Re: [PATCH] usb: gadget: f_fs: Fix possibe deadlock
Hi Michal,
On 8 December 2016 at 23:18, Michal Nazarewicz wrote:
> On Thu, Dec 08 2016, Baolin Wang wrote:
>> When system try to close /dev/usb-ffs/adb/ep0 on one core, at the same
>> time another core try to attach new UDC, which will cause deadlock as
>> below scenario. Thus we should release ffs lock before issuing
>> unregister_gadget_item().
>>
>> [ 52.642225] c1 ==
>> [ 52.642228] c1 [ INFO: possible circular locking dependency detected ]
>> [ 52.642236] c1 4.4.6+ #1 Tainted: GW O
>> [ 52.642241] c1 ---
>> [ 52.642245] c1 usb ffs open/2808 is trying to acquire lock:
>> [ 52.642270] c0 (udc_lock){+.+.+.}, at: []
>> usb_gadget_unregister_driver+0x3c/0xc8
>> [ 52.642272] c1 but task is already holding lock:
>> [ 52.642283] c0 (ffs_lock){+.+.+.}, at: []
>> ffs_data_clear+0x30/0x140
>> [ 52.642285] c1 which lock already depends on the new lock.
>> [ 52.642287] c1
>>the existing dependency chain (in reverse order) is:
>> [ 52.642295] c0
>> -> #1 (ffs_lock){+.+.+.}:
>> [ 52.642307] c0[] __lock_acquire+0x20f0/0x2238
>> [ 52.642314] c0[] lock_acquire+0xe4/0x298
>> [ 52.642322] c0[] mutex_lock_nested+0x7c/0x3cc
>> [ 52.642328] c0[] ffs_func_bind+0x504/0x6e8
>> [ 52.642334] c0[] usb_add_function+0x84/0x184
>> [ 52.642340] c0[]
>> configfs_composite_bind+0x264/0x39c
>> [ 52.642346] c0[] udc_bind_to_driver+0x58/0x11c
>> [ 52.642352] c0[] usb_udc_attach_driver+0x90/0xc8
>> [ 52.642358] c0[]
>> gadget_dev_desc_UDC_store+0xd4/0x128
>> [ 52.642369] c0[] configfs_write_file+0xd0/0x13c
>> [ 52.642376] c0[] vfs_write+0xb8/0x214
>> [ 52.642381] c0[] SyS_write+0x54/0xb0
>> [ 52.642388] c0[] el0_svc_naked+0x24/0x28
>> [ 52.642395] c0
>> -> #0 (udc_lock){+.+.+.}:
>> [ 52.642401] c0[] print_circular_bug+0x84/0x2e4
>> [ 52.642407] c0[] __lock_acquire+0x2138/0x2238
>> [ 52.642412] c0[] lock_acquire+0xe4/0x298
>> [ 52.642420] c0[] mutex_lock_nested+0x7c/0x3cc
>> [ 52.642427] c0[]
>> usb_gadget_unregister_driver+0x3c/0xc8
>> [ 52.642432] c0[]
>> unregister_gadget_item+0x28/0x44
>> [ 52.642439] c0[] ffs_data_clear+0x138/0x140
>> [ 52.642444] c0[] ffs_data_reset+0x20/0x6c
>> [ 52.642450] c0[] ffs_data_closed+0xac/0x12c
>> [ 52.642454] c0[] ffs_ep0_release+0x20/0x2c
>> [ 52.642460] c0[] __fput+0xb0/0x1f4
>> [ 52.642466] c0[] fput+0x20/0x2c
>> [ 52.642473] c0[] task_work_run+0xb4/0xe8
>> [ 52.642482] c0[] do_exit+0x360/0xb9c
>> [ 52.642487] c0[] do_group_exit+0x4c/0xb0
>> [ 52.642494] c0[] get_signal+0x380/0x89c
>> [ 52.642501] c0[] do_signal+0x154/0x518
>> [ 52.642507] c0[] do_notify_resume+0x70/0x78
>> [ 52.642512] c0[] work_pending+0x1c/0x20
>> [ 52.642514] c1
>> other info that might help us debug this:
>> [ 52.642517] c1 Possible unsafe locking scenario:
>> [ 52.642518] c1CPU0CPU1
>> [ 52.642520] c1
>> [ 52.642525] c0 lock(ffs_lock);
>> [ 52.642529] c0lock(udc_lock);
>> [ 52.642533] c0lock(ffs_lock);
>> [ 52.642537] c0 lock(udc_lock);
>> [ 52.642539] c1
>> *** DEADLOCK ***
>> [ 52.642543] c1 1 lock held by usb ffs open/2808:
>> [ 52.642555] c0 #0: (ffs_lock){+.+.+.}, at: []
>> ffs_data_clear+0x30/0x140
>> [ 52.642557] c1 stack backtrace:
>> [ 52.642563] c1 CPU: 1 PID: 2808 Comm: usb ffs open Tainted: G
>> [ 52.642565] c1 Hardware name: Spreadtrum SP9860g Board (DT)
>> [ 52.642568] c1 Call trace:
>> [ 52.642573] c1 [] dump_backtrace+0x0/0x170
>> [ 52.642577] c1 [] show_stack+0x20/0x28
>> [ 52.642583] c1 [] dump_stack+0xa8/0xe0
>> [ 52.642587] c1 [] print_circular_bug+0x1fc/0x2e4
>> [ 52.642591] c1 [] __lock_acquire+0x2138/0x2238
>> [ 52.642595] c1 [] lock_acquire+0xe4/0x298
>> [ 52.642599] c1 [] mutex_lock_nested+0x7c/0x3cc
>> [ 52.642604] c1 [] usb_gadget_unregister_driver+0x3c/0xc8
>> [ 52.642608] c1 [] unregister_gadget_item+0x28/0x44
>> [ 52.642613] c1 [] ffs_data_clear+0x138/0x140
>> [ 52.642618] c1 [] ffs_data_reset+0x20/0x6c
>> [ 52.642621] c1 [] ffs_data_closed+0xac/0x12c
>> [ 52.642625] c1 [] ffs_ep0_release+0x20/0x2c
>> [ 52.642629] c1 [] __fput+0xb0/0x1f4
>> [ 52.642633] c1 [] fput+0x20/0x2c
>> [ 52.642636] c1 [] task_work_run+0xb4/0xe8
>> [ 52.642640] c1 [] do_exit+0x360/0xb9c
>> [ 52.642644] c1 [] do_group_exit+0x4c/0xb0
>> [ 52.642647] c1 [] get_signal+0x380/0x89c
>> [ 52.642651] c1 [] do_signal+0x154/0x518
>> [ 52.642656] c1 []
Re: [PATCH] usb: gadget: f_fs: Fix possibe deadlock
On Thu, Dec 08 2016, Baolin Wang wrote:
> When system try to close /dev/usb-ffs/adb/ep0 on one core, at the same
> time another core try to attach new UDC, which will cause deadlock as
> below scenario. Thus we should release ffs lock before issuing
> unregister_gadget_item().
>
> [ 52.642225] c1 ==
> [ 52.642228] c1 [ INFO: possible circular locking dependency detected ]
> [ 52.642236] c1 4.4.6+ #1 Tainted: GW O
> [ 52.642241] c1 ---
> [ 52.642245] c1 usb ffs open/2808 is trying to acquire lock:
> [ 52.642270] c0 (udc_lock){+.+.+.}, at: []
> usb_gadget_unregister_driver+0x3c/0xc8
> [ 52.642272] c1 but task is already holding lock:
> [ 52.642283] c0 (ffs_lock){+.+.+.}, at: []
> ffs_data_clear+0x30/0x140
> [ 52.642285] c1 which lock already depends on the new lock.
> [ 52.642287] c1
>the existing dependency chain (in reverse order) is:
> [ 52.642295] c0
> -> #1 (ffs_lock){+.+.+.}:
> [ 52.642307] c0[] __lock_acquire+0x20f0/0x2238
> [ 52.642314] c0[] lock_acquire+0xe4/0x298
> [ 52.642322] c0[] mutex_lock_nested+0x7c/0x3cc
> [ 52.642328] c0[] ffs_func_bind+0x504/0x6e8
> [ 52.642334] c0[] usb_add_function+0x84/0x184
> [ 52.642340] c0[]
> configfs_composite_bind+0x264/0x39c
> [ 52.642346] c0[] udc_bind_to_driver+0x58/0x11c
> [ 52.642352] c0[] usb_udc_attach_driver+0x90/0xc8
> [ 52.642358] c0[]
> gadget_dev_desc_UDC_store+0xd4/0x128
> [ 52.642369] c0[] configfs_write_file+0xd0/0x13c
> [ 52.642376] c0[] vfs_write+0xb8/0x214
> [ 52.642381] c0[] SyS_write+0x54/0xb0
> [ 52.642388] c0[] el0_svc_naked+0x24/0x28
> [ 52.642395] c0
> -> #0 (udc_lock){+.+.+.}:
> [ 52.642401] c0[] print_circular_bug+0x84/0x2e4
> [ 52.642407] c0[] __lock_acquire+0x2138/0x2238
> [ 52.642412] c0[] lock_acquire+0xe4/0x298
> [ 52.642420] c0[] mutex_lock_nested+0x7c/0x3cc
> [ 52.642427] c0[]
> usb_gadget_unregister_driver+0x3c/0xc8
> [ 52.642432] c0[] unregister_gadget_item+0x28/0x44
> [ 52.642439] c0[] ffs_data_clear+0x138/0x140
> [ 52.642444] c0[] ffs_data_reset+0x20/0x6c
> [ 52.642450] c0[] ffs_data_closed+0xac/0x12c
> [ 52.642454] c0[] ffs_ep0_release+0x20/0x2c
> [ 52.642460] c0[] __fput+0xb0/0x1f4
> [ 52.642466] c0[] fput+0x20/0x2c
> [ 52.642473] c0[] task_work_run+0xb4/0xe8
> [ 52.642482] c0[] do_exit+0x360/0xb9c
> [ 52.642487] c0[] do_group_exit+0x4c/0xb0
> [ 52.642494] c0[] get_signal+0x380/0x89c
> [ 52.642501] c0[] do_signal+0x154/0x518
> [ 52.642507] c0[] do_notify_resume+0x70/0x78
> [ 52.642512] c0[] work_pending+0x1c/0x20
> [ 52.642514] c1
> other info that might help us debug this:
> [ 52.642517] c1 Possible unsafe locking scenario:
> [ 52.642518] c1CPU0CPU1
> [ 52.642520] c1
> [ 52.642525] c0 lock(ffs_lock);
> [ 52.642529] c0lock(udc_lock);
> [ 52.642533] c0lock(ffs_lock);
> [ 52.642537] c0 lock(udc_lock);
> [ 52.642539] c1
> *** DEADLOCK ***
> [ 52.642543] c1 1 lock held by usb ffs open/2808:
> [ 52.642555] c0 #0: (ffs_lock){+.+.+.}, at: []
> ffs_data_clear+0x30/0x140
> [ 52.642557] c1 stack backtrace:
> [ 52.642563] c1 CPU: 1 PID: 2808 Comm: usb ffs open Tainted: G
> [ 52.642565] c1 Hardware name: Spreadtrum SP9860g Board (DT)
> [ 52.642568] c1 Call trace:
> [ 52.642573] c1 [] dump_backtrace+0x0/0x170
> [ 52.642577] c1 [] show_stack+0x20/0x28
> [ 52.642583] c1 [] dump_stack+0xa8/0xe0
> [ 52.642587] c1 [] print_circular_bug+0x1fc/0x2e4
> [ 52.642591] c1 [] __lock_acquire+0x2138/0x2238
> [ 52.642595] c1 [] lock_acquire+0xe4/0x298
> [ 52.642599] c1 [] mutex_lock_nested+0x7c/0x3cc
> [ 52.642604] c1 [] usb_gadget_unregister_driver+0x3c/0xc8
> [ 52.642608] c1 [] unregister_gadget_item+0x28/0x44
> [ 52.642613] c1 [] ffs_data_clear+0x138/0x140
> [ 52.642618] c1 [] ffs_data_reset+0x20/0x6c
> [ 52.642621] c1 [] ffs_data_closed+0xac/0x12c
> [ 52.642625] c1 [] ffs_ep0_release+0x20/0x2c
> [ 52.642629] c1 [] __fput+0xb0/0x1f4
> [ 52.642633] c1 [] fput+0x20/0x2c
> [ 52.642636] c1 [] task_work_run+0xb4/0xe8
> [ 52.642640] c1 [] do_exit+0x360/0xb9c
> [ 52.642644] c1 [] do_group_exit+0x4c/0xb0
> [ 52.642647] c1 [] get_signal+0x380/0x89c
> [ 52.642651] c1 [] do_signal+0x154/0x518
> [ 52.642656] c1 [] do_notify_resume+0x70/0x78
> [ 52.642659] c1 [] work_pending+0x1c/0x20
>
> Signed-off-by: Baolin Wang
Acked-by: Michal Nazarewicz
> ---
> drivers/usb/gadget/func
[PATCH] usb: gadget: f_fs: Fix possibe deadlock
When system try to close /dev/usb-ffs/adb/ep0 on one core, at the same
time another core try to attach new UDC, which will cause deadlock as
below scenario. Thus we should release ffs lock before issuing
unregister_gadget_item().
[ 52.642225] c1 ==
[ 52.642228] c1 [ INFO: possible circular locking dependency detected ]
[ 52.642236] c1 4.4.6+ #1 Tainted: GW O
[ 52.642241] c1 ---
[ 52.642245] c1 usb ffs open/2808 is trying to acquire lock:
[ 52.642270] c0 (udc_lock){+.+.+.}, at: []
usb_gadget_unregister_driver+0x3c/0xc8
[ 52.642272] c1 but task is already holding lock:
[ 52.642283] c0 (ffs_lock){+.+.+.}, at: []
ffs_data_clear+0x30/0x140
[ 52.642285] c1 which lock already depends on the new lock.
[ 52.642287] c1
the existing dependency chain (in reverse order) is:
[ 52.642295] c0
-> #1 (ffs_lock){+.+.+.}:
[ 52.642307] c0[] __lock_acquire+0x20f0/0x2238
[ 52.642314] c0[] lock_acquire+0xe4/0x298
[ 52.642322] c0[] mutex_lock_nested+0x7c/0x3cc
[ 52.642328] c0[] ffs_func_bind+0x504/0x6e8
[ 52.642334] c0[] usb_add_function+0x84/0x184
[ 52.642340] c0[]
configfs_composite_bind+0x264/0x39c
[ 52.642346] c0[] udc_bind_to_driver+0x58/0x11c
[ 52.642352] c0[] usb_udc_attach_driver+0x90/0xc8
[ 52.642358] c0[]
gadget_dev_desc_UDC_store+0xd4/0x128
[ 52.642369] c0[] configfs_write_file+0xd0/0x13c
[ 52.642376] c0[] vfs_write+0xb8/0x214
[ 52.642381] c0[] SyS_write+0x54/0xb0
[ 52.642388] c0[] el0_svc_naked+0x24/0x28
[ 52.642395] c0
-> #0 (udc_lock){+.+.+.}:
[ 52.642401] c0[] print_circular_bug+0x84/0x2e4
[ 52.642407] c0[] __lock_acquire+0x2138/0x2238
[ 52.642412] c0[] lock_acquire+0xe4/0x298
[ 52.642420] c0[] mutex_lock_nested+0x7c/0x3cc
[ 52.642427] c0[]
usb_gadget_unregister_driver+0x3c/0xc8
[ 52.642432] c0[] unregister_gadget_item+0x28/0x44
[ 52.642439] c0[] ffs_data_clear+0x138/0x140
[ 52.642444] c0[] ffs_data_reset+0x20/0x6c
[ 52.642450] c0[] ffs_data_closed+0xac/0x12c
[ 52.642454] c0[] ffs_ep0_release+0x20/0x2c
[ 52.642460] c0[] __fput+0xb0/0x1f4
[ 52.642466] c0[] fput+0x20/0x2c
[ 52.642473] c0[] task_work_run+0xb4/0xe8
[ 52.642482] c0[] do_exit+0x360/0xb9c
[ 52.642487] c0[] do_group_exit+0x4c/0xb0
[ 52.642494] c0[] get_signal+0x380/0x89c
[ 52.642501] c0[] do_signal+0x154/0x518
[ 52.642507] c0[] do_notify_resume+0x70/0x78
[ 52.642512] c0[] work_pending+0x1c/0x20
[ 52.642514] c1
other info that might help us debug this:
[ 52.642517] c1 Possible unsafe locking scenario:
[ 52.642518] c1CPU0CPU1
[ 52.642520] c1
[ 52.642525] c0 lock(ffs_lock);
[ 52.642529] c0lock(udc_lock);
[ 52.642533] c0lock(ffs_lock);
[ 52.642537] c0 lock(udc_lock);
[ 52.642539] c1
*** DEADLOCK ***
[ 52.642543] c1 1 lock held by usb ffs open/2808:
[ 52.642555] c0 #0: (ffs_lock){+.+.+.}, at: []
ffs_data_clear+0x30/0x140
[ 52.642557] c1 stack backtrace:
[ 52.642563] c1 CPU: 1 PID: 2808 Comm: usb ffs open Tainted: G
[ 52.642565] c1 Hardware name: Spreadtrum SP9860g Board (DT)
[ 52.642568] c1 Call trace:
[ 52.642573] c1 [] dump_backtrace+0x0/0x170
[ 52.642577] c1 [] show_stack+0x20/0x28
[ 52.642583] c1 [] dump_stack+0xa8/0xe0
[ 52.642587] c1 [] print_circular_bug+0x1fc/0x2e4
[ 52.642591] c1 [] __lock_acquire+0x2138/0x2238
[ 52.642595] c1 [] lock_acquire+0xe4/0x298
[ 52.642599] c1 [] mutex_lock_nested+0x7c/0x3cc
[ 52.642604] c1 [] usb_gadget_unregister_driver+0x3c/0xc8
[ 52.642608] c1 [] unregister_gadget_item+0x28/0x44
[ 52.642613] c1 [] ffs_data_clear+0x138/0x140
[ 52.642618] c1 [] ffs_data_reset+0x20/0x6c
[ 52.642621] c1 [] ffs_data_closed+0xac/0x12c
[ 52.642625] c1 [] ffs_ep0_release+0x20/0x2c
[ 52.642629] c1 [] __fput+0xb0/0x1f4
[ 52.642633] c1 [] fput+0x20/0x2c
[ 52.642636] c1 [] task_work_run+0xb4/0xe8
[ 52.642640] c1 [] do_exit+0x360/0xb9c
[ 52.642644] c1 [] do_group_exit+0x4c/0xb0
[ 52.642647] c1 [] get_signal+0x380/0x89c
[ 52.642651] c1 [] do_signal+0x154/0x518
[ 52.642656] c1 [] do_notify_resume+0x70/0x78
[ 52.642659] c1 [] work_pending+0x1c/0x20
Signed-off-by: Baolin Wang
---
drivers/usb/gadget/function/f_fs.c |8 ++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/usb/gadget/function/f_fs.c
b/drivers/usb/gadget/function/f_fs.c
index 0780d83..93de3b9 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/fun
