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[2/4,Xenial,SRU] Revert "powerpc/eeh: Fix crash in eeh_add_device_early() on Cell"

Message ID 1467748666-7986-3-git-send-email-tim.gardner@canonical.com
State New
Headers show

Commit Message

Tim Gardner July 5, 2016, 7:57 p.m. UTC 
From: "Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com>

BugLink: http://bugs.launchpad.net/bugs/1599250

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.

Cc: stable@vger.kernel.org # v4.1+
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>
(cherry picked from commit c2078d9ef600bdbe568c89e5ddc2c6f15b7982c8)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
---
 arch/powerpc/kernel/eeh.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c
index 40e4d4a..b34e8a5 100644
--- a/arch/powerpc/kernel/eeh.c
+++ b/arch/powerpc/kernel/eeh.c
@@ -1072,7 +1072,7 @@  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))