Re: g_audio breaks with dwc3

[Felipe Balbi <balbi@kernel.org>]

Hi,

Roger Quadros <rogerq@ti.com> writes:
> Felipe,
>
> On 30/10/2019 13:26, Felipe Balbi wrote:
>> 
>> Hi,
>> 
>> Roger Quadros <rogerq@ti.com> writes:
>>>>>>       irq/170-dwc3-1240  [000] d...    85.450564: dwc3_gadget_giveback: ep1out: req ee75d6ac length 0/256 zsI ==> -108
>>>>>>       irq/170-dwc3-1240  [000] d...    85.450566: dwc3_gadget_giveback: ep1out: req c26c10a3 length 0/256 zsI ==> -108
>>>>>>       irq/170-dwc3-1240  [000] d...    85.450567: dwc3_gadget_giveback: : req d4301893 length 0/0 zsI ==> 0
>>>>>
>>>>> Giveback happens on above two reqs after they are already freed. Could
>>>>> it be due to f_uac2 / u_audio.c performing usb_ep_free_request()
>>>>> immediately after usb_ep_dequeue() without waiting for completion?
>>>>
>>>> this could be a race condition. Add a trace_printk() at the cancelation,
>>>> see if the request is moved to cancelled list.
>>>>
>>>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>>>> index 86dc1db788a9..affc2f7a929d 100644
>>>> --- a/drivers/usb/dwc3/gadget.c
>>>> +++ b/drivers/usb/dwc3/gadget.c
>>>> @@ -1513,6 +1513,7 @@ static void dwc3_gadget_ep_cleanup_cancelled_requests(struct dwc3_ep *dep)
>>>>    	struct dwc3_request		*tmp;
>>>>    
>>>>    	list_for_each_entry_safe(req, tmp, &dep->cancelled_list, list) {
>>>> +		trace_printk("---> completing cancellation of req %p\n", req);
>>>>    		dwc3_gadget_ep_skip_trbs(dep, req);
>>>>    		dwc3_gadget_giveback(dep, req, -ECONNRESET);
>>>>    	}
>>>> @@ -1551,6 +1552,7 @@ static int dwc3_gadget_ep_dequeue(struct usb_ep *ep,
>>>>    			if (!r->trb)
>>>>    				goto out0;
>>>>    
>>>> +			trace_printk("---> req %p moved to cancelled\n", req);
>>>>    			dwc3_gadget_move_cancelled_request(req);
>>>>    			if (dep->flags & DWC3_EP_TRANSFER_STARTED)
>>>>    				goto out0;
>>>>
>>>>
>>>
>>> Below is trace with above debug patch applied.
>> 
>> Did it fail the same way? It doesn't look like in the trace.
>> 
>> Does this help?
>> 
>> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
>> index 86dc1db788a9..a9aba716bf80 100644
>> --- a/drivers/usb/dwc3/gadget.c
>> +++ b/drivers/usb/dwc3/gadget.c
>> @@ -707,6 +707,12 @@ static void dwc3_remove_requests(struct dwc3 *dwc, struct dwc3_ep *dep)
>>   
>>   		dwc3_gadget_giveback(dep, req, -ESHUTDOWN);
>>   	}
>> +
>> +	while (!list_empty(&dep->cancelled_list)) {
>> +		req = next_request(&dep->cancelled_list);
>> +
>> +		dwc3_gadget_giveback(dep, req, -ESHUTDOWN);
>> +	}
>>   }
>>   
>>   /**
>> 
>
> Yes, this fixes the issue.
> I'm able to use aplay/arecord as well. Thanks!

Great, I'll send as a fix

-- 
balbi