RDMA: Check for NULL mode in .devnode methods

Commits 71c29bd5c235 ("IB/uverbs: Add devnode method to set path/mode")
and c3af0980ce01 ("IB: Add devnode methods to cm_class and umad_class")
added devnode methods that set the mode.

However, these methods don't check for a NULL mode, and so we get a
crash when unloading modules because devtmpfs_delete_node() calls
device_get_devnode() with mode == NULL.

Add the missing checks.

Signed-off-by: Goldwyn Rodrigues <[e-mail]>
[ Also fix cm.c. - Roland ]
Signed-off-by: Roland Dreier <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/infiniband/core/cm.c

···
 
 static char *cm_devnode(struct device *dev, mode_t *mode)
 {
-	*mode = 0666;
+	if (mode)
+		*mode = 0666;
 	return kasprintf(GFP_KERNEL, "infiniband/%s", dev_name(dev));
 }
 

drivers/infiniband/core/uverbs_main.c

···
 
 static char *uverbs_devnode(struct device *dev, mode_t *mode)
 {
-	*mode = 0666;
+	if (mode)
+		*mode = 0666;
 	return kasprintf(GFP_KERNEL, "infiniband/%s", dev_name(dev));
 }