[PATCH 4.6 079/121] Revert "powerpc/eeh: Fix crash in eeh_add_device_early() on Cell"

From: Greg Kroah-Hartman
Date: Sun Jun 05 2016 - 17:56:06 EST

4.6-stable review patch. If anyone has any objections, please let me know.


From: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxxxxxxxxxx>

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

Reviewed-by: Gavin Shan <gwshan@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

arch/powerpc/kernel/eeh.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/powerpc/kernel/eeh.c
+++ b/arch/powerpc/kernel/eeh.c
@@ -1068,7 +1068,7 @@ void eeh_add_device_early(struct pci_dn
struct pci_controller *phb;
struct eeh_dev *edev = pdn_to_eeh_dev(pdn);

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

if (!eeh_has_flag(EEH_PROBE_MODE_DEVTREE))