[SRU][Bionic][Patch 1/1] s390/qdio: clear intparm during shutdown

[frank.heimes at canonical.com]

From: Julian Wiedmann <jwi at linux.vnet.ibm.com>

BugLink: https://bugs.launchpad.net/bugs/1828394

During shutdown, qdio returns its ccw device back to control by the
upper-layer driver. But there is a remote chance that by the time where the
IRQ handler gets switched back, the interrupt for the preceding
ccw_device_{clear,halt} hasn't been presented yet.
Upper-layer drivers would then need to handle this IRQ - and since the IO
is issued with an intparm, it could very well be confused with whatever
intparm mechanism the driver uses itself (eg intparm == request address).

So when switching over the IRQ handler, also clear the intparm and have
upper-layer drivers deal with any such delayed interrupt as if it was
unsolicited.

Suggested-by: Sebastian Ott <sebott at linux.vnet.ibm.com>
Signed-off-by: Julian Wiedmann <jwi at linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky at de.ibm.com>
(cherry picked from commit 89286320a236d245834075fa13adb0bdd827ecaa)
Signed-off-by: Frank Heimes <frank.heimes at canonical.com>
---
 drivers/s390/cio/qdio_main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/cio/qdio_main.c b/drivers/s390/cio/qdio_main.c
index d76df58..8842be6 100644
--- a/drivers/s390/cio/qdio_main.c
+++ b/drivers/s390/cio/qdio_main.c
@@ -1218,8 +1218,10 @@ int qdio_shutdown(struct ccw_device *cdev, int how)
 	qdio_shutdown_thinint(irq_ptr);
 
 	/* restore interrupt handler */
-	if ((void *)cdev->handler == (void *)qdio_int_handler)
+	if ((void *)cdev->handler == (void *)qdio_int_handler) {
 		cdev->handler = irq_ptr->orig_handler;
+		cdev->private->intparm = 0;
+	}
 	spin_unlock_irq(get_ccwdev_lock(cdev));
 
 	qdio_set_state(irq_ptr, QDIO_IRQ_STATE_INACTIVE);
-- 
2.7.4