Bluetooth: Add extra device reference counting for connections
The device model itself has no real usable reference counting at the
moment and this causes problems if parents are deleted before their
children. The device model itself handles the memory details of this
correctly, but the uevent order is not consistent. This causes various
problems for systems like HAL or even X.
So until device_put() does a proper cleanup, the device for Bluetooth
connection will be protected with an extra reference counting to ensure
the correct order of uevents when connections are terminated.
This is not an automatic feature. Higher Bluetooth layers like HIDP or
BNEP should grab this new reference to ensure that their uevents are
send before the ones from the parent device.
Based on a report by Brian Rogers <brian@xyzw.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
index c4ca422..25b8a03 100644
--- a/include/net/bluetooth/hci_core.h
+++ b/include/net/bluetooth/hci_core.h
@@ -187,6 +187,7 @@
struct work_struct work_del;
struct device dev;
+ atomic_t devref;
struct hci_dev *hdev;
void *l2cap_data;
@@ -339,6 +340,9 @@
void hci_conn_enter_active_mode(struct hci_conn *conn);
void hci_conn_enter_sniff_mode(struct hci_conn *conn);
+void hci_conn_hold_device(struct hci_conn *conn);
+void hci_conn_put_device(struct hci_conn *conn);
+
static inline void hci_conn_hold(struct hci_conn *conn)
{
atomic_inc(&conn->refcnt);
diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index fa47d5d..a975098 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -246,6 +246,8 @@
if (hdev->notify)
hdev->notify(hdev, HCI_NOTIFY_CONN_ADD);
+ atomic_set(&conn->devref, 0);
+
hci_conn_init_sysfs(conn);
tasklet_enable(&hdev->tx_task);
@@ -288,7 +290,7 @@
skb_queue_purge(&conn->data_q);
- hci_conn_del_sysfs(conn);
+ hci_conn_put_device(conn);
hci_dev_put(hdev);
@@ -583,6 +585,19 @@
hci_dev_unlock(hdev);
}
+void hci_conn_hold_device(struct hci_conn *conn)
+{
+ atomic_inc(&conn->devref);
+}
+EXPORT_SYMBOL(hci_conn_hold_device);
+
+void hci_conn_put_device(struct hci_conn *conn)
+{
+ if (atomic_dec_and_test(&conn->devref))
+ hci_conn_del_sysfs(conn);
+}
+EXPORT_SYMBOL(hci_conn_put_device);
+
int hci_get_conn_list(void __user *arg)
{
struct hci_conn_list_req req, *cl;
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
index 184ba0a..e99fe38 100644
--- a/net/bluetooth/hci_event.c
+++ b/net/bluetooth/hci_event.c
@@ -887,6 +887,7 @@
} else
conn->state = BT_CONNECTED;
+ hci_conn_hold_device(conn);
hci_conn_add_sysfs(conn);
if (test_bit(HCI_AUTH, &hdev->flags))
@@ -1693,6 +1694,7 @@
conn->handle = __le16_to_cpu(ev->handle);
conn->state = BT_CONNECTED;
+ hci_conn_hold_device(conn);
hci_conn_add_sysfs(conn);
break;