Patch "PCI/MSI: Stop disabling MSI/MSI-X in pci_device_shutdown()" has been added to the 4.4-stable tree

Patch "PCI/MSI: Stop disabling MSI/MSI-X in pci_device_shutdown()" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    PCI/MSI: Stop disabling MSI/MSI-X in pci_device_shutdown()

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     pci-msi-stop-disabling-msi-msi-x-in-pci_device_shutdown.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Mon Mar 19 09:58:12 CET 2018
From: Prarit Bhargava <prarit@redhat.com>
Date: Thu, 26 Jan 2017 14:07:47 -0500
Subject: PCI/MSI: Stop disabling MSI/MSI-X in pci_device_shutdown()

From: Prarit Bhargava <prarit@redhat.com>


[ Upstream commit fda78d7a0ead144f4b2cdb582dcba47911f4952c ]

The pci_bus_type .shutdown method, pci_device_shutdown(), is called from
device_shutdown() in the kernel restart and shutdown paths.

Previously, pci_device_shutdown() called pci_msi_shutdown() and
pci_msix_shutdown().  This disables MSI and MSI-X, which causes the device
to fall back to raising interrupts via INTx.  But the driver is still bound
to the device, it doesn't know about this change, and it likely doesn't
have an INTx handler, so these INTx interrupts cause "nobody cared"
warnings like this:

  irq 16: nobody cared (try booting with the "irqpoll" option)
  CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.8.2-1.el7_UNSUPPORTED.x86_64 #1
  Hardware name: Hewlett-Packard HP Z820 Workstation/158B, BIOS J63 v03.90 06/
  ...

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") and  e80e7edc55ba ("PCI/MSI: Initialize MSI
capability for all architectures") changed the kexeced kernel to disable
all MSIs itself so it no longer depends on the crashed kernel to clean up
after itself.

Stop disabling MSI/MSI-X in pci_device_shutdown().  This resolves the
"nobody cared" unhandled IRQ issue above.  It also allows PCI serial
devices, which may rely on the MSI interrupts, to continue outputting
messages during reboot/shutdown.

[bhelgaas: changelog, drop pci_msi_shutdown() and pci_msix_shutdown() calls
altogether]
Fixes: https://bugzilla.kernel.org/show_bug.cgi?id=187351
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Alex Williamson <alex.williamson@redhat.com>
CC: David Arcari <darcari@redhat.com>
CC: Myron Stowe <mstowe@redhat.com>
CC: Lukas Wunner <lukas@wunner.de>
CC: Keith Busch <keith.busch@intel.com>
CC: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/pci/pci-driver.c |    2 --
 1 file changed, 2 deletions(-)

--- a/drivers/pci/pci-driver.c
+++ b/drivers/pci/pci-driver.c
@@ -463,8 +463,6 @@ static void pci_device_shutdown(struct d
 
 	if (drv && drv->shutdown)
 		drv->shutdown(pci_dev);
-	pci_msi_shutdown(pci_dev);
-	pci_msix_shutdown(pci_dev);
 
 #ifdef CONFIG_KEXEC_CORE
 	/*


Patches currently in stable-queue which might be from prarit@redhat.com are

queue-4.4/pci-msi-stop-disabling-msi-msi-x-in-pci_device_shutdown.patch