[PATCHv2 2/3] powerpc/cpu: dynmamically to create/destroy the file physical_id during hotplug

[Pingfan Liu <kernelfans@gmail.com>]

In order to cope with the incoming patch [3/3], which causes the dir
/sys/../cpuX is created/destroyed during hotplug, we also need to create
the file cpuX/physical_id dynamically.

Signed-off-by: Pingfan Liu <kernelfans@gmail.com>
Reported-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
Reviewed-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
---
 arch/powerpc/kernel/sysfs.c | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
index 04d0bbd..a05ab5e 100644
--- a/arch/powerpc/kernel/sysfs.c
+++ b/arch/powerpc/kernel/sysfs.c
@@ -716,6 +716,16 @@ static struct device_attribute pa6t_attrs[] = {
 #endif /* HAS_PPC_PMC_PA6T */
 #endif /* HAS_PPC_PMC_CLASSIC */
 
+/* Only valid if CPU is present. */
+static ssize_t show_physical_id(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct cpu *cpu = container_of(dev, struct cpu, dev);
+
+	return sprintf(buf, "%d\n", get_hard_smp_processor_id(cpu->dev.id));
+}
+static DEVICE_ATTR(physical_id, 0444, show_physical_id, NULL);
+
 static int register_cpu_online(unsigned int cpu)
 {
 	struct cpu *c = &per_cpu(cpu_devices, cpu);
@@ -723,6 +733,8 @@ static int register_cpu_online(unsigned int cpu)
 	struct device_attribute *attrs, *pmc_attrs;
 	int i, nattrs;
 
+	device_create_file(&c->dev, &dev_attr_physical_id);
+
 	/* For cpus present at boot a reference was already grabbed in register_cpu() */
 	if (!s->of_node)
 		s->of_node = of_get_cpu_node(cpu, NULL);
@@ -816,6 +828,7 @@ static int unregister_cpu_online(unsigned int cpu)
 
 	BUG_ON(!c->hotpluggable);
 
+	device_remove_file(s, &dev_attr_physical_id);
 #ifdef CONFIG_PPC64
 	if (cpu_has_feature(CPU_FTR_SMT))
 		device_remove_file(s, &dev_attr_smt_snooze_delay);
@@ -1017,16 +1030,6 @@ static void register_nodes(void)
 
 #endif
 
-/* Only valid if CPU is present. */
-static ssize_t show_physical_id(struct device *dev,
-				struct device_attribute *attr, char *buf)
-{
-	struct cpu *cpu = container_of(dev, struct cpu, dev);
-
-	return sprintf(buf, "%d\n", get_hard_smp_processor_id(cpu->dev.id));
-}
-static DEVICE_ATTR(physical_id, 0444, show_physical_id, NULL);
-
 static int __init topology_init(void)
 {
 	int cpu, r;
@@ -1049,7 +1052,6 @@ static int __init topology_init(void)
 		if (cpu_online(cpu) || c->hotpluggable) {
 			register_cpu(c, cpu);
 
-			device_create_file(&c->dev, &dev_attr_physical_id);
 		}
 	}
 	r = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "powerpc/topology:online",
-- 
2.7.4