy(&chan->dst, &hcon->dst);
+			chan->src_type = bdaddr_type(hcon, hcon->src_type);
+			chan->dst_type = dst_type;
+
+			__l2cap_chan_add(conn, chan);
+		}
+
+		l2cap_chan_unlock(pchan);
+next:
+		next = l2cap_global_fixed_chan(pchan, &hdev->bdaddr);
+		l2cap_chan_put(pchan);
+		pchan = next;
+	}
+
 	l2cap_conn_ready(conn);
 }