linux-kernel - Re: [PATCH 4/6] dvb/dvb-usb: prepare for FIRMWARE_NAME

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Date:	Tue, 26 May 2009 14:44:45 -0400
From:	Michael Krufky <mkrufky@...nellabs.com>
To:	Samuel Ortiz <sameo@...ux.intel.com>
Cc:	linux-kernel <linux-kernel@...r.kernel.org>,
	Greg Kroah-Hartmann <greg@...ah.com>,
	Mauro Carvalho Chehab <mchehab@...radead.org>,
	Kay Sievers <kay.sievers@...y.org>,
	linux-media <linux-media@...r.kernel.org>
Subject: Re: [PATCH 4/6] dvb/dvb-usb: prepare for FIRMWARE_NAME_MAX removal

On Tue, May 26, 2009 at 2:42 PM, Samuel Ortiz <sameo@...ux.intel.com> wrote:
> On Tue, May 26, 2009 at 02:32:45PM -0400, Michael Krufky wrote:
>> On Tue, May 26, 2009 at 1:40 PM, Samuel Ortiz <sameo@...ux.intel.com> wrote:
>> > From: Samuel Ortiz <sameo@...ux.intel.com>
>> > To: Mauro Carvalho Chehab <mchehab@...radead.org>
>> >
>> > We're going to remove the FIRMWARE_NAME_MAX definition in order to avoid any
>> > firmware name length restriction.
>> > This patch changes the dvb_usb_device_properties firmware field accordingly.
>> >
>> > Signed-off-by: Samuel Ortiz <sameo@...ux.intel.com>
>> >
>> > ---
>> >  drivers/media/dvb/dvb-usb/dvb-usb.h |    2 +-
>> >  1 file changed, 1 insertion(+), 1 deletion(-)
>> >
>> > Index: iwm-2.6/drivers/media/dvb/dvb-usb/dvb-usb.h
>> > ===================================================================
>> > --- iwm-2.6.orig/drivers/media/dvb/dvb-usb/dvb-usb.h    2009-05-26 17:24:36.000000000 +0200
>> > +++ iwm-2.6/drivers/media/dvb/dvb-usb/dvb-usb.h 2009-05-26 17:25:19.000000000 +0200
>> > @@ -196,7 +196,7 @@ struct dvb_usb_device_properties {
>> >  #define CYPRESS_FX2     3
>> >        int        usb_ctrl;
>> >        int        (*download_firmware) (struct usb_device *, const struct firmware *);
>> > -       const char firmware[FIRMWARE_NAME_MAX];
>> > +       const char *firmware;
>> >        int        no_reconnect;
>> >
>> >        int size_of_priv;
>> >
>> > --
>> > Intel Open Source Technology Centre
>> > http://oss.intel.com/
>> > --
>> > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
>> > the body of a message to majordomo@...r.kernel.org
>> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
>> > Please read the FAQ at  http://www.tux.org/lkml/
>> >
>>
>> Samuel,
>>
>> Your patch makes the following change:
>>
>> -       const char firmware[FIRMWARE_NAME_MAX];
>> +       const char *firmware;
>>
>> Before your change, struct dvb_usb_device_properties actually contains
>> memory allocated for the firmware filename.  After your change, this
>> is nothing but a pointer.
>>
>> This will cause an OOPS.
> No, not if it's correctly initialized, as it seems to be for all the
> dvb_usb_device_properties users right now.
> Typically, you'd initialize your dvb_usb_device_properties like this:
>
> static struct dvb_usb_device_properties a800_properties = {
>        .caps = DVB_USB_IS_AN_I2C_ADAPTER,
>
>        .usb_ctrl = CYPRESS_FX2,
>        .firmware = "dvb-usb-avertv-a800-02.fw",
> [...]
>
> And that's fine.

You're right -- there is nothing wrong with the change -- my bad.

I traced though the code after posting that last mail.  It looked
risky when I just looked at the patch, but in the end this is actually
cleaner and much better.

Sorry for the noise.

Acked /
Reviewed-by: Michael Krufky <mkrufky@...nellabs.com>
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