Message-ID: <50191509.8030404@pengutronix.de>
Date: Wed, 01 Aug 2012 13:37:45 +0200
From: Marc Kleine-Budde <mkl@pengutronix.de>
Organization: Pengutronix e.K.
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120713 Thunderbird/14.0
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To: Fabio Baltieri <fabio.baltieri@gmail.com>
CC: linux-can@vger.kernel.org, linux-kernel@vger.kernel.org,
        Oliver Hartkopp <socketcan@hartkopp.net>,
        Wolfgang Grandegger <wg@grandegger.com>
Subject: Re: [PATCH can-next v4] can: add tx/rx LED trigger support
References: <5017C8E4.4020003@pengutronix.de> <1343772338-1526-1-git-send-email-fabio.baltieri@gmail.com> <5018F8B3.6080404@pengutronix.de> <20120801103032.GA1385@gmail.com>
In-Reply-To: <20120801103032.GA1385@gmail.com>
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On 08/01/2012 12:30 PM, Fabio Baltieri wrote:
[...]
>>> +void can_led_init(struct net_device *netdev)
>>> +{
>>> +	struct can_priv *priv =3D netdev_priv(netdev);
>>> +	void *res;
>>> +
>>> +	res =3D devres_alloc(can_led_release, 0, GFP_KERNEL);
>>                                             ^
>> I'm not really sure if this is working. For example, pinctrl [1]
>> allocates a double pointer here. The res pointer here and in
>> can_led_release simply points to invalid memory. But as long as you
>> don't dereference it, it should work.
>>
>> [1] http://lxr.free-electrons.com/source/drivers/pinctrl/core.c#L862
>=20
> Actually that's also used by libata-core (not in lxr yet) and dma-mappi=
ng:
>=20
> http://lxr.free-electrons.com/source/drivers/base/dma-mapping.c#L193
>=20
> actually, res should point at the end of some internal devres structure=
,
> and is only used as return value in this case.
>=20
> Of course, in this case the release function can only use the struct
> device pointer.
>=20
> I've run some fail test and ftraced the whole thing and it seems to wor=
k
> pretty good!  I'll send a v5 with the rename later.

Thanks for checking. I just noticed, the pinctrl usecase is a bit differe=
nt.

Marc
--=20
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |


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