Bluetooth: l2cap: introduce l2cap_conn ref-counting

If we want to use l2cap_conn outside of l2cap_core.c, we need refcounting
for these objects. Otherwise, we cannot synchronize l2cap locks with
outside locks and end up with deadlocks.

Hence, introduce ref-counting for l2cap_conn objects. This doesn't affect
l2cap internals at all, as they use a direct synchronization.
We also keep a reference to the parent hci_conn for locking purposes as
l2cap_conn depends on this. This doesn't affect the connection itself but
only the lifetime of the (dead) object.

Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index 278830ef92cdbfc37c6178551f3f488415fac449..7b4cc5b98535c241689cc362a7823d5a8cebbae3 100644 (file)
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -583,6 +583,7 @@ struct l2cap_conn {
 
        struct list_head        chan_l;
        struct mutex            chan_lock;
+       struct kref             ref;
 };
 
 #define L2CAP_INFO_CL_MTU_REQ_SENT     0x01
@@ -813,4 +814,7 @@ void l2cap_logical_cfm(struct l2cap_chan *chan, struct hci_chan *hchan,
                       u8 status);
 void __l2cap_physical_cfm(struct l2cap_chan *chan, int result);
 
+void l2cap_conn_get(struct l2cap_conn *conn);
+void l2cap_conn_put(struct l2cap_conn *conn);
+
 #endif /* __L2CAP_H */

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index e09b89be1c4da0c33ff936e503b0082888c88547..be9ad89339cd513f1f556072044e095f332c7b78 100644 (file)
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -1486,7 +1486,8 @@ static void l2cap_conn_del(struct hci_conn *hcon, int err)
        }
 
        hcon->l2cap_data = NULL;
-       kfree(conn);
+       conn->hchan = NULL;
+       l2cap_conn_put(conn);
 }
 
 static void security_timeout(struct work_struct *work)
@@ -1520,8 +1521,10 @@ static struct l2cap_conn *l2cap_conn_add(struct hci_conn *hcon)
                return NULL;
        }
 
+       kref_init(&conn->ref);
        hcon->l2cap_data = conn;
        conn->hcon = hcon;
+       hci_conn_get(conn->hcon);
        conn->hchan = hchan;
 
        BT_DBG("hcon %p conn %p hchan %p", hcon, conn, hchan);
@@ -1558,6 +1561,26 @@ static struct l2cap_conn *l2cap_conn_add(struct hci_conn *hcon)
        return conn;
 }
 
+static void l2cap_conn_free(struct kref *ref)
+{
+       struct l2cap_conn *conn = container_of(ref, struct l2cap_conn, ref);
+
+       hci_conn_put(conn->hcon);
+       kfree(conn);
+}
+
+void l2cap_conn_get(struct l2cap_conn *conn)
+{
+       kref_get(&conn->ref);
+}
+EXPORT_SYMBOL(l2cap_conn_get);
+
+void l2cap_conn_put(struct l2cap_conn *conn)
+{
+       kref_put(&conn->ref, l2cap_conn_free);
+}
+EXPORT_SYMBOL(l2cap_conn_put);
+
 /* ---- Socket interface ---- */
 
 /* Find socket with psm and source / destination bdaddr.