linux-kernel - Re: [PATCH 05/26] usb: gadget: f_ecm: eliminate abuse of ep->driver data

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Message-id: <55F83D36.7090208@samsung.com>
Date:	Tue, 15 Sep 2015 17:45:58 +0200
From:	Krzysztof Opasiak <k.opasiak@...sung.com>
To:	Robert Baldyga <r.baldyga@...sung.com>, balbi@...com
Cc:	gregkh@...uxfoundation.org, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org, b.zolnierkie@...sung.com,
	m.szyprowski@...sung.com, andrzej.p@...sung.com
Subject: Re: [PATCH 05/26] usb: gadget: f_ecm: eliminate abuse of ep->driver
 data



On 09/15/2015 04:26 PM, Robert Baldyga wrote:
> Since ep->driver_data is not used for endpoint claiming, neither for
> enabled/disabled state storing, we can reduce number of places where
> we read or modify it's value, as now it has no particular meaning for
> function or framework logic.
>
> In case of f_ecm, ep->driver_data was used only for endpoint claiming
> and marking endpoints as enabled, so we can simplify code by reducing
> it.
>
> Signed-off-by: Robert Baldyga <r.baldyga@...sung.com>

( ... )

>
> @@ -820,14 +811,6 @@ fail:
>   		usb_ep_free_request(ecm->notify, ecm->notify_req);
>   	}
>
> -	/* we might as well release our claims on endpoints */
> -	if (ecm->notify)
> -		ecm->notify->driver_data = NULL;
> -	if (ecm->port.out_ep)
> -		ecm->port.out_ep->driver_data = NULL;
> -	if (ecm->port.in_ep)
> -		ecm->port.in_ep->driver_data = NULL;
> -
>   	ERROR(cdev, "%s: can't bind, err %d\n", f->name, status);
>
>   	return status;
>

You have done this in almost all functions but personally I'm really 
concern about this change.

By convention function should free all allocated resources when exiting 
with non 0 code. Endpoints are some kind of resources, they are 
"allocated" using usb_ep_autoconfig() and if you are not going to use 
them because error occurred you should free the using 
usb_ep_autoconfig_release(). Moreover, you have done this in source sink 
function so why not do this in all other?


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