[PATCH] powerpc/eeh: Fix eeh_dev_check_failure() for PE#0

[Oliver O'Halloran <oohall@gmail.com>]

In commit 269e583357df ("powerpc/eeh: Delete eeh_pe->config_addr") the
following simplification was made:

-       if (!pe->addr && !pe->config_addr) {
+       if (!pe->addr) {
                eeh_stats.no_cfg_addr++;
                return 0;
        }

This introduced a bug which causes EEH checking to be skipped for devices
in PE#0.

Before the change above the check would always pass since atleast one of
the two PE addresses would be non-zero in all circumstances. On PowerNV
pe->config_addr was the be the BDFN of the first device added to the PE.
The zero BDFN is reserved for the PHB's root port, but this is fine since
for obscure platform reasons the root port is never assigned to PE#0.

Similarly, on pseries pe->addr has always been non-zero for the reasons
outlined in commit 42de19d5ef71 ("powerpc/pseries/eeh: Allow zero to be a
valid PE configuration address").

We can fix the problem by deleting the block entirely The original
purpose of this test was to avoid performing EEH checks on devices there
were not on an EEH capable bus. In modern Linux the edev->pe pointer will
be NULL for devices that are not on an EEH capable bus. The code block
immediately above this one already checks for the edev->pe == NULL case
so this test (new and old) is entirely redundant.

Ideally we'd delete eeh_stats.no_cfg_addr too since nothing increments it
any more. Unfortunately, that information is exposed via /proc/powerpc/eeh
which means it's technically ABI. We could make it hard-coded, but that's
a change for another patch.

Fixes: 269e583357df ("powerpc/eeh: Delete eeh_pe->config_addr")
Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
---
 arch/powerpc/kernel/eeh.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c
index 4da880759a8b..7dd03d47693f 100644
--- a/arch/powerpc/kernel/eeh.c
+++ b/arch/powerpc/kernel/eeh.c
@@ -470,11 +470,6 @@ int eeh_dev_check_failure(struct eeh_dev *edev)
 		return 0;
 	}
 
-	if (!pe->addr) {
-		eeh_stats.no_cfg_addr++;
-		return 0;
-	}
-
 	/*
 	 * On PowerNV platform, we might already have fenced PHB
 	 * there and we need take care of that firstly.
-- 
2.26.2