Date: Fri, 6 Nov 2015 17:48:45 +0800
From: Peter Chen <peter.chen@freescale.com>
To: Robert Baldyga <r.baldyga@samsung.com>
CC: <balbi@ti.com>, <gregkh@linuxfoundation.org>, <andrzej.p@samsung.com>,
        <m.szyprowski@samsung.com>, <b.zolnierkie@samsung.com>,
        <linux-usb@vger.kernel.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 03/23] usb: gadget: f_sourcesink: free requests in
 sourcesink_disable()
Message-ID: <20151106094844.GA2809@shlinux2>
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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@samsung.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.

Peter

> 
> 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
> >>
> >> --
> >> To unsubscribe from this list: send the line "unsubscribe linux-usb" in
> >> the body of a message to majordomo@vger.kernel.org
> >> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> > 
> 

-- 

Best Regards,
Peter Chen
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