Comment 2 for bug 1428548

I also found that an rfcomm device was not properly released. I see the following in dmesg:

Nov 4 17:24:22 live kernel: [75732.976759] ------------[ cut here ]------------
Nov 4 17:24:22 live kernel: [75732.976793] WARNING: CPU: 2 PID: 47 at /build/linux-rwKq_7/linux-3.13.0/drivers/tty/tty_port.c:145 tty_port_destructor+0x83/0x90()
Nov 4 17:24:22 live kernel: [75732.976803] Modules linked in: ipt_MASQUERADE iptable_nat nf_nat_ipv4 nf_nat ipt_REJECT xt_CHECKSUM iptable_mangle bridge stp llc ip6table_filter ip6_tables ebtable_nat ebtables xt_owner nf_conntrack_ipv4 nf_defrag_ipv4 xt_conntrack nf_conntrack xt_tcpudp iptable_filter ip_tables x_tables autofs4 dm_crypt arc4 iwlmvm(OX) mac80211(OX) snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_pcm dm_multipath intel_rapl kvm_intel scsi_dh snd_page_alloc kvm snd_seq_midi snd_seq_midi_event snd_rawmidi crct10dif_pclmul crc32_pclmul snd_seq ghash_clmulni_intel cryptd snd_seq_device snd_timer iwlwifi(OX) snd btusb(OX) rfcomm(OX) btbcm(OX) btintel(OX) bnep(OX) cfg80211(OX) cmac soundcore shpchp bluetooth(OX) compat(OX) i2c_scmi parport_pc ppdev lp mac_hid parport i2c_dev coretemp nfsd auth_rpcgss nfs_acl nfs lockd sunrpc fscache squashfs overlayfs nls_iso8859_1 hid_generic usbhid hid usb_storage igb dca ahci ptp i915(OX) pps_core sdhci_pci drm_mipi_dsi(OX) i2c_algo_bit drm_kms_helper(OX) sdhci libahci drm(OX) video(OX)
Nov 4 17:24:22 live kernel: [75732.977143] CPU: 2 PID: 47 Comm: kworker/2:1 Tainted: G OX 3.13.0-54-generic #0
Nov 4 17:24:22 live kernel: [75732.977154] Hardware name: N/A N/A/COMe-cBTi6R, BIOS BSCIA_PLX041.105.E38 X64 07/28/2015
Nov 4 17:24:22 live kernel: [75732.977173] Workqueue: events release_one_tty
Nov 4 17:24:22 live kernel: [75732.977184] 0000000000000009 ffff880273bb7d60 ffffffff817232a4 0000000000000000
Nov 4 17:24:22 live kernel: [75732.977207] ffff880273bb7d98 ffffffff8106784d ffff8801f438c56c ffff8801f438c400
Nov 4 17:24:22 live kernel: [75732.977227] ffff88027281bc00 0000000000000000 0000000000000080 ffff880273bb7da8
Nov 4 17:24:22 live kernel: [75732.977248] Call Trace:
Nov 4 17:24:22 live kernel: [75732.977273] [<ffffffff817232a4>] dump_stack+0x45/0x56
Nov 4 17:24:22 live kernel: [75732.977295] [<ffffffff8106784d>] warn_slowpath_common+0x7d/0xa0
Nov 4 17:24:22 live kernel: [75732.977314] [<ffffffff8106792a>] warn_slowpath_null+0x1a/0x20
Nov 4 17:24:22 live kernel: [75732.977333] [<ffffffff81455d33>] tty_port_destructor+0x83/0x90
Nov 4 17:24:22 live kernel: [75732.977351] [<ffffffff8145664c>] tty_port_put+0x2c/0x30
Nov 4 17:24:22 live kernel: [75732.977396] [<ffffffffa04460c8>] rfcomm_tty_cleanup+0x68/0x70 [rfcomm]
Nov 4 17:24:22 live kernel: [75732.977417] [<ffffffff8144b4d4>] release_one_tty+0x34/0xc0
Nov 4 17:24:22 live kernel: [75732.977439] [<ffffffff81083b22>] process_one_work+0x182/0x450
Nov 4 17:24:22 live kernel: [75732.977459] [<ffffffff81084911>] worker_thread+0x121/0x410
Nov 4 17:24:22 live kernel: [75732.977479] [<ffffffff810847f0>] ? rescuer_thread+0x430/0x430
Nov 4 17:24:22 live kernel: [75732.977498] [<ffffffff8108b702>] kthread+0xd2/0xf0
Nov 4 17:24:22 live kernel: [75732.977518] [<ffffffff8108b630>] ? kthread_create_on_node+0x1c0/0x1c0
Nov 4 17:24:22 live kernel: [75732.977537] [<ffffffff81733ce8>] ret_from_fork+0x58/0x90
Nov 4 17:24:22 live kernel: [75732.977556] [<ffffffff8108b630>] ? kthread_create_on_node+0x1c0/0x1c0
Nov 4 17:24:22 live kernel: [75732.977568] ---[ end trace 6a723aaafb1c166a ]---
Nov 4 17:24:22 live ModemManager[973]: <info> Creating modem with plugin 'Generic' and '1' ports
Nov 4 17:24:22 live ModemManager[973]: <warn> Could not grab port (tty/rfcomm0): 'Cannot add port 'tty/rfcomm0', unhandled serial type'
Nov 4 17:24:22 live ModemManager[973]: <warn> Couldn't create modem for device at '/sys/devices/pci0000:00/0000:00:14.0/usb1/1-3/1-3.4': Failed to find primary AT port
Nov 4 17:25:13 live kernel: [75783.080187] ------------[ cut here ]------------