[audio/bluetooth signal is lost, no error/debugging messages. (i enabled some debugging options in my 3.12.6 kernel). i cannot re-establish the bluetooth connection, so there probably is something wrong with the usb subsystem. so i decide to unplug the usb dongle.] 16:13:41 kernel: hub 3-0:1.0: state 7 ports 4 chg 0000 evt 0002 16:13:41 kernel: ohci-pci 0000:00:13.1: GetStatus roothub.portstatus [0] = 0x00030100 PESC CSC PPS 16:13:41 kernel: hub 3-0:1.0: port 1, status 0100, change 0003, 12 Mb/s 16:13:41 kernel: usb 3-1: USB disconnect, device number 5 16:13:41 kernel: usb 3-1: unregistering device 16:13:41 kernel: usb 3-1: unregistering interface 3-1:1.0 16:13:41 kernel: kobject: 'pcmC1D0p' (ffff8800479fd210): kobject_uevent_env 16:13:41 kernel: kobject: 'pcmC1D0p' (ffff8800479fd210): fill_kobj_path: path = '/devices/pci0000:00/0000:00:13.1/usb3/3-1/3-1:1.0/sound/card1/pcmC1D0p' 16:13:41 kernel: kobject: 'pcmC1D0p' (ffff8800479fd210): kobject_cleanup, parent (null) 16:13:41 kernel: kobject: 'pcmC1D0p' (ffff8800479fd210): calling ktype release 16:13:41 kernel: kobject: 'pcmC1D0p': free name 16:13:41 kernel: kobject: 'pcmC1D0c' (ffff88004785d410): kobject_uevent_env 16:13:41 kernel: kobject: 'pcmC1D0c' (ffff88004785d410): fill_kobj_path: path = '/devices/pci0000:00/0000:00:13.1/usb3/3-1/3-1:1.0/sound/card1/pcmC1D0c' 16:13:41 kernel: kobject: 'pcmC1D0c' (ffff88004785d410): kobject_cleanup, parent (null) 16:13:41 kernel: kobject: 'pcmC1D0c' (ffff88004785d410): calling ktype release 16:13:41 kernel: kobject: 'pcmC1D0c': free name 16:13:41 kernel: kobject: 'controlC1' (ffff88004785da10): kobject_uevent_env 16:13:41 kernel: kobject: 'controlC1' (ffff88004785da10): fill_kobj_path: path = '/devices/pci0000:00/0000:00:13.1/usb3/3-1/3-1:1.0/sound/card1/controlC1' 16:13:41 kernel: kobject: 'controlC1' (ffff88004785da10): kobject_cleanup, parent (null) 16:13:41 kernel: kobject: 'controlC1' (ffff88004785da10): calling ktype release 16:13:41 kernel: kobject: 'controlC1': free name 16:13:41 kernel: kobject: 'card1' (ffff8800479fd010): kobject_uevent_env 16:13:41 kernel: kobject: 'card1' (ffff8800479fd010): fill_kobj_path: path = '/devices/pci0000:00/0000:00:13.1/usb3/3-1/3-1:1.0/sound/card1' 16:13:41 kernel: kobject: 'sound' (ffff880046679c00): kobject_cleanup, parent ffff88004676fc40 16:13:41 kernel: kobject: 'sound' (ffff880046679c00): auto cleanup kobject_del 16:13:41 kernel: kobject: 'sound' (ffff880046679c00): calling ktype release 16:13:41 kernel: kobject: 'sound': free name 16:13:41 kernel: kobject: 'card1' (ffff8800479fd010): kobject_cleanup, parent (null) 16:13:41 kernel: kobject: 'card1' (ffff8800479fd010): calling ktype release 16:13:41 kernel: kobject: 'card1': free name 16:13:42 kernel: ALSA sound/usb/endpoint.c:501 timeout: still 3 active urbs on EP #3 16:13:42 kernel: kobject: '3-1:1.0' (ffff88004676fc40): kobject_uevent_env 16:13:42 kernel: kobject: '3-1:1.0' (ffff88004676fc40): fill_kobj_path: path = '/devices/pci0000:00/0000:00:13.1/usb3/3-1/3-1:1.0' 16:13:42 kernel: usb 3-1: unregistering interface 3-1:1.1 16:13:42 kernel: kobject: '3-1:1.1' (ffff88004676f240): kobject_uevent_env 16:13:42 kernel: kobject: '3-1:1.1' (ffff88004676f240): fill_kobj_path: path = '/devices/pci0000:00/0000:00:13.1/usb3/3-1/3-1:1.1' 16:13:42 kernel: usb 3-1: unregistering interface 3-1:1.2 16:13:42 kernel: kobject: 'ep_03' (ffff88002684f020): kobject_uevent_env 16:13:42 kernel: kobject: 'ep_03' (ffff88002684f020): kobject_uevent_env: filter function caused the event to drop! 16:13:42 kernel: kobject: 'ep_03' (ffff88002684f020): kobject_cleanup, parent (null) 16:13:42 kernel: kobject: 'ep_03' (ffff88002684f020): calling ktype release 16:13:42 kernel: kobject: 'ep_03': free name [then i try to reconnect the usb dongle, but the kernel doesn't detect the reconnection. instead, after a few minutes ...] 16:16:47 kernel: INFO: task khubd:359 blocked for more than 120 seconds. 16:16:47 kernel: Not tainted 3.12.6-gentoo #5 16:16:47 kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. 16:16:47 kernel: khubd D ffff88004dcf5800 0 359 2 0x00000000 16:16:47 kernel: ffff88004dd8f7a0 0000000000000046 3230000000000000 ffff88004d477230 16:16:47 kernel: ffff88004dccffd8 ffff88004dccffd8 ffff88004dd8f7a0 ffff88004dccffd8 16:16:47 kernel: 0000000000000400 0000000000000246 0000000000000002 0000000100240014 16:16:47 kernel: Call Trace: 16:16:47 kernel: [] ? ohci_urb_dequeue+0x75/0xd0 16:16:47 kernel: [] ? usb_kill_urb+0x6d/0xb0 16:16:47 kernel: [] ? abort_exclusive_wait+0xe0/0xe0 16:16:47 kernel: [] ? usb_hcd_flush_endpoint+0xd9/0x1d0 16:16:47 kernel: [] ? release_sysfs_dirent+0x62/0x110 16:16:47 kernel: [] ? usb_disable_endpoint+0x57/0xb0 16:16:47 kernel: [] ? usb_disable_interface+0x3c/0x50 16:16:47 kernel: [] ? usb_unbind_interface+0xf5/0x120 16:16:47 kernel: [] ? __device_release_driver+0x5d/0xd0 16:16:47 kernel: [] ? device_release_driver+0x25/0x40 16:16:47 kernel: [] ? bus_remove_device+0xdd/0x120 16:16:47 kernel: [] ? device_del+0x10d/0x190 16:16:47 kernel: [] ? usb_disable_device+0xa1/0x280 16:16:47 kernel: [] ? usb_disconnect+0xa5/0x1c0 16:16:47 kernel: [] ? hub_thread+0x4f7/0x1470 16:16:47 kernel: [] ? __schedule+0x246/0x5a0 16:16:47 kernel: [] ? __wake_up_common+0x4c/0x80 16:16:47 kernel: [] ? abort_exclusive_wait+0xe0/0xe0 16:16:47 kernel: [] ? usb_port_resume+0x500/0x500 16:16:47 kernel: [] ? kthread+0xb2/0xc0 16:16:47 kernel: [] ? kthread_freezable_should_stop+0x50/0x50 16:16:47 kernel: [] ? ret_from_fork+0x7a/0xb0 16:16:47 kernel: [] ? kthread_freezable_should_stop+0x50/0x50 [... and, in fact, "lsusb" says that it's still connected: Bus 003 Device 005: ID 046d:0a29 Logitech, Inc. ... but "lsusb -v" crashes/stalls, and possibly spits out this call trace ...] 16:18:47 kernel: INFO: task khubd:359 blocked for more than 120 seconds. 16:18:47 kernel: Not tainted 3.12.6-gentoo #5 16:18:47 kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. 16:18:47 kernel: khubd D ffff88004dcf5800 0 359 2 0x00000000 16:18:47 kernel: ffff88004dd8f7a0 0000000000000046 3230000000000000 ffff88004d477230 16:18:47 kernel: ffff88004dccffd8 ffff88004dccffd8 ffff88004dd8f7a0 ffff88004dccffd8 16:18:47 kernel: 0000000000000400 0000000000000246 0000000000000002 0000000100240014 16:18:47 kernel: Call Trace: 16:18:47 kernel: [] ? ohci_urb_dequeue+0x75/0xd0 16:18:47 kernel: [] ? usb_kill_urb+0x6d/0xb0 16:18:47 kernel: [] ? abort_exclusive_wait+0xe0/0xe0 16:18:47 kernel: [] ? usb_hcd_flush_endpoint+0xd9/0x1d0 16:18:47 kernel: [] ? release_sysfs_dirent+0x62/0x110 16:18:47 kernel: [] ? usb_disable_endpoint+0x57/0xb0 16:18:47 kernel: [] ? usb_disable_interface+0x3c/0x50 16:18:47 kernel: [] ? usb_unbind_interface+0xf5/0x120 16:18:47 kernel: [] ? __device_release_driver+0x5d/0xd0 16:18:47 kernel: [] ? device_release_driver+0x25/0x40 16:18:47 kernel: [] ? bus_remove_device+0xdd/0x120 16:18:47 kernel: [] ? device_del+0x10d/0x190 16:18:47 kernel: [] ? usb_disable_device+0xa1/0x280 16:18:47 kernel: [] ? usb_disconnect+0xa5/0x1c0 16:18:47 kernel: [] ? hub_thread+0x4f7/0x1470 16:18:47 kernel: [] ? __schedule+0x246/0x5a0 16:18:47 kernel: [] ? __wake_up_common+0x4c/0x80 16:18:47 kernel: [] ? abort_exclusive_wait+0xe0/0xe0 16:18:47 kernel: [] ? usb_port_resume+0x500/0x500 16:18:47 kernel: [] ? kthread+0xb2/0xc0 16:18:47 kernel: [] ? kthread_freezable_should_stop+0x50/0x50 16:18:47 kernel: [] ? ret_from_fork+0x7a/0xb0 16:18:47 kernel: [] ? kthread_freezable_should_stop+0x50/0x50 16:18:47 kernel: INFO: task lsusb:8207 blocked for more than 120 seconds. 16:18:47 kernel: Not tainted 3.12.6-gentoo #5 16:18:47 kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. 16:18:47 kernel: lsusb D 00000000ffffffff 0 8207 8018 0x00000004 16:18:47 kernel: ffff88004dd56750 0000000000000086 0000000300000000 ffffffff81a16480 16:18:47 kernel: ffff880027cabfd8 ffff880027cabfd8 ffff88004dd56750 ffff880027cabfd8 16:18:47 kernel: 00000001000280d0 0000000000000000 ffff880000000041 ffffffff81a788a0 16:18:47 kernel: Call Trace: 16:18:47 kernel: [] ? __d_lookup+0x12f/0x1b0 16:18:47 kernel: [] ? schedule_preempt_disabled+0x13/0x30 16:18:47 kernel: [] ? __mutex_lock_slowpath+0x97/0x140 16:18:47 kernel: [] ? driver_resume+0x10/0x10 16:18:47 kernel: [] ? usbdev_open+0xd4/0x1f0 16:18:47 kernel: [] ? chrdev_open+0xb7/0x1e0 16:18:47 kernel: [] ? cdev_put+0x20/0x20 16:18:47 kernel: [] ? do_dentry_open.isra.17+0x1de/0x260 16:18:47 kernel: [] ? finish_open+0x15/0x20 16:18:47 kernel: [] ? do_last.isra.71+0x619/0xd10 16:18:47 kernel: [] ? link_path_walk+0x78/0x960 16:18:47 kernel: [] ? __do_fault+0x3c2/0x4f0 16:18:47 kernel: [] ? path_openat+0xcb/0x660 16:18:47 kernel: [] ? preempt_schedule+0x3e/0x60 16:18:47 kernel: [] ? do_filp_open+0x45/0xb0 16:18:47 kernel: [] ? __alloc_fd+0xbd/0x120 16:18:47 kernel: [] ? do_sys_open+0x151/0x230 16:18:47 kernel: [] ? system_call_fastpath+0x16/0x1b [i am forced to reboot in order to get the usb-audio working again :'(.]