[S390] appldata: prevent cpu hotplug when walking cpu_online_map.

Use get_online_cpus() to prevent cpu hotplug in situations where
for_each_online_cpu() is called.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/arch/s390/appldata/appldata_base.c b/arch/s390/appldata/appldata_base.c
index 655d52543e2d..ad40729bec3d 100644
--- a/arch/s390/appldata/appldata_base.c
+++ b/arch/s390/appldata/appldata_base.c
@@ -130,6 +130,7 @@ static void appldata_work_fn(struct work_struct *work)
 
         P_DEBUG("  -= Work Queue =-\n");
         i = 0;
+        get_online_cpus();
         spin_lock(&appldata_ops_lock);
         list_for_each(lh, &appldata_ops_list) {
                 ops = list_entry(lh, struct appldata_ops, list);
@@ -140,6 +141,7 @@ static void appldata_work_fn(struct work_struct *work)
                 }
         }
         spin_unlock(&appldata_ops_lock);
+        put_online_cpus();
 }
 
 /*
@@ -266,12 +268,14 @@ appldata_timer_handler(ctl_table *ctl, int write, struct file *filp,
         len = *lenp;
         if (copy_from_user(buf, buffer, len > sizeof(buf) ? sizeof(buf) : len))
                 return -EFAULT;
+        get_online_cpus();
         spin_lock(&appldata_timer_lock);
         if (buf[0] == '1')
                 __appldata_vtimer_setup(APPLDATA_ADD_TIMER);
         else if (buf[0] == '0')
                 __appldata_vtimer_setup(APPLDATA_DEL_TIMER);
         spin_unlock(&appldata_timer_lock);
+        put_online_cpus();
 out:
         *lenp = len;
         *ppos += len;
@@ -314,10 +318,12 @@ appldata_interval_handler(ctl_table *ctl, int write, struct file *filp,
                 return -EINVAL;
         }
 
+        get_online_cpus();
         spin_lock(&appldata_timer_lock);
         appldata_interval = interval;
         __appldata_vtimer_setup(APPLDATA_MOD_TIMER);
         spin_unlock(&appldata_timer_lock);
+        put_online_cpus();
 
         P_INFO("Monitoring CPU interval set to %u milliseconds.\n",
                  interval);
@@ -556,8 +562,10 @@ static int __init appldata_init(void)
                 return -ENOMEM;
         }
 
+        get_online_cpus();
         for_each_online_cpu(i)
                 appldata_online_cpu(i);
+        put_online_cpus();
 
         /* Register cpu hotplug notifier */
         register_hotcpu_notifier(&appldata_nb);