3 files changed, 50 insertions, 10 deletions

diff --git a/arch/powerpc/platforms/pseries/dlpar.c b/arch/powerpc/platforms/pseries/dlpar.c
index 642e1b2e5c42..fd2f0afeb4de 100644
--- a/arch/powerpc/platforms/pseries/dlpar.c
+++ b/arch/powerpc/platforms/pseries/dlpar.c
@@ -436,6 +436,18 @@ int dlpar_release_drc(u32 drc_index)
 
 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
 
+static DEFINE_MUTEX(pseries_cpu_hotplug_mutex);
+
+void cpu_hotplug_driver_lock()
+{
+        mutex_lock(&pseries_cpu_hotplug_mutex);
+}
+
+void cpu_hotplug_driver_unlock()
+{
+        mutex_unlock(&pseries_cpu_hotplug_mutex);
+}
+
 static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
 {
         struct device_node *dn;
@@ -443,13 +455,18 @@ static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
         char *cpu_name;
         int rc;
 
+        cpu_hotplug_driver_lock();
         rc = strict_strtoul(buf, 0, &drc_index);
-        if (rc)
-                return -EINVAL;
+        if (rc) {
+                rc = -EINVAL;
+                goto out;
+        }
 
         dn = dlpar_configure_connector(drc_index);
-        if (!dn)
-                return -EINVAL;
+        if (!dn) {
+                rc = -EINVAL;
+                goto out;
+        }
 
         /* configure-connector reports cpus as living in the base
          * directory of the device tree.  CPUs actually live in the
@@ -459,7 +476,8 @@ static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
                            GFP_KERNEL);
         if (!cpu_name) {
                 dlpar_free_cc_nodes(dn);
-                return -ENOMEM;
+                rc = -ENOMEM;
+                goto out;
         }
 
         sprintf(cpu_name, "/cpus%s", dn->full_name);
@@ -469,7 +487,8 @@ static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
         rc = dlpar_acquire_drc(drc_index);
         if (rc) {
                 dlpar_free_cc_nodes(dn);
-                return -EINVAL;
+                rc = -EINVAL;
+                goto out;
         }
 
         rc = dlpar_attach_node(dn);
@@ -479,6 +498,8 @@ static ssize_t dlpar_cpu_probe(const char *buf, size_t count)
         }
 
         rc = online_node_cpus(dn);
+out:
+        cpu_hotplug_driver_unlock();
 
         return rc ? rc : count;
 }
@@ -499,26 +520,30 @@ static ssize_t dlpar_cpu_release(const char *buf, size_t count)
                 return -EINVAL;
         }
 
+        cpu_hotplug_driver_lock();
         rc = offline_node_cpus(dn);
         if (rc) {
                 of_node_put(dn);
-                return -EINVAL;
+                rc = -EINVAL;
+                goto out;
         }
 
         rc = dlpar_release_drc(*drc_index);
         if (rc) {
                 of_node_put(dn);
-                return -EINVAL;
+                goto out;
         }
 
         rc = dlpar_detach_node(dn);
         if (rc) {
                 dlpar_acquire_drc(*drc_index);
-                return rc;
+                goto out;
         }
 
         of_node_put(dn);
-        return count;
+out:
+        cpu_hotplug_driver_unlock();
+        return rc ? rc : count;
 }
 
 static int __init pseries_dlpar_init(void)
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 7c03af7b84a9..27fd775375b0 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -35,6 +35,7 @@ static ssize_t __ref store_online(struct sys_device *dev, struct sysdev_attribut
         struct cpu *cpu = container_of(dev, struct cpu, sysdev);
         ssize_t ret;
 
+        cpu_hotplug_driver_lock();
         switch (buf[0]) {
         case '0':
                 ret = cpu_down(cpu->sysdev.id);
@@ -49,6 +50,7 @@ static ssize_t __ref store_online(struct sys_device *dev, struct sysdev_attribut
         default:
                 ret = -EINVAL;
         }
+        cpu_hotplug_driver_unlock();
 
         if (ret >= 0)
                 ret = count;
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index c972f7ccb7d3..e287863ac053 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -117,6 +117,19 @@ extern void put_online_cpus(void);
 #define unregister_hotcpu_notifier(nb)  unregister_cpu_notifier(nb)
 int cpu_down(unsigned int cpu);
 
+#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
+extern void cpu_hotplug_driver_lock(void);
+extern void cpu_hotplug_driver_unlock(void);
+#else
+static inline void cpu_hotplug_driver_lock(void)
+{
+}
+
+static inline void cpu_hotplug_driver_unlock(void)
+{
+}
+#endif
+
 #else           /* CONFIG_HOTPLUG_CPU */
 
 #define get_online_cpus()       do { } while (0)