linux-kernel - Re: [PATCH v4 02/16] ACPI/IORT: Remove direct access of dev->iommu

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Message-ID: <20200327084546.GA4083132@myrica>
Date:   Fri, 27 Mar 2020 09:45:46 +0100
From:   Jean-Philippe Brucker <jean-philippe@...aro.org>
To:     Hanjun Guo <guohanjun@...wei.com>
Cc:     Joerg Roedel <joro@...tes.org>, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-mediatek@...ts.infradead.org,
        Sudeep Holla <sudeep.holla@....com>,
        Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Joerg Roedel <jroedel@...e.de>
Subject: Re: [PATCH v4 02/16] ACPI/IORT: Remove direct access of
 dev->iommu_fwspec

On Fri, Mar 27, 2020 at 11:30:53AM +0800, Hanjun Guo wrote:
> On 2020/3/26 23:08, Joerg Roedel wrote:
> > From: Joerg Roedel <jroedel@...e.de>
> > 
> > Use the accessor functions instead of directly dereferencing
> > dev->iommu_fwspec.
> > 
> > Tested-by: Hanjun Guo <guohanjun@...wei.com>
> > Reviewed-by: Jean-Philippe Brucker <jean-philippe@...aro.org>
> > Signed-off-by: Joerg Roedel <jroedel@...e.de>
> > ---
> >  drivers/acpi/arm64/iort.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> > index ed3d2d1a7ae9..7d04424189df 100644
> > --- a/drivers/acpi/arm64/iort.c
> > +++ b/drivers/acpi/arm64/iort.c
> > @@ -1015,6 +1015,7 @@ const struct iommu_ops *iort_iommu_configure(struct device *dev)
> >  		return ops;
> >  
> >  	if (dev_is_pci(dev)) {
> > +		struct iommu_fwspec *fwspec;
> >  		struct pci_bus *bus = to_pci_dev(dev)->bus;
> >  		struct iort_pci_alias_info info = { .dev = dev };
> >  
> > @@ -1027,8 +1028,9 @@ const struct iommu_ops *iort_iommu_configure(struct device *dev)
> >  		err = pci_for_each_dma_alias(to_pci_dev(dev),
> >  					     iort_pci_iommu_init, &info);
> 
> ...
> 
> >  
> > -		if (!err && iort_pci_rc_supports_ats(node))
> > -			dev->iommu_fwspec->flags |= IOMMU_FWSPEC_PCI_RC_ATS;
> > +		fwspec = dev_iommu_fwspec_get(dev);
> > +		if (fwspec && iort_pci_rc_supports_ats(node))
> 
> Should we check !err as well?

No need, the check should have been on fwspec from the beginning. Checking
err was just a lazy shortcut on my part, as we're really just making sure
that we can dereference fwspec->flags here.

Thanks,
Jean

> 
> Thanks
> Hanjun
> 
> > +			fwspec->flags |= IOMMU_FWSPEC_PCI_RC_ATS;
> >  	} else {
> >  		int i = 0;
> >  
> > 
>