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

Tim Gardner tim.gardner at canonical.com
Tue Jul 5 19:57:44 UTC 2016

From: "Guilherme G. Piccoli" <gpiccoli at 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

Cc: stable at vger.kernel.org # v4.1+
Reviewed-by: Gavin Shan <gwshan at linux.vnet.ibm.com>
Signed-off-by: Guilherme G. Piccoli <gpiccoli at linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
(cherry picked from commit c2078d9ef600bdbe568c89e5ddc2c6f15b7982c8)
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
 arch/powerpc/kernel/eeh.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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)
 	if (!eeh_has_flag(EEH_PROBE_MODE_DEVTREE))

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