From fc225c3f5d1b6aa6f99c5c300af4605e4923ce79 Mon Sep 17 00:00:00 2001 From: David Herrmann Date: Sat, 6 Apr 2013 20:28:38 +0200 Subject: Bluetooth: remove unneeded hci_conn_hold/put_device() hci_conn_hold/put_device() is used to control when hci_conn->dev is no longer needed and can be deleted from the system. Lets first look how they are currently used throughout the code (excluding HIDP!). All code that uses hci_conn_hold_device() looks like this: ... hci_conn_hold_device(); hci_conn_add_sysfs(); ... On the other side, hci_conn_put_device() is exclusively used in hci_conn_del(). So, considering that hci_conn_del() must not be called twice (which would fail horribly), we know that hci_conn_put_device() is only called _once_ (which is in hci_conn_del()). On the other hand, hci_conn_add_sysfs() must not be called twice, either (it would call device_add twice, which breaks the device, see drivers/base/core.c). So we know that hci_conn_hold_device() is also called only once (it's only called directly before hci_conn_add_sysfs()). So hold and put are known to be called only once. That means we can safely remove them and directly call hci_conn_del_sysfs() in hci_conn_del(). But there is one issue left: HIDP also uses hci_conn_hold/put_device(). However, this case can be ignored and simply removed as it is totally broken. The issue is, the only thing HIDP delays with hci_conn_hold_device() is the removal of the hci_conn->dev from sysfs. But, the hci_conn device has no mechanism to get notified when its own parent (hci_dev) gets removed from sysfs. hci_dev_hold/put() does _not_ control when it is removed but only when the device object is created and destroyed. And hci_dev calls hci_conn_flush_*() when it removes itself from sysfs, which itself causes hci_conn_del() to be called, but it does _not_ cause hci_conn_del_sysfs() to be called, which is wrong. Hence, we fix it to call hci_conn_del_sysfs() in hci_conn_del(). This guarantees that a hci_conn object is removed from sysfs _before_ its parent hci_dev is removed. The changes to HIDP look scary, wrong and broken. However, if you look at the HIDP session management, you will notice they're already broken in the exact _same_ way (ever tried "unplugging" HIDP devices? Breaks _all_ the time). So this patch only makes HIDP look _scary_ and _obviously broken_. It does not break HIDP itself, it already is! See later patches in this series which fix HIDP to use proper session-management. Signed-off-by: David Herrmann Acked-by: Marcel Holtmann Signed-off-by: Gustavo Padovan --- net/bluetooth/hci_event.c | 4 ---- 1 file changed, 4 deletions(-) (limited to 'net/bluetooth/hci_event.c') diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c index f6ea3c734269..688c1a9949cc 100644 --- a/net/bluetooth/hci_event.c +++ b/net/bluetooth/hci_event.c @@ -1706,7 +1706,6 @@ static void hci_conn_complete_evt(struct hci_dev *hdev, struct sk_buff *skb) } else conn->state = BT_CONNECTED; - hci_conn_hold_device(conn); hci_conn_add_sysfs(conn); if (test_bit(HCI_AUTH, &hdev->flags)) @@ -2987,7 +2986,6 @@ static void hci_sync_conn_complete_evt(struct hci_dev *hdev, conn->handle = __le16_to_cpu(ev->handle); conn->state = BT_CONNECTED; - hci_conn_hold_device(conn); hci_conn_add_sysfs(conn); break; @@ -3452,7 +3450,6 @@ static void hci_phy_link_complete_evt(struct hci_dev *hdev, hcon->disc_timeout = HCI_DISCONN_TIMEOUT; hci_conn_drop(hcon); - hci_conn_hold_device(hcon); hci_conn_add_sysfs(hcon); amp_physical_cfm(bredr_hcon, hcon); @@ -3586,7 +3583,6 @@ static void hci_le_conn_complete_evt(struct hci_dev *hdev, struct sk_buff *skb) conn->handle = __le16_to_cpu(ev->handle); conn->state = BT_CONNECTED; - hci_conn_hold_device(conn); hci_conn_add_sysfs(conn); hci_proto_connect_cfm(conn, ev->status); -- cgit v1.2.2