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>
This commit is contained in:
Martin Kepplinger 2015-03-23 13:59:46 +01:00 committed by Greg Kroah-Hartman
parent ab3ae0096a
commit 03190c67ff

View File

@ -169,7 +169,9 @@ static const struct file_operations misc_fops = {
* 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.