linux-kernel - RE: [PATCH] usb: gadget: udc: atmel: used managed kasprintf

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Message-ID: <87eg03nvuv.fsf@linux.intel.com>
Date:   Mon, 16 Jan 2017 12:27:04 +0200
From:   Felipe Balbi <balbi@...nel.org>
To:     David Laight <David.Laight@...LAB.COM>,
        'Alexandre Belloni' <alexandre.belloni@...e-electrons.com>
Cc:     Nicolas Ferre <nicolas.ferre@...el.com>,
        "linux-arm-kernel\@lists.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-usb\@vger.kernel.org" <linux-usb@...r.kernel.org>
Subject: RE: [PATCH] usb: gadget: udc: atmel: used managed kasprintf


Hi,

David Laight <David.Laight@...LAB.COM> writes:
> From: Alexandre Belloni
>> Sent: 02 December 2016 16:19
>> On 02/12/2016 at 15:59:57 +0000, David Laight wrote :
>> > From: Alexandre Belloni
>> > > Sent: 01 December 2016 10:27
>> > > Use devm_kasprintf instead of simple kasprintf to free the allocated memory
>> > > when needed.
>> >
>> > s/when needed/when the device is freed/
>> >
>> > > Suggested-by: Peter Rosin <peda@...ntia.se>
>> > > Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
>> > > ---
>> > >  drivers/usb/gadget/udc/atmel_usba_udc.c | 3 ++-
>> > >  1 file changed, 2 insertions(+), 1 deletion(-)
>> > >
>> > > diff --git a/drivers/usb/gadget/udc/atmel_usba_udc.c b/drivers/usb/gadget/udc/atmel_usba_udc.c
>> > > index 45bc997d0711..aec72fe8273c 100644
>> > > --- a/drivers/usb/gadget/udc/atmel_usba_udc.c
>> > > +++ b/drivers/usb/gadget/udc/atmel_usba_udc.c
>> > > @@ -1978,7 +1978,8 @@ static struct usba_ep * atmel_udc_of_init(struct platform_device *pdev,
>> > >  			dev_err(&pdev->dev, "of_probe: name error(%d)\n", ret);
>> > >  			goto err;
>> > >  		}
>> > > -		ep->ep.name = kasprintf(GFP_KERNEL, "ep%d", ep->index);
>> > > +		ep->ep.name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "ep%d",
>> > > +					     ep->index);
>> >
>> > Acually why bother mallocing such a small string at all.
>> > The maximum length is 12 bytes even if 'index' are unrestricted.
>> >
>> 
>> IIRC, using statically allocated string is failing somewhere is the USB
>> core but I don't remember all the details.
>
> I can't imagine that changing ep->ep.name from 'char *' to 'char [12]' would
> make any difference.

the actual name is managed by the UDC. Meaning, ep->ep.name should be a
pointer, but it could very well just point to ep->name which would be
char [12].

-- 
balbi

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