Re: BUG with linux 5.9.0 with dwc3 in gadget mode

[Ferry Toth <fntoth@gmail.com>]

Op 21-10-2020 om 21:50 schreef Thinh Nguyen:
> Ferry Toth wrote:
>> Op 21-10-2020 om 00:58 schreef Thinh Nguyen:
>>> Thinh Nguyen wrote:
>>>> Hi,
>>>>
>>>> Ferry Toth wrote:
>>>>> Op 20-10-2020 om 14:32 schreef Felipe Balbi:
>>>>>> Hi,
>>>>>>
>>>>>> Ferry Toth <fntoth@gmail.com> writes:
>>>>>>
>>>>>> 8< snip
>>>>>>
>>>>>>>>> [   12.657416] CR2: 0000000100000000
>>>>>>>>> [   12.660729] ---[ end trace 9b92dea6da33c71e ]---
>>>>>>>> It this something you can reproduce on your end? Ferry, can you get
>>>>>>>> dwc3
>>>>>>>> trace logs when this happens? ftrace_dump_on_oops may help here.
>>>>>>> I will do that tonight. Is flipping on ftrace_dump_on_oops
>>>>>>> sufficient or
>>>>>>> do I need to do more?
>>>>>> you'd have to enable dwc3 trace events first ;-)
>>>>>>
>>>>>>> BTW after posting this I found in host mode dwc3 is not working
>>>>>>> properly
>>>>>>> either. No oops, but no driver get loaded on device plug in.
>>>>>> okay
>>>>>>
>>>>> Ehem, you maybe only me to enable /dwc3/dwc3_ep_dequeue/enable:
>>>>>
>>>>> root@edison:/boot# uname -a
>>>>> Linux edison 5.9.0-edison-acpi-standard #1 SMP Mon Oct 19 20:17:04 UTC
>>>>> 2020 x86_64 x86_64 x86_64 GNU/Linux
>>>>> root@edison:/boot# echo 1 >
>>>>> /sys/kernel/debug/tracing/events/dwc3/dwc3_ep_dequeue/enable
>>>>> root@edison:/boot# echo 1 > /proc/sys/kernel/ftrace_dump_on_oops
>>>>> root@edison:/boot#
>>>>> root@edison:/boot# [ 2608.585323] BUG: kernel NULL pointer
>>>>> dereference, address: 0000000000000000
>>>>> [ 2608.592288] #PF: supervisor read access in kernel mode
>>>>> [ 2608.597419] #PF: error_code(0x0000) - not-present page
>>>>> [ 2608.602549] PGD 0 P4D 0
>>>>> [ 2608.605090] Oops: 0000 [#1] SMP PTI
>>>>> [ 2608.608580] CPU: 1 PID: 733 Comm: irq/15-dwc3 Not tainted
>>>>> 5.9.0-edison-acpi-standard #1
>>>>> [ 2608.616571] Hardware name: Intel Corporation Merrifield/BODEGA BAY,
>>>>> BIOS 542 2015.01.21:18.19.48
>>>>> [ 2608.625356] RIP: 0010:dwc3_gadget_ep_dequeue+0x41/0x1c0
>>>>> [ 2608.630580] Code: e9 51 01 00 00 4c 8d a3 30 01 00 00 4c 89 e7 e8
>>>>> 15 e6 42 00 49 8b 4e 48 49 89 c5 49 8d 46 48 48 8d 51 a0 48 39 c8 75
>>>>> 0f eb 2e <48> 8b 4a 60 48 8d 51 a0 48 39 c8 74 21 48 39 d5 75 ee 45 31
>>>>> f6 4c
>>>>> [ 2608.649320] RSP: 0018:ffffa838002a7c40 EFLAGS: 00010087
>>>>> [ 2608.654543] RAX: ffff9a5f4609c048 RBX: ffff9a5f46f48028 RCX:
>>>>> 0000000000000000
>>>>> [ 2608.661666] RDX: ffffffffffffffa0 RSI: 0000000000000008 RDI:
>>>>> ffff9a5f46f48158
>>>>> [ 2608.668790] RBP: ffff9a5f7bd09b40 R08: 00000000000002d8 R09:
>>>>> ffff9a5f7dd6a000
>>>>> [ 2608.675913] R10: ffffa838002a7d90 R11: ffff9a5f46f48300 R12:
>>>>> ffff9a5f46f48158
>>>>> [ 2608.683039] R13: 0000000000000046 R14: ffff9a5f4609c000 R15:
>>>>> ffff9a5f7ad77e00
>>>>> [ 2608.690165] FS:  0000000000000000(0000) GS:ffff9a5f7e300000(0000)
>>>>> knlGS:0000000000000000
>>>>> [ 2608.698244] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>>> [ 2608.703980] CR2: 0000000000000000 CR3: 000000003780a000 CR4:
>>>>> 00000000001006e0
>>>>> [ 2608.711102] Call Trace:
>>>>> [ 2608.713561]  usb_ep_dequeue+0x19/0x80
>>>>> [ 2608.717234]  u_audio_stop_capture+0x54/0x9a [u_audio]
>>>>> [ 2608.722289]  afunc_set_alt+0x73/0x80 [usb_f_uac2]
>>>> I took a look at how the audio function is handling switching alternate
>>>> setting and dequeuing endpoints, and I think I found the issue.
>>>>
>>>> Here's a snippet of the free_ep() code in u_audio.c:
>>>>
>>>> static inline void free_ep(struct uac_rtd_params *prm, struct usb_ep
>>>> *ep)
>>>> {
>>>>       .....
>>>>           for (i = 0; i < params->req_number; i++) {
>>>>                   if (prm->ureq[i].req) {
>>>>                           usb_ep_dequeue(ep, prm->ureq[i].req);
>>>>                           usb_ep_free_request(ep, prm->ureq[i].req);
>>>>                           prm->ureq[i].req = NULL;
>>>>                   }
>>>>           }
>>>>     ....
>>>>
>>>>
>>>> usb_ep_dequeue() can be asynchronous. The dwc3 still has ownership of
>>>> the request until it gives back the request. Freeing the request
>>>> immediately here will cause a problem.
>>>
>>> To confirm my suspicion, can you try this and see if you still get oops?
>>>
>>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>>> index eec8e9a9e3ed..b66eb24ec070 100644
>>> --- a/drivers/usb/dwc3/gadget.c
>>> +++ b/drivers/usb/dwc3/gadget.c
>>> @@ -2031,6 +2031,7 @@ static int dwc3_gadget_ep_dequeue(struct usb_ep
>>> *ep,
>>>                           list_for_each_entry_safe(r, t,
>>> &dep->started_list, list)
>>>                                   dwc3_gadget_move_cancelled_request(r);
>>>    +
>>> dwc3_gadget_ep_cleanup_cancelled_requests(dep);
>>>                           goto out;
>>>                   }
>>>           }
>>>
>>>
>>> This will make usb_ep_dequeue() synchronous. (Note that this is not
>>> tested).
>>
>> Unfortunately, it doesn't work. The trace changes to:
>> root@edison:~# [  104.418264] BUG: kernel NULL pointer dereference,
>> address: 0000000000000000
>> [  104.425227] #PF: supervisor instruction fetch in kernel mode
>> [  104.430877] #PF: error_code(0x0010) - not-present page
>> [  104.436007] PGD 0 P4D 0
>> [  104.438547] Oops: 0010 [#1] SMP PTI
>> [  104.442039] CPU: 1 PID: 605 Comm: irq/15-dwc3 Not tainted
>> 5.9.0-edison-acpi-standard #1
>> [  104.450027] Hardware name: Intel Corporation Merrifield/BODEGA BAY,
>> BIOS 542 2015.01.21:18.19.48
>> [  104.458802] RIP: 0010:0x0
>> [  104.461425] Code: Bad RIP value.
>> [  104.464649] RSP: 0018:ffffae584034fbf8 EFLAGS: 00010046
>> [  104.469870] RAX: 0000000000000000 RBX: ffff8c198608a028 RCX:
>> ffff8c19bb87fa00
>> [  104.476993] RDX: 00000000ffffff94 RSI: ffff8c19bafa54e0 RDI:
>> ffff8c198609ee00
>> [  104.484118] RBP: ffff8c19bafa54e0 R08: 0000000000000046 R09:
>> 0000000000000238
>> [  104.491241] R10: 000000000000002c R11: ffff8c19bcf62490 R12:
>> ffff8c198609ee00
>> [  104.498366] R13: ffff8c198608a028 R14: 0000000000000002 R15:
>> ffff8c19bb8ff000
>> [  104.505493] FS:  0000000000000000(0000) GS:ffff8c19be300000(0000)
>> knlGS:0000000000000000
>> [  104.513572] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> [  104.519309] CR2: ffffffffffffffd6 CR3: 000000002e80a000 CR4:
>> 00000000001006e0
>> [  104.526432] Call Trace:
>> [  104.528892]  dwc3_gadget_giveback+0xbf/0x120
>> [  104.533169]  __dwc3_gadget_ep_disable+0xc5/0x250
>> [  104.537789]  dwc3_gadget_ep_disable+0x3d/0xd0
>> [  104.542149]  usb_ep_disable+0x1d/0x80
>> [  104.545823]  u_audio_stop_capture+0x87/0x9a [u_audio]
>> [  104.550880]  afunc_set_alt+0x73/0x80 [usb_f_uac2]
>> [  104.555594]  composite_setup+0x20f/0x1b20 [libcomposite]
>> [  104.560912]  ? configfs_composite_setup+0x6b/0x90 [libcomposite]
>> [  104.566921]  configfs_composite_setup+0x6b/0x90 [libcomposite]
>> [  104.572752]  dwc3_ep0_delegate_req+0x24/0x40
>> [  104.577022]  dwc3_ep0_interrupt+0x40a/0x9d8
>> [  104.581205]  dwc3_thread_interrupt+0x880/0xf70
>>
> 
> Oops, looks like I can't make it synchronous this way. Can you try
> Jack's change to the u_audio.c instead?

Oops indeed goes away with Jack's change, but usb connection goes 
up/down continuously, meaning: my host sees usb network and audio device 
appearing / disappearing.

mass_storage device does not appear all.

Host:
21-10-2020 22:36	kernel	sd 7:0:0:0: [sdd] tag#0 device offline or changed
21-10-2020 22:36	kernel	blk_update_request: I/O error, dev sdd, sector 0 
op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
21-10-2020 22:36	kernel	Buffer I/O error on dev sdd, logical block 0, 
async page read

And on edison:
Oct 21 22:37:37 edison kernel: IPv6: ADDRCONF(NETDEV_CHANGE): usb0: link 
becomes ready
Oct 21 22:37:37 edison kernel[499]: [  436.595952] IPv6: 
ADDRCONF(NETDEV_CHANGE): usb0: link b>
Oct 21 22:37:37 edison systemd-networkd[521]: usb0: Gained carrier
Oct 21 22:37:38 edison systemd-networkd[521]: usb0: Gained IPv6LL
Oct 21 22:38:07 edison systemd-networkd[521]: usb0: Lost carrier
Oct 21 22:38:07 edison systemd-journald[435]: Forwarding to syslog 
missed 4 messages.


> Thanks,
> Thinh
>