linux-kernel - Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute

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Date:   Fri, 15 Dec 2017 13:52:14 -0600
From:   Govinda Tatti <Govinda.Tatti@...cle.COM>
To:     Jan Beulich <JBeulich@...e.com>
Cc:     roger.pau@...rix.com, bhelgaas@...gle.com,
        xen-devel@...ts.xenproject.org, boris.ostrovsky@...cle.COM,
        konrad.wilk@...cle.COM, Juergen Gross <jgross@...e.com>,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with
 'reset' SysFS attribute

Jan,

One quick update on pcie_flr() specific implementation. Please see below.
>>> +static int pcistub_device_reset(struct pci_dev *dev)
>>> +{
>>> +	struct xen_pcibk_dev_data *dev_data;
>>> +	bool slot = false, bus = false;
>>> +	struct pcistub_args arg = {};
>>> +
>>> +	if (!dev)
>>> +		return -EINVAL;
>>> +
>>> +	dev_dbg(&dev->dev, "[%s]\n", __func__);
>>> +
>>> +	/* First check and try FLR */
>>> +	if (pcie_has_flr(dev)) {
>>> +		dev_dbg(&dev->dev, "resetting %s device using FLR\n",
>>> +			pci_name(dev));
>>> +		pcie_flr(dev);
>> The lack of error check here puzzled me, but I see the function
>> indeed returns void right now. I think the prereq patch should
>> change this along with exporting the function - you really don't
>> want the device to be handed to a guest when the FLR timed
>> out.
> We will change pcie_flr() to return error code. I will make this change
> in the next version of this patch.
I exchanged some emails with Bjorn/Christoph and it looks like Christoph
as some planto restructure pcie flr specific functions but I don't know
the exact time-frame. For now,I am planning to use existing pcie_flr()
after checking FLR capability. We will switchto revised pcie_flr() once
it is available.

I hope you are fine with this approach. Please let me know. Thanks.

Cheers
GOVINDA