From: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Date: Wed, 21 Mar 2018 17:17:14 +0100
Subject: s390/qdio: lock device while installing IRQ handler
Git-commit: 7eee12b44eb4c0c30b0eac5946fb59f1460572f6
Patch-mainline: v4.17-rc1
References: git-fixes

During setup, qdio takes control of the presented ccw device and replaces
the device's IRQ handler with its own. To avoid any interference with
conccurent activity on the device, this should be done while holding the
device's lock.

Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Reviewed-by: Benjamin Block <bblock@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/s390/cio/qdio_setup.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/s390/cio/qdio_setup.c
+++ b/drivers/s390/cio/qdio_setup.c
@@ -507,8 +507,10 @@ int qdio_setup_irq(struct qdio_initializ
 	irq_ptr->aqueue = *ciw;
 
 	/* set new interrupt handler */
+	spin_lock_irq(get_ccwdev_lock(irq_ptr->cdev));
 	irq_ptr->orig_handler = init_data->cdev->handler;
 	init_data->cdev->handler = qdio_int_handler;
+	spin_unlock_irq(get_ccwdev_lock(irq_ptr->cdev));
 	return 0;
 out_err:
 	qdio_release_memory(irq_ptr);