iucv: fix kernel panic at reboot

The iucv base layer is initialized during the registration of the
first iucv handler.  If no handler is registered and the
iucv_reboot_event() notifier is called, a missing check can cause
a kernel panic in iucv_block_cpu().  To solve this issue, check the
IRQ masks invoke iucv_block_cpu() for enabled CPUs only.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/net/iucv/iucv.c b/net/iucv/iucv.c
index df082508362d..4fe76ff214c2 100644
--- a/net/iucv/iucv.c
+++ b/net/iucv/iucv.c
@@ -831,8 +831,11 @@ static int iucv_reboot_event(struct notifier_block *this,
 {
         int i;
 
+        if (cpumask_empty(&iucv_irq_cpumask))
+                return NOTIFY_DONE;
+
         get_online_cpus();
-        on_each_cpu(iucv_block_cpu, NULL, 1);
+        on_each_cpu_mask(&iucv_irq_cpumask, iucv_block_cpu, NULL, 1);
         preempt_disable();
         for (i = 0; i < iucv_max_pathid; i++) {
                 if (iucv_path_table[i])