linux-kernel - Re: [PATCH 4.4 009/134] PCI/MSI: Stop disabling MSI/MSI-X in pci_device

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Date:   Wed, 4 Apr 2018 17:24:10 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Ben Hutchings <ben.hutchings@...ethink.co.uk>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Prarit Bhargava <prarit@...hat.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        David Arcari <darcari@...hat.com>,
        Myron Stowe <mstowe@...hat.com>,
        Lukas Wunner <lukas@...ner.de>,
        Keith Busch <keith.busch@...el.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: Re: [PATCH 4.4 009/134] PCI/MSI: Stop disabling MSI/MSI-X in
 pci_device_shutdown()

On Thu, Mar 29, 2018 at 04:28:54PM +0100, Ben Hutchings wrote:
> On Mon, 2018-03-19 at 19:04 +0100, Greg Kroah-Hartman wrote:
> > 4.4-stable review patch.  If anyone has any objections, please let me know.
> > 
> > ------------------
> > 
> > From: Prarit Bhargava <prarit@...hat.com>
> > 
> > 
> > [ Upstream commit fda78d7a0ead144f4b2cdb582dcba47911f4952c ]
> [...]
> > The MSI disabling code was added by d52877c7b1af ("pci/irq: let
> > pci_device_shutdown to call pci_msi_shutdown v2") because a driver left MSI
> > enabled and kdump failed because the kexeced kernel wasn't prepared to
> > receive the MSI interrupts.
> > 
> > Subsequent commits 1851617cd2da ("PCI/MSI: Disable MSI at enumeration even
> > if kernel doesn't support MSI")
> 
> This went into 4.2 and hasn't been backported.

To backport that to 3.18.y takes 2 other patches to get it "correct".

> > and  e80e7edc55ba ("PCI/MSI: Initialize MSI capability for all
> > architectures")
> 
> This went into 4.5 and hasn't been backported.

Yeah, but that really isn't needed unless 4d9aac397a5d ("powerpc/PCI:
Disable MSI/MSI-X interrupts at PCI probe time in OF case") is also
there, along with 1851617cd2da.

> So I think 3.18-stable and 4.4-stable will need backports of the later
> changes in order for this to work properly.

I think I'm just going to revert this as no one is complaining about
this issue on 4.4.y and 3.18.y kernels.  Thanks for the review.

greg k-h