s390/cio: use device_lock to synchronize calls to the ccwgroup driver

When calling set_{on,off}line of a ccwgroup device driver we hold
the module reference of the owner. This is pretty useless - we don't
want to prevent module unloading but driver unbinding. Use the
driver core's device_lock instead.

Reviewed-by: Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 6 insertions, 6 deletions

diff --git a/drivers/s390/cio/ccwgroup.c b/drivers/s390/cio/ccwgroup.c
index 959135a01847..fd3367a1dc7a 100644
--- a/drivers/s390/cio/ccwgroup.c
+++ b/drivers/s390/cio/ccwgroup.c
@@ -128,14 +128,14 @@ static ssize_t ccwgroup_online_store(struct device *dev,
                                      const char *buf, size_t count)
 {
         struct ccwgroup_device *gdev = to_ccwgroupdev(dev);
-        struct ccwgroup_driver *gdrv = to_ccwgroupdrv(dev->driver);
         unsigned long value;
         int ret;
 
-        if (!dev->driver)
-                return -EINVAL;
-        if (!try_module_get(gdrv->driver.owner))
-                return -EINVAL;
+        device_lock(dev);
+        if (!dev->driver) {
+                ret = -EINVAL;
+                goto out;
+        }
 
         ret = kstrtoul(buf, 0, &value);
         if (ret)
@@ -148,7 +148,7 @@ static ssize_t ccwgroup_online_store(struct device *dev,
         else
                 ret = -EINVAL;
 out:
-        module_put(gdrv->driver.owner);
+        device_unlock(dev);
         return (ret == 0) ? count : ret;
 }