Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Mon, 5 Oct 2020 11:51:32 +0200
From:   Thierry Reding <thierry.reding@gmail.com>
To:     Dmitry Osipenko <digetx@gmail.com>
Cc:     Nicolin Chen <nicoleotsuka@gmail.com>, joro@8bytes.org,
        vdumpa@nvidia.com, jonathanh@nvidia.com,
        linux-tegra@vger.kernel.org, iommu@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 2/3] iommu/tegra-smmu: Rework tegra_smmu_probe_device()
Message-ID: <20201005095132.GH425362@ulmo>
References: <20201002060807.32138-1-nicoleotsuka@gmail.com>
 <20201002060807.32138-3-nicoleotsuka@gmail.com>
 <b1a195cf-0127-0531-f6d1-835367511f57@gmail.com>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha256;
        protocol="application/pgp-signature"; boundary="a8sldprk+5E/pDEv"
Content-Disposition: inline
In-Reply-To: <b1a195cf-0127-0531-f6d1-835367511f57@gmail.com>
User-Agent: Mutt/1.14.7 (2020-08-29)
Precedence: bulk


--a8sldprk+5E/pDEv
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

On Fri, Oct 02, 2020 at 05:22:41PM +0300, Dmitry Osipenko wrote:
> 02.10.2020 09:08, Nicolin Chen =D0=BF=D0=B8=D1=88=D0=B5=D1=82:
> >  static int tegra_smmu_of_xlate(struct device *dev,
> >  			       struct of_phandle_args *args)
> >  {
> > +	struct platform_device *iommu_pdev =3D of_find_device_by_node(args->n=
p);
> > +	struct tegra_mc *mc =3D platform_get_drvdata(iommu_pdev);
> >  	u32 id =3D args->args[0];
> > =20
> > +	of_node_put(args->np);
> > +
> > +	if (!mc || !mc->smmu)
> > +		return -EPROBE_DEFER;
>=20
> platform_get_drvdata(NULL) will crash.
>=20
> > +	dev_iommu_priv_set(dev, mc->smmu);
>=20
> I think put_device(mc->dev) is missed here, doesn't it?

Yeah, I think we'd need that here, otherwise we'd be leaking a
reference. Worse, even, mc->dev is the same device that owns the SMMU,
so we're basically incrementing our own reference here and never
releasing it. We also need that put_device(mc->dev) in the error case
above because we already hold the reference there.

Thierry

--a8sldprk+5E/pDEv
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----
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=ny5U
-----END PGP SIGNATURE-----

--a8sldprk+5E/pDEv--