On 03/21/2016, 04:58 PM, Jiri Slaby wrote: > Hello, > > On 03/18/2016, 09:52 PM, Tejun Heo wrote: >> On Thu, Mar 17, 2016 at 01:00:13PM +0100, Jiri Slaby wrote: >>>>> I have not done that yet, but today, I see: >>>>> destroy_workqueue: name='req_hci0' pwq=ffff88002f590300 >>>>> wq->dfl_pwq=ffff88002f591e00 pwq->refcnt=2 pwq->nr_active=0 delayed_works: >>>>> pwq 12: cpus=0-1 node=0 flags=0x4 nice=-20 active=0/1 >>>>> in-flight: 18568:wq_barrier_func >>>> >>>> So, this means that there's flush_work() racing against workqueue >>>> destruction, which can't be safe. :( >>> >>> But I cannot trigger the WARN_ONs in the attached patch, so I am >>> confused how this can happen :(. (While I am still seeing the destroy >>> WARNINGs.) >> >> So, no operations should be in progress when destroy_workqueue() is >> called. If somebody was flushing a work item, the flush call must >> have returned before destroy_workqueue() was invoked, which doesn't >> seem to be the case here. Can you trigger BUG_ON() or sysrq-t when >> the above triggers? There must be a task which is flushing a work >> item there and it shouldn't be difficult to pinpoint what's going on >> from it. > > The output of sysrq-t is here (> 200k), but I cannot see anything > suspicious in it: > http://www.fi.muni.cz/~xslaby/sklad/panics/jctl.txt Hmm, so I seem I cannot reproduce with this hunk: --- a/net/bluetooth/hci_core.c +++ b/net/bluetooth/hci_core.c @@ -3139,10 +3139,10 @@ void hci_unregister_dev(struct hci_dev *hdev) list_del(&hdev->list); write_unlock(&hci_dev_list_lock); - hci_dev_do_close(hdev); - cancel_work_sync(&hdev->power_on); + hci_dev_do_close(hdev); + if (!test_bit(HCI_INIT, &hdev->flags) && !hci_dev_test_flag(hdev, HCI_SETUP) && !hci_dev_test_flag(hdev, HCI_CONFIG)) { I cannot explain why though. I do not see how it matters in this particular case... Dmitry, could you apply it too? But I don't know how often you see the warning. PS. next on the table is the gsm tty warning. thanks, -- js suse labs -- 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
