Octavian Purdila cf33e77b76 Bluetooth: Fix RFCOMM session reference counting issue ... There is an imbalance in the rfcomm_session_hold / rfcomm_session_put operations which causes the following crash: [ 685.010159] BUG: unable to handle kernel paging request at 6b6b6b6b [ 685.010169] IP: [<c149d76d>] rfcomm_process_dlcs+0x1b/0x15e [ 685.010181] *pdpt = 000000002d665001 *pde = 0000000000000000 [ 685.010191] Oops: 0000 [#1] PREEMPT SMP [ 685.010247] [ 685.010255] Pid: 947, comm: krfcommd Tainted: G C 3.0.16-mid8-dirty #44 [ 685.010266] EIP: 0060:[<c149d76d>] EFLAGS: 00010246 CPU: 1 [ 685.010274] EIP is at rfcomm_process_dlcs+0x1b/0x15e [ 685.010281] EAX: e79f551c EBX: 6b6b6b6b ECX: 00000007 EDX: e79f40b4 [ 685.010288] ESI: e79f4060 EDI: ed4e1f70 EBP: ed4e1f68 ESP: ed4e1f50 [ 685.010295] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 [ 685.010303] Process krfcommd (pid: 947, ti=ed4e0000 task=ed43e5e0 task.ti=ed4e0000) [ 685.010308] Stack: [ 685.010312] ed4e1f68 c149eb53 e5925150 e79f4060 ed500000 ed4e1f70 ed4e1f80 c149ec10 [ 685.010331] 00000000 ed43e5e0 00000000 ed4e1f90 ed4e1f9c c149ec87 0000bf54 00000000 [ 685.010348] 00000000 ee03bf54 c149ec37 ed4e1fe4 c104fe01 00000000 00000000 00000000 [ 685.010367] Call Trace: [ 685.010376] [<c149eb53>] ? rfcomm_process_rx+0x6e/0x74 [ 685.010387] [<c149ec10>] rfcomm_process_sessions+0xb7/0xde [ 685.010398] [<c149ec87>] rfcomm_run+0x50/0x6d [ 685.010409] [<c149ec37>] ? rfcomm_process_sessions+0xde/0xde [ 685.010419] [<c104fe01>] kthread+0x63/0x68 [ 685.010431] [<c104fd9e>] ? __init_kthread_worker+0x42/0x42 [ 685.010442] [<c14dae82>] kernel_thread_helper+0x6/0xd This issue has been brought up earlier here: https://lkml.org/lkml/2011/5/21/127 The issue appears to be the rfcomm_session_put in rfcomm_recv_ua. This operation doesn't seem be to required as for the non-initiator case we have the rfcomm_process_rx doing an explicit put and in the initiator case the last dlc_unlink will drive the reference counter to 0. There have been several attempts to fix these issue: 6c2718d Bluetooth: Do not call rfcomm_session_put() for RFCOMM UA on closed socket 683d949 Bluetooth: Never deallocate a session when some DLC points to it but AFAICS they do not fix the issue just make it harder to reproduce. Signed-off-by: Octavian Purdila <octavian.purdila@intel.com> Signed-off-by: Gopala Krishna Murala <gopala.krishna.murala@intel.com> Acked-by: Marcel Holtmann <marcel@holtmann.org> Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>		2012-02-15 13:09:26 +02:00
..
Kconfig	Bluetooth: Always compile SCO and L2CAP in Bluetooth Core	2011-12-21 02:21:08 -02:00
Makefile	[Bluetooth] Move CRC table into RFCOMM core	2005-10-28 19:20:36 +02:00
core.c	Bluetooth: Fix RFCOMM session reference counting issue	2012-02-15 13:09:26 +02:00
sock.c	Bluetooth: silence lockdep warning	2012-02-15 13:09:26 +02:00
tty.c	Bluetooth: Fix context in RFCOMM tty	2012-01-02 22:19:29 -02:00