[S390] cio: call ccw driver notify function with lock held

Calling a ccw driver's notify function without the ccw device lock
held opens up a race window between discovery and handling of a change
in the device operational state. As a result, the device driver may
encounter unexpected device malfunction, leading to out-of-retry
situations or similar.

Remove race by extending the ccw device lock from state change
discovery to the calling of the notify function.

Signed-off-by: Peter Oberparleiter <peter.oberparleiter@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 1 insertions, 4 deletions

diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index 1b6c52ef7339..acb78017e7d0 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -2333,13 +2333,11 @@ int dasd_generic_notify(struct ccw_device *cdev, int event)
 {
         struct dasd_device *device;
         struct dasd_ccw_req *cqr;
-        unsigned long flags;
         int ret;
 
-        device = dasd_device_from_cdev(cdev);
+        device = dasd_device_from_cdev_locked(cdev);
         if (IS_ERR(device))
                 return 0;
-        spin_lock_irqsave(get_ccwdev_lock(cdev), flags);
         ret = 0;
         switch (event) {
         case CIO_GONE:
@@ -2369,7 +2367,6 @@ int dasd_generic_notify(struct ccw_device *cdev, int event)
                 ret = 1;
                 break;
         }
-        spin_unlock_irqrestore(get_ccwdev_lock(cdev), flags);
         dasd_put_device(device);
         return ret;
 }