linux-kernel - Re: [PATCH v5 4/7] usb: gadget: f_midi: fix leak on failed to enqueue out requests

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Message-id: <56459FCF.8090409@samsung.com>
Date:	Fri, 13 Nov 2015 09:31:11 +0100
From:	Robert Baldyga <r.baldyga@...sung.com>
To:	"Felipe F. Tonello" <eu@...ipetonello.com>,
	linux-usb@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Felipe Balbi <balbi@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Clemens Ladisch <clemens@...isch.de>
Subject: Re: [PATCH v5 4/7] usb: gadget: f_midi: fix leak on failed to enqueue
 out requests

Hi Felipe,

On 11/10/2015 06:52 PM, Felipe F. Tonello wrote:
> This patch fixes a memory leak that occurs when an endpoint fails to enqueue
> the request. If that happens the complete function will never be called, thus
> never freeing the request.
> 
> Signed-off-by: Felipe F. Tonello <eu@...ipetonello.com>
> ---
>  drivers/usb/gadget/function/f_midi.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/usb/gadget/function/f_midi.c b/drivers/usb/gadget/function/f_midi.c
> index f36db2d..76ea53c 100644
> --- a/drivers/usb/gadget/function/f_midi.c
> +++ b/drivers/usb/gadget/function/f_midi.c
> @@ -345,6 +345,7 @@ static int f_midi_set_alt(struct usb_function *f, unsigned intf, unsigned alt)
>  		if (err) {
>  			ERROR(midi, "%s queue req: %d\n",
>  				    midi->out_ep->name, err);
> +			free_ep_req(midi->out_ep, req);
>  		}
>  	}
>  
> 

There is one more thing I haven't noticed before. We can have situation
when all requests were allocated successfully, but their allocation
failed. What we get then is set_alt() returning 0, while no request is
allocated, hence the function is, in fact, inactive.

Best regards,
Robert
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