[3.5.y.z extended stable] Patch "PCI: Enable INTx in pci_reenable_device() only when MSI/MSI-X not" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    PCI: Enable INTx in pci_reenable_device() only when MSI/MSI-X not

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 085166d86fac2cd485800ced532774accca1bc97 Mon Sep 17 00:00:00 2001
From: Bjorn Helgaas <bhelgaas at google.com>
Date: Tue, 11 Mar 2014 14:22:19 -0600
Subject: PCI: Enable INTx in pci_reenable_device() only when MSI/MSI-X not
 enabled

commit 3cdeb713dc66057b50682048c151eae07b186c42 upstream.

Andreas reported that after 1f42db786b14 ("PCI: Enable INTx if BIOS left
them disabled"), pciehp surprise removal stopped working.

This happens because pci_reenable_device() on the hotplug bridge (used in
the pciehp_configure_device() path) clears the Interrupt Disable bit, which
apparently breaks the bridge's MSI hotplug event reporting.

Previously we cleared the Interrupt Disable bit in do_pci_enable_device(),
which is used by both pci_enable_device() and pci_reenable_device().  But
we use pci_reenable_device() after the driver may have enabled MSI or
MSI-X, and we *set* Interrupt Disable as part of enabling MSI/MSI-X.

This patch clears Interrupt Disable only when MSI/MSI-X has not been
enabled.

Fixes: 1f42db786b14 PCI: Enable INTx if BIOS left them disabled
Link: https://bugzilla.kernel.org/show_bug.cgi?id=71691
Reported-and-tested-by: Andreas Noever <andreas.noever at gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
CC: Sarah Sharp <sarah.a.sharp at linux.intel.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/pci/pci.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 42b9983..bf0df20 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -1145,6 +1145,9 @@ static int do_pci_enable_device(struct pci_dev *dev, int bars)
 		return err;
 	pci_fixup_device(pci_fixup_enable, dev);

+	if (dev->msi_enabled || dev->msix_enabled)
+		return 0;
+
 	pci_read_config_byte(dev, PCI_INTERRUPT_PIN, &pin);
 	if (pin) {
 		pci_read_config_word(dev, PCI_COMMAND, &cmd);
--
1.9.1