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[4.2.y-ckt,stable] Patch "Revert "powerpc/eeh: Fix crash in eeh_add_device_early() on Cell"" has been added to the 4.2.y-ckt tree

Message ID 1465482902-23061-1-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa June 9, 2016, 2:35 p.m. UTC
This is a note to let you know that I have just added a patch titled

    Revert "powerpc/eeh: Fix crash in eeh_add_device_early() on Cell"

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    https://git.launchpad.net/~canonical-kernel/linux/+git/linux-stable-ckt/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt12.

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

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

---8<------------------------------------------------------------

From f23586fe363212456dab1ed1ca4f032c2d28a1a5 Mon Sep 17 00:00:00 2001
From: "Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com>
Date: Mon, 11 Apr 2016 16:17:22 -0300
Subject: Revert "powerpc/eeh: Fix crash in eeh_add_device_early() on Cell"

commit c2078d9ef600bdbe568c89e5ddc2c6f15b7982c8 upstream.

This reverts commit 89a51df5ab1d38b257300b8ac940bbac3bb0eb9b.

The function eeh_add_device_early() is used to perform EEH
initialization in devices added later on the system, like in
hotplug/DLPAR scenarios. Since the commit 89a51df5ab1d ("powerpc/eeh:
Fix crash in eeh_add_device_early() on Cell") a new check was introduced
in this function - Cell has no EEH capabilities which led to kernel oops
if hotplug was performed, so checking for eeh_enabled() was introduced
to avoid the issue.

However, in architectures that EEH is present like pSeries or PowerNV,
we might reach a case in which no PCI devices are present on boot time
and so EEH is not initialized. Then, if a device is added via DLPAR for
example, eeh_add_device_early() fails because eeh_enabled() is false,
and EEH end up not being enabled at all.

This reverts the aforementioned patch since a new verification was
introduced by the commit d91dafc02f42 ("powerpc/eeh: Delay probing EEH
device during hotplug") and so the original Cell issue does not happen
anymore.

Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 arch/powerpc/kernel/eeh.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--
2.7.4
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Patch

diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c
index 01c961d..1109964 100644
--- a/arch/powerpc/kernel/eeh.c
+++ b/arch/powerpc/kernel/eeh.c
@@ -1071,7 +1071,7 @@  void eeh_add_device_early(struct pci_dn *pdn)
 	struct pci_controller *phb;
 	struct eeh_dev *edev = pdn_to_eeh_dev(pdn);

-	if (!edev || !eeh_enabled())
+	if (!edev)
 		return;

 	if (!eeh_has_flag(EEH_PROBE_MODE_DEVTREE))