Date: Tue, 7 Mar 2017 05:52:36 +0100
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Doug Ledford <dledford@redhat.com>,
        Sebastian Ott <sebott@linux.vnet.ibm.com>,
        Parav Pandit <parav@mellanox.com>, linux-rdma@vger.kernel.org,
        linux-kernel@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        David Woodhouse <dwmw2@infradead.org>,
        "H . Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@redhat.com>,
        Russell King <linux@armlinux.org.uk>
Subject: Re: [PATCH 1/2] device: Stop requiring that struct device is
 embedded in struct pci_dev
Message-ID: <20170307045236.GC3913@kroah.com>
References: <20170307003549.3872-1-bart.vanassche@sandisk.com>
 <20170307003549.3872-2-bart.vanassche@sandisk.com>
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On Mon, Mar 06, 2017 at 04:35:48PM -0800, Bart Van Assche wrote:
> The dma mapping operations of several architectures and also of
> several I/O MMU implementations need to translate a struct
> device pointer into a struct pci_dev pointer. This translation
> is performed by to_pci_dev(). That macro assumes that struct
> device is embedded in struct pci_dev. However, that is not the
> case for the device structure in struct ib_device.

Then don't blindly cast it backwards!  Fix that up, an ib device should
have access to the dma structures that the PCI device it depends on has.
If not, you need to set that up properly in the IB core, don't mess with
the driver core for this at all.

Somehow all other subsystems work just fine, don't instantly think that
the driver core needs to bend to the will of the IB code, because you
are somehow "special".  Hint, you aren't :)

greg k-h