iucv: prevent cpu hotplug when walking cpu_online_map.

The code used preempt_disable() to prevent cpu hotplug, however that
doesn't protect for cpus being added. So use get_online_cpus() instead.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Ursula Braun <braunu@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 7 insertions, 4 deletions

diff --git a/net/iucv/iucv.c b/net/iucv/iucv.c
index 2d43175b0cdb..531a206ce7a6 100644
--- a/net/iucv/iucv.c
+++ b/net/iucv/iucv.c
@@ -474,14 +474,14 @@ static void iucv_setmask_mp(void)
 {
         int cpu;
 
-        preempt_disable();
+        get_online_cpus();
         for_each_online_cpu(cpu)
                 /* Enable all cpus with a declared buffer. */
                 if (cpu_isset(cpu, iucv_buffer_cpumask) &&
                     !cpu_isset(cpu, iucv_irq_cpumask))
                         smp_call_function_single(cpu, iucv_allow_cpu,
                                                  NULL, 0, 1);
-        preempt_enable();
+        put_online_cpus();
 }
 
 /**
@@ -521,16 +521,17 @@ static int iucv_enable(void)
                 goto out;
         /* Declare per cpu buffers. */
         rc = -EIO;
-        preempt_disable();
+        get_online_cpus();
         for_each_online_cpu(cpu)
                 smp_call_function_single(cpu, iucv_declare_cpu, NULL, 0, 1);
-        preempt_enable();
         if (cpus_empty(iucv_buffer_cpumask))
                 /* No cpu could declare an iucv buffer. */
                 goto out_path;
+        put_online_cpus();
         return 0;
 
 out_path:
+        put_online_cpus();
         kfree(iucv_path_table);
 out:
         return rc;
@@ -545,7 +546,9 @@ out:
  */
 static void iucv_disable(void)
 {
+        get_online_cpus();
         on_each_cpu(iucv_retrieve_cpu, NULL, 0, 1);
+        put_online_cpus();
         kfree(iucv_path_table);
 }