[S390] irq: fix service signal external interrupt handling

Interrupt sources like pfault, sclp, dasd_diag and virtio all use the
service signal external interrupt subclass mask in control register 0
to enable and disable the corresponding interrupt.
Because no reference counting is implemented each subsystem thinks it
is the only user of subclass and sets and clears the bit like it wants.
This leads to case that unloading the dasd diag module under z/VM
causes both sclp and pfault interrupts to be masked. The result will
be locked up system sooner or later.
Fix this by introducing a new way to set (register) and clear
(unregister) the service signal subclass mask bit in cr0.
Also convert all drivers.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

3 files changed, 6 insertions, 6 deletions

diff --git a/drivers/s390/block/dasd_diag.c b/drivers/s390/block/dasd_diag.c
index 85dddb1..5e8e82d 100644
--- a/drivers/s390/block/dasd_diag.c
+++ b/drivers/s390/block/dasd_diag.c
@@ -642,7 +642,7 @@ dasd_diag_init(void)
 	}
 	ASCEBC(dasd_diag_discipline.ebcname, 4);
 
-	ctl_set_bit(0, 9);
+	service_subclass_irq_register();
 	register_external_interrupt(0x2603, dasd_ext_handler);
 	dasd_diag_discipline_pointer = &dasd_diag_discipline;
 	return 0;
@@ -652,7 +652,7 @@ static void __exit
 dasd_diag_cleanup(void)
 {
 	unregister_external_interrupt(0x2603, dasd_ext_handler);
-	ctl_clear_bit(0, 9);
+	service_subclass_irq_unregister();
 	dasd_diag_discipline_pointer = NULL;
 }
 
diff --git a/drivers/s390/char/sclp.c b/drivers/s390/char/sclp.c
index b76c61f..b37b98c 100644
--- a/drivers/s390/char/sclp.c
+++ b/drivers/s390/char/sclp.c
@@ -885,12 +885,12 @@ sclp_check_interface(void)
 		spin_unlock_irqrestore(&sclp_lock, flags);
 		/* Enable service-signal interruption - needs to happen
 		 * with IRQs enabled. */
-		ctl_set_bit(0, 9);
+		service_subclass_irq_register();
 		/* Wait for signal from interrupt or timeout */
 		sclp_sync_wait();
 		/* Disable service-signal interruption - needs to happen
 		 * with IRQs enabled. */
-		ctl_clear_bit(0,9);
+		service_subclass_irq_unregister();
 		spin_lock_irqsave(&sclp_lock, flags);
 		del_timer(&sclp_request_timer);
 		if (sclp_init_req.status == SCLP_REQ_DONE &&
@@ -1070,7 +1070,7 @@ sclp_init(void)
 	spin_unlock_irqrestore(&sclp_lock, flags);
 	/* Enable service-signal external interruption - needs to happen with
 	 * IRQs enabled. */
-	ctl_set_bit(0, 9);
+	service_subclass_irq_register();
 	sclp_init_mask(1);
 	return 0;
 
diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c
index 607998f..724b592 100644
--- a/drivers/s390/kvm/kvm_virtio.c
+++ b/drivers/s390/kvm/kvm_virtio.c
@@ -441,7 +441,7 @@ static int __init kvm_devices_init(void)
 
 	INIT_WORK(&hotplug_work, hotplug_devices);
 
-	ctl_set_bit(0, 9);
+	service_subclass_irq_register();
 	register_external_interrupt(0x2603, kvm_extint_handler);
 
 	scan_devices();