From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jerome Glisse <jglisse@redhat.com>
Subject: Re: [RFC PATCH 1/5] pci/p2p: add a function to test peer to peer
 capability
Date: Tue, 29 Jan 2019 14:53:02 -0500
Message-ID: <20190129195302.GI3176@redhat.com>
References: <20190129174728.6430-1-jglisse@redhat.com>
 <20190129174728.6430-2-jglisse@redhat.com>
 <f66ba584-9c4a-f6cd-c647-9b32a93be807@deltatee.com>
 <20190129194426.GB32069@kroah.com>
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To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Logan Gunthorpe <logang@deltatee.com>, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Rafael J . Wysocki" <rafael@kernel.org>, Bjorn Helgaas <bhelgaas@google.com>, Christian Koenig <christian.koenig@amd.com>, Felix Kuehling <Felix.Kuehling@amd.com>, Jason Gunthorpe <jgg@mellanox.com>, linux-pci@vger.kernel.org, dri-devel@lists.freedesktop.org, Christoph Hellwig <hch@lst.de>, Marek Szyprowski <m.szyprowski@samsung.com>, Robin Murphy <robin.murphy@arm.com>, Joerg Roedel <jroedel@suse.de>, iommu@lists.linux-foundation.org
List-Id: iommu@lists.linux-foundation.org

On Tue, Jan 29, 2019 at 08:44:26PM +0100, Greg Kroah-Hartman wrote:
> On Tue, Jan 29, 2019 at 11:24:09AM -0700, Logan Gunthorpe wrote:
> > 
> > 
> > On 2019-01-29 10:47 a.m., jglisse@redhat.com wrote:
> > > +bool pci_test_p2p(struct device *devA, struct device *devB)
> > > +{
> > > +	struct pci_dev *pciA, *pciB;
> > > +	bool ret;
> > > +	int tmp;
> > > +
> > > +	/*
> > > +	 * For now we only support PCIE peer to peer but other inter-connect
> > > +	 * can be added.
> > > +	 */
> > > +	pciA = find_parent_pci_dev(devA);
> > > +	pciB = find_parent_pci_dev(devB);
> > > +	if (pciA == NULL || pciB == NULL) {
> > > +		ret = false;
> > > +		goto out;
> > > +	}
> > > +
> > > +	tmp = upstream_bridge_distance(pciA, pciB, NULL);
> > > +	ret = tmp < 0 ? false : true;
> > > +
> > > +out:
> > > +	pci_dev_put(pciB);
> > > +	pci_dev_put(pciA);
> > > +	return false;
> > > +}
> > > +EXPORT_SYMBOL_GPL(pci_test_p2p);
> > 
> > This function only ever returns false....
> 
> I guess it was nevr actually tested :(
> 
> I feel really worried about passing random 'struct device' pointers into
> the PCI layer.  Are we _sure_ it can handle this properly?
> 

Oh yes i fixed it on the test rig and forgot to patch
my local git tree. My bad.

Cheers,
Jérôme