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

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Message-id: <563C69C3.2030102@samsung.com>
Date:	Fri, 06 Nov 2015 09:50:11 +0100
From:	Robert Baldyga <r.baldyga@...sung.com>
To:	Peter Chen <peter.chen@...escale.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 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.
> 
>>  /*
>>   * SOURCE/SINK FUNCTION ... a primary testing vehicle for USB peripheral
>>   * controller drivers.
>> @@ -51,6 +53,11 @@ struct f_sourcesink {
>>  	struct usb_ep		*iso_out_ep;
>>  	int			cur_alt;
>>  
>> +	struct usb_request	*in_req;
>> +	struct usb_request	*out_req;
>> +	struct usb_request	*iso_in_req[REQ_CNT];
>> +	struct usb_request	*iso_out_req[REQ_CNT];
>> +
>>  	unsigned pattern;
>>  	unsigned isoc_interval;
>>  	unsigned isoc_maxpacket;
>> @@ -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?

I've only changed place where requests are freed. Now they are freed in
sourcesink_disable(). The current code is even more memory leak
resistant, because requests will be freed even in case of failure of
usb_ep_queue() in source_sink_complete(), which was not provided so far.

>>  		return;
>>  
>>  	case -EOVERFLOW:		/* buffer overrun on read means that
>> @@ -613,7 +619,7 @@ static int source_sink_start_ep(struct f_sourcesink *ss, bool is_in,
>>  		ep = is_in ? ss->in_ep : ss->out_ep;
>>  	}
>>  
>> -	for (i = 0; i < 8; i++) {
>> +	for (i = 0; i < REQ_CNT; i++) {
>>  		req = ss_alloc_ep_req(ep, size);
>>  		if (!req)
>>  			return -ENOMEM;
>> @@ -635,8 +641,18 @@ static int source_sink_start_ep(struct f_sourcesink *ss, bool is_in,
>>  			free_ep_req(ep, req);
>>  		}
>>  
>> -		if (!is_iso)
>> +		if (is_iso) {
>> +			if (is_in)
>> +				ss->iso_in_req[i] = req;
>> +			else
>> +				ss->iso_out_req[i] = req;
>> +		} else {
>> +			if (is_in)
>> +				ss->in_req = req;
>> +			else
>> +				ss->out_req = req;
> 
> The req will be different for both bulk and iso, why you only
> have array for iso requests?

Because only for iso endpoints there is allocated more than one request.
I don't know why, but I've decided to not change this.

> 
>>  			break;
>> +		}
>>  	}
>>  
>>  	return status;
>> @@ -764,8 +780,19 @@ static int sourcesink_get_alt(struct usb_function *f, unsigned intf)
>>  static void sourcesink_disable(struct usb_function *f)
>>  {
>>  	struct f_sourcesink	*ss = func_to_ss(f);
>> +	int i;
>>  
>>  	disable_source_sink(ss);
>> +
>> +	free_ep_req(ss->in_ep, ss->in_req);
>> +	free_ep_req(ss->out_ep, ss->out_req);
>> +
>> +	if (ss->iso_in_ep) {
>> +		for (i = 0; i < REQ_CNT; i++) {
>> +			free_ep_req(ss->iso_in_ep, ss->iso_in_req[i]);
>> +			free_ep_req(ss->iso_out_ep, ss->iso_out_req[i]);
>> +		}
>> +	}
>>  }
>>  
>>  /*-------------------------------------------------------------------------*/
>> -- 
>> 1.9.1
>>
>> --
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> 

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