linux-kernel - Re: [PATCH 03/23] usb: gadget: f_sourcesink: free requests in sourcesink

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Message-id: <564A07A7.2030407@samsung.com>
Date:	Mon, 16 Nov 2015 17:43:19 +0100
From:	Krzysztof Opasiak <k.opasiak@...sung.com>
To:	Peter Chen <peter.chen@...escale.com>
Cc:	Robert Baldyga <r.baldyga@...sung.com>, balbi@...com,
	gregkh@...uxfoundation.org, andrzej.p@...sung.com,
	m.szyprowski@...sung.com, b.zolnierkie@...sung.com,
	linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 03/23] usb: gadget: f_sourcesink: free requests in
 sourcesink_disable()

Hi,

On 11/10/2015 03:02 AM, Peter Chen wrote:
> On Fri, Nov 06, 2015 at 10:58:39AM +0100, Krzysztof Opasiak wrote:
>>
>>
>> On 11/06/2015 10:48 AM, Peter Chen wrote:
>>> On Fri, Nov 06, 2015 at 09:50:11AM +0100, Robert Baldyga wrote:
>>>> On 11/06/2015 09:15 AM, Peter Chen wrote:
>>>>> On Tue, Nov 03, 2015 at 01:53:42PM +0100, Robert Baldyga wrote:
>>>>>> USB requests in SourceSink function are allocated in sourcesink_get_alt()
>>>>>> function, so we prefer to free them rather in sourcesink_disable() than
>>>>>> in source_sink_complete() when request is completed with error. It provides
>>>>>> better symetry in resource management and improves code readability.
>>>>>>
>>>>>> Signed-off-by: Robert Baldyga <r.baldyga@...sung.com>
>>>>>> ---
>>>>>>   drivers/usb/gadget/function/f_sourcesink.c | 33 +++++++++++++++++++++++++++---
>>>>>>   1 file changed, 30 insertions(+), 3 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/usb/gadget/function/f_sourcesink.c b/drivers/usb/gadget/function/f_sourcesink.c
>>>>>> index a8b68c6..d8f5f56 100644
>>>>>> --- a/drivers/usb/gadget/function/f_sourcesink.c
>>>>>> +++ b/drivers/usb/gadget/function/f_sourcesink.c
>>>>>> @@ -22,6 +22,8 @@
>>>>>>   #include "g_zero.h"
>>>>>>   #include "u_f.h"
>>>>>>
>>>>>> +#define REQ_CNT	8
>>>>>> +
>>>>>
>>>>> It would be buffer if we can have module parameter for this like
>>>>> qlen at f_loopback.
>>>>>> @@ -561,7 +568,6 @@ static void source_sink_complete(struct usb_ep *ep, struct usb_request *req)
>>>>>>   				req->actual, req->length);
>>>>>>   		if (ep == ss->out_ep)
>>>>>>   			check_read_data(ss, req);
>>>>>> -		free_ep_req(ep, req);
>>>>>
>>>>> I find the current code may cause memory leak, since above code
>>>>> is only called one time.
>>>>>
>>>>
>>>> I don't see what you mean. Can you explain a bit more in which situation
>>>> can memory leak take place?
>>>
>>> Oh, sorry, I have not seen there is a "break;" at the source_sink_start_ep for
>>> none-iso endpoint, so, I am wrong, no memory leak here.
>>>
>>> I have tried changing bulk for 8 requests, the performance improves
>>> greatly, but still a little problem for OUT,  I will see what's the matter.
>>> Besides, it will be better we can have a qlen parameters like f_loopback,
>>> in that case, we can improve the performance for gadget, and get the best performance
>>> when testing with usbtest, I will do it later.
>>>
>>
>> Moreover, I would suggest to add qlen and iso_qlen params not only
>> qlen as even now we are using different qlen for bulk and iso.
>>
>
> Krzysztof, would you know why we have different qlen for bulk and iso now?
>

Well, in my opinion iso and bulk use different buf sizes and simply 
different number of requests is needed to saturate the bandwidth.

-- 
Krzysztof Opasiak
Samsung R&D Institute Poland
Samsung Electronics
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