[PATCH v2 5/9] s390: numa: check the node id consistently for s390

According to Section 6.2.14 from ACPI spec 6.3 [1], the setting
of proximity domain is optional, as below:

This optional object is used to describe proximity domain
associations within a machine. _PXM evaluates to an integer
that identifies a device as belonging to a Proximity Domain
defined in the System Resource Affinity Table (SRAT).

This patch checks node id with the below case before returning
node_to_cpumask_map[node]:
1. if node_id >= nr_node_ids, return cpu_none_mask
2. if node_id < 0, return cpu_online_mask
3. if node_to_cpumask_map[node_id] is NULL, return cpu_online_mask

[1] https://uefi.org/sites/default/files/resources/ACPI_6_3_final_Jan30.pdf

Signed-off-by: Yunsheng Lin <redacted>
---
Note node_to_cpumask_map[node] is already a pointer, so
returning &node_to_cpumask_map[node] does not seem to
be correct, if this is problem, maybe clean it up in another
patch.
---
 arch/s390/include/asm/topology.h | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/s390/include/asm/topology.h b/arch/s390/include/asm/topology.h
index cca406f..75340ca 100644
--- a/arch/s390/include/asm/topology.h
+++ b/arch/s390/include/asm/topology.h

@@ -78,6 +78,12 @@ static inline int cpu_to_node(int cpu)
 #define cpumask_of_node cpumask_of_node
 static inline const struct cpumask *cpumask_of_node(int node)
 {
+	if (node >= nr_node_ids)
+		return cpu_none_mask;
+
+	if (node < 0 || !node_to_cpumask_map[node])
+		return cpu_online_mask;
+
 	return &node_to_cpumask_map[node];
 }
 

-- 
2.8.1