[PATCH 4/4] lguest: explicitly set miscdevice's private_data NULL

From: Martin Kepplinger
Date: Mon Mar 23 2015 - 09:01:58 EST


There is a proposed change to the miscdevice's behaviour on open(). Currently
file->private_data stays NULL, but only because we don't have an open-entry in
struct file_operations.

This may change so that private_data, more consistently, is always set to
struct miscdevice, not only *if* the driver has it's own open() routine and
fops-entry, see https://lkml.org/lkml/2014/12/4/939

In short: If we rely on file->private_data being NULL, we should ensure
it is NULL ourselves.

Signed-off-by: Martin Kepplinger <martink@xxxxxxxxx>
---
drivers/lguest/lguest_user.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index c4c6113..30c6068 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -339,6 +339,13 @@ static ssize_t write(struct file *file, const char __user *in,
}
}

+static int open(struct inode *inode, struct file *file)
+{
+ file->private_data = NULL;
+
+ return 0;
+}
+
/*L:060
* The final piece of interface code is the close() routine. It reverses
* everything done in initialize(). This is usually called because the
@@ -409,6 +416,7 @@ static int close(struct inode *inode, struct file *file)
*/
static const struct file_operations lguest_fops = {
.owner = THIS_MODULE,
+ .open = open,
.release = close,
.write = write,
.read = read,
--
2.1.4

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