ARM: cpu topology: Add update_cpu_topology function

arch_update_cpu_topology function is called by the scheduler
before building its sched_domain hierarchy. Prepare the update
of the cpu topology masks in this function in addition to set
it in the the store_cpu_topology which is executed only once per cpu.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>

1 files changed, 87 insertions, 21 deletions

diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
index 8200deaa14f..90352cbb6d2 100644
--- a/arch/arm/kernel/topology.c
+++ b/arch/arm/kernel/topology.c
@@ -43,12 +43,76 @@
 
 struct cputopo_arm cpu_topology[NR_CPUS];
 
+/*
+ * cpu topology mask management
+ */
+
+unsigned int advanced_topology = 0;
+
+/*
+ * default topology function
+ */
+
 const struct cpumask *cpu_coregroup_mask(int cpu)
 {
 	return &cpu_topology[cpu].core_sibling;
 }
 
 /*
+ * clear cpu topology masks
+ */
+static void clear_cpu_topology_mask(void)
+{
+	unsigned int cpuid;
+	for_each_possible_cpu(cpuid) {
+		struct cputopo_arm *cpuid_topo = &(cpu_topology[cpuid]);
+		cpumask_clear(&cpuid_topo->core_sibling);
+		cpumask_clear(&cpuid_topo->thread_sibling);
+	}
+	smp_wmb();
+}
+
+/*
+ * default_cpu_topology_mask set the core and thread mask as described in the
+ * ARM ARM
+ */
+static inline void default_cpu_topology_mask(unsigned int cpuid)
+{
+	struct cputopo_arm *cpuid_topo = &cpu_topology[cpuid];
+	unsigned int cpu;
+
+	for_each_possible_cpu(cpu) {
+		struct cputopo_arm *cpu_topo = &cpu_topology[cpu];
+
+		if (cpuid_topo->socket_id == cpu_topo->socket_id) {
+			cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
+			if (cpu != cpuid)
+				cpumask_set_cpu(cpu,
+					&cpuid_topo->core_sibling);
+
+			if (cpuid_topo->core_id == cpu_topo->core_id) {
+				cpumask_set_cpu(cpuid,
+					&cpu_topo->thread_sibling);
+				if (cpu != cpuid)
+					cpumask_set_cpu(cpu,
+						&cpuid_topo->thread_sibling);
+			}
+		}
+	}
+	smp_wmb();
+}
+
+static void normal_cpu_topology_mask(void)
+{
+	unsigned int cpuid;
+
+	for_each_possible_cpu(cpuid) {
+		default_cpu_topology_mask(cpuid);
+	}
+	smp_wmb();
+}
+
+/*
  * store_cpu_topology is called at boot when only one cpu is running
  * and with the mutex cpu_hotplug.lock locked, when several cpus have booted,
  * which prevents simultaneous write access to cpu_topology array
@@ -57,7 +121,6 @@ void store_cpu_topology(unsigned int cpuid)
 {
 	struct cputopo_arm *cpuid_topo = &cpu_topology[cpuid];
 	unsigned int mpidr;
-	unsigned int cpu;
 
 	/* If the cpu topology has been already set, just return */
 	if (cpuid_topo->core_id != -1)
@@ -99,26 +162,11 @@ void store_cpu_topology(unsigned int cpuid)
 		cpuid_topo->socket_id = -1;
 	}
 
-	/* update core and thread sibling masks */
-	for_each_possible_cpu(cpu) {
-		struct cputopo_arm *cpu_topo = &cpu_topology[cpu];
-
-		if (cpuid_topo->socket_id == cpu_topo->socket_id) {
-			cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
-			if (cpu != cpuid)
-				cpumask_set_cpu(cpu,
-					&cpuid_topo->core_sibling);
-
-			if (cpuid_topo->core_id == cpu_topo->core_id) {
-				cpumask_set_cpu(cpuid,
-					&cpu_topo->thread_sibling);
-				if (cpu != cpuid)
-					cpumask_set_cpu(cpu,
-						&cpuid_topo->thread_sibling);
-			}
-		}
-	}
-	smp_wmb();
+	/*
+	 * The core and thread sibling masks can also be updated during the
+	 * call of arch_update_cpu_topology
+	 */
+	default_cpu_topology_mask(cpuid);
 
 	printk(KERN_INFO "CPU%u: thread %d, cpu %d, socket %d, mpidr %x\n",
 		cpuid, cpu_topology[cpuid].thread_id,
@@ -127,6 +175,24 @@ void store_cpu_topology(unsigned int cpuid)
 }
 
 /*
+ * arch_update_cpu_topology is called by the scheduler before building
+ * a new sched_domain hierarchy.
+ */
+int arch_update_cpu_topology(void)
+{
+	if (!advanced_topology)
+		return 0;
+
+	/* clear core mask */
+	clear_cpu_topology_mask();
+
+	/* update core and thread sibling masks */
+	normal_cpu_topology_mask();
+
+	return 1;
+}
+
+/*
  * init_cpu_topology is called at boot when only one cpu is running
  * which prevent simultaneous write access to cpu_topology array
  */