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Message-ID: <Ybop+ZdUQSqGkOxe@kroah.com>
Date: Wed, 15 Dec 2021 18:46:33 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: LKML <linux-kernel@...r.kernel.org>,
Bjorn Helgaas <helgaas@...nel.org>,
Marc Zygnier <maz@...nel.org>,
Alex Williamson <alex.williamson@...hat.com>,
Kevin Tian <kevin.tian@...el.com>,
Jason Gunthorpe <jgg@...dia.com>,
Megha Dey <megha.dey@...el.com>,
Ashok Raj <ashok.raj@...el.com>, linux-pci@...r.kernel.org,
Cedric Le Goater <clg@...d.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Juergen Gross <jgross@...e.com>,
xen-devel@...ts.xenproject.org, Arnd Bergmann <arnd@...db.de>,
Michael Ellerman <mpe@...erman.id.au>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
linuxppc-dev@...ts.ozlabs.org, Stuart Yoder <stuyoder@...il.com>,
Laurentiu Tudor <laurentiu.tudor@....com>,
Nishanth Menon <nm@...com>, Tero Kristo <kristo@...nel.org>,
Santosh Shilimkar <ssantosh@...nel.org>,
linux-arm-kernel@...ts.infradead.org,
Vinod Koul <vkoul@...nel.org>, dmaengine@...r.kernel.org,
Mark Rutland <mark.rutland@....com>,
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Robin Murphy <robin.murphy@....com>,
Joerg Roedel <joro@...tes.org>,
iommu@...ts.linux-foundation.org,
Jassi Brar <jassisinghbrar@...il.com>,
Peter Ujfalusi <peter.ujfalusi@...il.com>,
Sinan Kaya <okaya@...nel.org>
Subject: Re: [patch V4 09-01/35] PCI/MSI: Decouple MSI[-X] disable from
pcim_release()
On Wed, Dec 15, 2021 at 06:16:44PM +0100, Thomas Gleixner wrote:
> The MSI core will introduce runtime allocation of MSI related data. This
> data will be devres managed and has to be set up before enabling
> PCI/MSI[-X]. This would introduce an ordering issue vs. pcim_release().
>
> The setup order is:
>
> pcim_enable_device()
> devres_alloc(pcim_release...);
> ...
> pci_irq_alloc()
> msi_setup_device_data()
> devres_alloc(msi_device_data_release, ...)
>
> and once the device is released these release functions are invoked in the
> opposite order:
>
> msi_device_data_release()
> ...
> pcim_release()
> pci_disable_msi[x]()
>
> which is obviously wrong, because pci_disable_msi[x]() requires the MSI
> data to be available to tear down the MSI[-X] interrupts.
>
> Remove the MSI[-X] teardown from pcim_release() and add an explicit action
> to be installed on the attempt of enabling PCI/MSI[-X].
>
> This allows the MSI core data allocation to be ordered correctly in a
> subsequent step.
>
> Reported-by: Nishanth Menon <nm@...com>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> ---
> V4: New patch
Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
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