[PATCH v07 5/9] numa: Disable/enable arch_update_cpu_topology

[Michael Bringmann <mwb@linux.vnet.ibm.com>]

numa: Provide mechanism to disable/enable operation of
arch_update_cpu_topology/numa_update_cpu_topology.  This is
a simple tool to eliminate some avenues for thread deadlock
observed during system execution.

Signed-off-by: Michael Bringmann <mwb@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/topology.h |   10 ++++++++++
 arch/powerpc/mm/numa.c              |   14 ++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/arch/powerpc/include/asm/topology.h b/arch/powerpc/include/asm/topology.h
index 16b0778..d9ceba6 100644
--- a/arch/powerpc/include/asm/topology.h
+++ b/arch/powerpc/include/asm/topology.h
@@ -43,6 +43,8 @@ static inline int pcibus_to_node(struct pci_bus *bus)
 extern int sysfs_add_device_to_node(struct device *dev, int nid);
 extern void sysfs_remove_device_from_node(struct device *dev, int nid);
 extern int numa_update_cpu_topology(bool cpus_locked);
+extern void arch_update_cpu_topology_suspend(void);
+extern void arch_update_cpu_topology_resume(void);
 
 static inline void update_numa_cpu_lookup_table(unsigned int cpu, int node)
 {
@@ -82,6 +84,14 @@ static inline int numa_update_cpu_topology(bool cpus_locked)
 	return 0;
 }
 
+static inline void arch_update_cpu_topology_suspend(void)
+{
+}
+
+static inline void arch_update_cpu_topology_resume(void)
+{
+}
+
 static inline void update_numa_cpu_lookup_table(unsigned int cpu, int node) {}
 
 #endif /* CONFIG_NUMA */
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index b22e27a..2352489 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -1079,6 +1079,7 @@ struct topology_update_data {
 static int topology_timer_secs = 1;
 static int topology_inited;
 static int topology_update_needed;
+static int topology_update_enabled = 1;
 static struct mutex topology_update_lock;
 
 /*
@@ -1313,6 +1314,9 @@ int numa_update_cpu_topology(bool cpus_locked)
 		return 0;
 	}
 
+	if (!topology_update_enabled)
+		return 0;
+
 	weight = cpumask_weight(&cpu_associativity_changes_mask);
 	if (!weight)
 		return 0;
@@ -1439,6 +1443,16 @@ int arch_update_cpu_topology(void)
 	return numa_update_cpu_topology(true);
 }
 
+void arch_update_cpu_topology_suspend(void)
+{
+	topology_update_enabled = 0;
+}
+
+void arch_update_cpu_topology_resume(void)
+{
+	topology_update_enabled = 1;
+}
+
 static void topology_work_fn(struct work_struct *work)
 {
 	rebuild_sched_domains();