[S390] zcrypt: fix possible race when unloading zcrypt driver modules

Move try_module_get() call into spin protected block to prevent zcrypt
driver module unload while submitting a request to driver.
Signed-off-by: Ralph Wuerthner <rwuerthn@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/crypto/zcrypt_api.c

@@ -298,14 +298,14 @@ static long zcrypt_rsa_modexpo(struct ica_rsa_modexpo *mex)
 		get_device(&zdev->ap_dev->device);
 		zdev->request_count++;
 		__zcrypt_decrease_preference(zdev);
-		spin_unlock_bh(&zcrypt_device_lock);
 		if (try_module_get(zdev->ap_dev->drv->driver.owner)) {
+			spin_unlock_bh(&zcrypt_device_lock);
 			rc = zdev->ops->rsa_modexpo(zdev, mex);
+			spin_lock_bh(&zcrypt_device_lock);
 			module_put(zdev->ap_dev->drv->driver.owner);
 		}
 		else
 			rc = -EAGAIN;
-		spin_lock_bh(&zcrypt_device_lock);
 		zdev->request_count--;
 		__zcrypt_increase_preference(zdev);
 		put_device(&zdev->ap_dev->device);
@@ -373,14 +373,14 @@ static long zcrypt_rsa_crt(struct ica_rsa_modexpo_crt *crt)
 		get_device(&zdev->ap_dev->device);
 		zdev->request_count++;
 		__zcrypt_decrease_preference(zdev);
-		spin_unlock_bh(&zcrypt_device_lock);
 		if (try_module_get(zdev->ap_dev->drv->driver.owner)) {
+			spin_unlock_bh(&zcrypt_device_lock);
 			rc = zdev->ops->rsa_modexpo_crt(zdev, crt);
+			spin_lock_bh(&zcrypt_device_lock);
 			module_put(zdev->ap_dev->drv->driver.owner);
 		}
 		else
 			rc = -EAGAIN;
-		spin_lock_bh(&zcrypt_device_lock);
 		zdev->request_count--;
 		__zcrypt_increase_preference(zdev);
 		put_device(&zdev->ap_dev->device);
@@ -408,14 +408,14 @@ static long zcrypt_send_cprb(struct ica_xcRB *xcRB)
 		get_device(&zdev->ap_dev->device);
 		zdev->request_count++;
 		__zcrypt_decrease_preference(zdev);
-		spin_unlock_bh(&zcrypt_device_lock);
 		if (try_module_get(zdev->ap_dev->drv->driver.owner)) {
+			spin_unlock_bh(&zcrypt_device_lock);
 			rc = zdev->ops->send_cprb(zdev, xcRB);
+			spin_lock_bh(&zcrypt_device_lock);
 			module_put(zdev->ap_dev->drv->driver.owner);
 		}
 		else
 			rc = -EAGAIN;
-		spin_lock_bh(&zcrypt_device_lock);
 		zdev->request_count--;
 		__zcrypt_increase_preference(zdev);
 		put_device(&zdev->ap_dev->device);