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

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Date:	Fri, 06 Nov 2015 10:58:39 +0100
From:	Krzysztof Opasiak <k.opasiak@...sung.com>
To:	Peter Chen <peter.chen@...escale.com>,
	Robert Baldyga <r.baldyga@...sung.com>
Cc:	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()



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.

Best regards,
-- 
Krzysztof Opasiak
Samsung R&D Institute Poland
Samsung Electronics
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