char: misc: document behaviour of open()
an open syscall now assignes file->private_data to a pointer to the
miscdevice structure. This reminds people not to duplicate code if
they want this and not to depend on it being NULL.
Signed-off-by: Martin Kepplinger <martink@posteo.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/char/misc.c b/drivers/char/misc.c
index ffa97d2..c892c29 100644
--- a/drivers/char/misc.c
+++ b/drivers/char/misc.c
@@ -169,7 +169,9 @@
* the minor number requested is used.
*
* The structure passed is linked into the kernel and may not be
- * destroyed until it has been unregistered.
+ * destroyed until it has been unregistered. By default, an open()
+ * syscall to the device sets file->private_data to point to the
+ * structure. Drivers don't need open in fops for this.
*
* A zero is returned on success and a negative errno code for
* failure.
