Re: g_audio breaks with dwc3

[Felipe Balbi <balbi@kernel.org>]

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);
+	}
 }
 
 /**

-- 
balbi