3 files changed, 26 insertions, 1 deletions

diff --git a/arch/s390/include/asm/s390_ext.h b/arch/s390/include/asm/s390_ext.h
index 080876d5f196..85b2154b899f 100644
--- a/arch/s390/include/asm/s390_ext.h
+++ b/arch/s390/include/asm/s390_ext.h
@@ -13,5 +13,7 @@ typedef void (*ext_int_handler_t)(unsigned int, unsigned int, unsigned long);
 
 int register_external_interrupt(__u16 code, ext_int_handler_t handler);
 int unregister_external_interrupt(__u16 code, ext_int_handler_t handler);
+void service_subclass_irq_register(void);
+void service_subclass_irq_unregister(void);
 
 #endif /* _S390_EXTINT_H */
diff --git a/arch/s390/kernel/s390_ext.c b/arch/s390/kernel/s390_ext.c
index 185029919c4d..87b5c532abf1 100644
--- a/arch/s390/kernel/s390_ext.c
+++ b/arch/s390/kernel/s390_ext.c
@@ -106,3 +106,26 @@ void __irq_entry do_extint(struct pt_regs *regs, unsigned int ext_int_code,
         irq_exit();
         set_irq_regs(old_regs);
 }
+
+static DEFINE_SPINLOCK(sc_irq_lock);
+static int sc_irq_refcount;
+
+void service_subclass_irq_register(void)
+{
+        spin_lock(&sc_irq_lock);
+        if (!sc_irq_refcount)
+                ctl_set_bit(0, 9);
+        sc_irq_refcount++;
+        spin_unlock(&sc_irq_lock);
+}
+EXPORT_SYMBOL(service_subclass_irq_register);
+
+void service_subclass_irq_unregister(void)
+{
+        spin_lock(&sc_irq_lock);
+        sc_irq_refcount--;
+        if (!sc_irq_refcount)
+                ctl_clear_bit(0, 9);
+        spin_unlock(&sc_irq_lock);
+}
+EXPORT_SYMBOL(service_subclass_irq_unregister);
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index e46ba2927424..6e922b50efa4 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -613,7 +613,7 @@ static int __init pfault_irq_init(void)
         rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
         if (rc)
                 goto out_pfault;
-        ctl_set_bit(0, 9);
+        service_subclass_irq_register();
         hotcpu_notifier(pfault_cpu_notify, 0);
         return 0;