Subject: [PATCH] topology/sysfs: Fix allnoconfig build breakage.

From: "Luck, Tony" <[email-masked]>
Date: Thu, 21 Apr 2022 08:45:34 -0700

drivers/base/topology.c: In function 'topology_is_visible':
drivers/base/topology.c:158:24: warning: unused variable 'dev' [-Wunused-variable]
  158 |         struct device *dev = kobj_to_dev(kobj);

This is because the topology_ppin(dev->id) macro expands to:

	(cpu_data(dev->id).ppin)

and with CONFIG_SMP=n the cpu_data() macro expands to boot_cpu_data
(ignoring its argument) with the end result:

	boot_cpu_data.ppin

My CPP-fu wasn't up to a modification to topology_ppin(), so I added a
(probably redundant) check for "dev" being a NULL pointer.

Fixes: c3702a746ff5 ("topology/sysfs: Hide PPIN on systems that do not support it.")
Reported-by: Stephen Rothwell <[email-masked]>
Signed-off-by: Tony Luck <[email-masked]>

---
Better fixes with clever CPP macro tricks gratefully welcomed
---
 drivers/base/topology.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/base/topology.c b/drivers/base/topology.c
index 706dbf8bf249..31fae51fd340 100644
--- a/drivers/base/topology.c
+++ b/drivers/base/topology.c
@@ -157,7 +157,7 @@ static umode_t topology_is_visible(struct kobject *kobj,
 {
 	struct device *dev = kobj_to_dev(kobj);
 
-	if (attr == &dev_attr_ppin.attr && !topology_ppin(dev->id))
+	if (!dev || (attr == &dev_attr_ppin.attr && !topology_ppin(dev->id)))
 		return 0;
 
 	return attr->mode;
-- 
2.35.1