Hi all, On Mon, Apr 2, 2012 at 7:16 AM, Alexander Holler <holler@xxxxxxxxxxxxx> wrote: > Am 02.04.2012 11:17, schrieb Alexander Holler: > >> Am 02.04.2012 11:03, schrieb Andrei Emeltchenko: >>> >>> Hi guys, >>> >>> On Mon, Apr 02, 2012 at 10:44:43AM +0200, David Herrmann wrote: >>>> >>>> Hi Andrei and Alexander >>>> >>>> On Mon, Apr 2, 2012 at 10:29 AM, Alexander Holler<holler@xxxxxxxxxxxxx> >>>> wrote: >>>>> >>>>> Am 02.04.2012 08:55, schrieb Andrei Emeltchenko: >>>>>> >>>>>> Hi Alexander, >>>>>> >>>>>> On Sat, Mar 31, 2012 at 03:23:38PM +0200, Alexander Holler wrote: >>>>>>> >>>>>>> I've experienced a deadlock on shutdown using kernel 3.3 and tracked >>>>>>> it down. Because I'm not very familiar with the bluetooth stack I'm >>>>>>> not sure if the below patch is correct, but it fixed the problem >>>>>>> here. >>>>>> >>>>>> >>>>>> Could you please attach deadlock dump? >>>>>> >>>>>>> >>>>>>> Commit 09fd0de5bd8f8ef3317e5365f92f1a13dcd89aa9 introduced a >>>>>>> deadlock: >>>>>>> >>>>>>> bluetoothd calls ioctl HCIDEVDOWN >>>>>>> hci_sock_ioctl() >>>>>>> hci_dev_close() >>>>>>> hci_dev_do_close() >>>>>>> hci_dev_lock(hdev); >>>>>>> inquiry_cache_flush(); >>>>>>> hci_conn_hash_flush(); >>>>>>> hci_conn_del() >>>>>>> cancel_delayed_work_sync() >>>>>>> hci_conn_timeout() >>>>>>> hci_dev_lock(hdev); /* DEADLOCK */ >>>>>> >>>>>> >>>>>> I am actually not sure that hci_conn_timeout locks hdev. Why do you >>>>>> think >>>>>> so? >>>>> >>>>> >>>>> By reading the source, printk and suffering through the deadlock. It's >>>>> especially painfull when using a bt-keyboard and systemd, because >>>>> systemd tries 4 times (~ some minutes) to kill bluetoothd before it >>>>> marks the service as failed and finally continues to shut down. >>>> >>>> >>>> hci_conn_timeout does lock the device. See the source. But the problem >>> >>> >>> I think you need to check commit e72acc13c770a82b4ce4a07e9716f29320eae0f8 >>> >>> commit e72acc13c770a82b4ce4a07e9716f29320eae0f8 >>> Author: Andre Guedes<andre.guedes@xxxxxxxxxxxxx> >>> Date: Fri Jan 27 19:42:03 2012 -0300 >>> >>> Bluetooth: Remove unneeded locking >>> >>> We don't need locking hdev in hci_conn_timeout() since it doesn't >>> access any hdev's shared resources, it basically queues HCI commands. >> >> >> So if the locks in hci_conn_timeout() aren't needed, your commit which >> removes them should go to the stable tree because it fixes a painful >> deadlock. > > > Oh, sorry, that patch is not from you, your first name is only similiar. > I've added the author to cc, just in case the lock might still be needed in > 3.3 if no other patches (from 3.4) besides that one are applied. It is still applicable. It was applied to bluetooth-next tree a week after 3.3 merge window was closed. This is the reason why it is not present in 3.3. BR, Andre -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
