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Date:   Tue, 31 Oct 2023 10:53:30 +0100
From:   Paul Kocialkowski <paul.kocialkowski@bootlin.com>
To:     Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Cc:     Mehdi Djait <mehdi.djait@bootlin.com>, mchehab@kernel.org,
        heiko@sntech.de, hverkuil-cisco@xs4all.nl,
        krzysztof.kozlowski+dt@linaro.org, robh+dt@kernel.org,
        conor+dt@kernel.org, linux-media@vger.kernel.org,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        thomas.petazzoni@bootlin.com, alexandre.belloni@bootlin.com,
        maxime.chevallier@bootlin.com, michael.riesch@wolfvision.net
Subject: Re: [PATCH v9 2/3] media: rockchip: Add a driver for Rockchip's
 camera interface
Message-ID: <ZUDOmgmkIifE2w87@aptenodytes>
References: <cover.1698666612.git.mehdi.djait@bootlin.com>
 <f7367726eb077d43446c83591ecbf9acbc77ef5f.1698666612.git.mehdi.djait@bootlin.com>
 <ad346052-ec62-4d68-903e-fccd7ad989bd@wanadoo.fr>
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 <79231ec3-8da1-4c73-8f5b-efa445e6c35d@wanadoo.fr>
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Hi,

On Tue 31 Oct 23, 10:46, Christophe JAILLET wrote:
> Le 31/10/2023 =C3=A0 10:33, Mehdi Djait a =C3=A9crit=C2=A0:
> > Hello Christophe,
> >=20
> > On Mon, Oct 30, 2023 at 01:47:17PM +0100, Christophe JAILLET wrote:
> > > > +	/* Create & register platform subdev. */
> > > > +	ret =3D cif_register_stream_vdev(cif_dev);
> > > > +	if (ret < 0)
> > > > +		goto err_unreg_media_dev;
> > > > +
> > > > +	ret =3D cif_subdev_notifier(cif_dev);
> > > > +	if (ret < 0) {
> > > > +		v4l2_err(&cif_dev->v4l2_dev,
> > > > +			 "Failed to register subdev notifier(%d)\n", ret);
> > > > +		cif_unregister_stream_vdev(cif_dev);
> > > > +		goto err_unreg_media_dev;
> > >=20
> > > Should there be another label with cif_unregister_stream_vdev(cif_dev=
); if
> > > an error occurs here?
> > >=20
> > > CJ
> >=20
> > cif_subdev_notifier() is the last function call in the probe with error
> > handling. So it will undo the last successful register:
> > cif_register_stream_vdev and use the goto to unregister the rest.
>=20
> Ah, I didn't see the cif_unregister_stream_vdev() call here.
> Sorry for the noise.
>=20
> >=20
> > I can add a label err_unreg_stream_vdev but it will be only used in the
> > error handling of cif_subdev_notifier() and I don't see the benefit.
>=20
> The main benefit is to be more consistent in the way the error path is
> written, and to be more future proof.

Indeed the fact that there is only a single user of the label is not a reas=
on
to avoid the label. As soon as you need to use labels/gotos for error handl=
ing,
you should do it for all steps involved and avoid mixing unregistration in =
the
error-checking condition and using a previous label.

Cheers,

Paul

>=20
> CJ
> >=20
> > --
> > Kind Regards
> > Mehdi Djait
> >=20
> > > > +	}
> > > > +
> > > > +	cif_set_default_format(cif_dev);
> > > > +	pm_runtime_enable(&pdev->dev);
> > > > +
> > > > +	return 0;
> > > > +
> > > > +err_unreg_media_dev:
> > > > +	media_device_unregister(&cif_dev->media_dev);
> > > > +err_unreg_v4l2_dev:
> > > > +	v4l2_device_unregister(&cif_dev->v4l2_dev);
> > > > +	return ret;
> > > > +}
> >=20
>=20

--=20
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

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