linux-kernel - [PATCH 3/3] lguest: force file->private

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Message-Id: <1413678660-29669-3-git-send-email-martink@posteo.de>
Date:	Sun, 19 Oct 2014 02:31:00 +0200
From:	Martin Kepplinger <martink@...teo.de>
To:	gregkh@...uxfoundation.org
Cc:	arnd@...db.de, akpm@...ux-foundation.org,
	linux-kernel@...r.kernel.org, Martin Kepplinger <martink@...teo.de>
Subject: [PATCH 3/3] lguest: force file->private_data to be NULL on open()

if we depend on private_data being NULL in write() before initialize()
make sure it is NULL after open().

Signed-off-by: Martin Kepplinger <martink@...teo.de>
---

I'm not completely sure if this patch is needed and am still investigating.
What do you think? open() could be called by the user I guess. Does
lguest_user.c depend on private_data being NULL on a first write()?


 drivers/lguest/lguest_user.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index 4263f4c..30251b7 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -497,6 +497,12 @@ static int close(struct inode *inode, struct file *file)
 	return 0;
 }
 
+static int open(struct inode *inode, struct file *file)
+{
+	/* the miscdevice core sets private_data on open() */
+	file->private_data = NULL;
+}
+
 /*L:000
  * Welcome to our journey through the Launcher!
  *
@@ -514,6 +520,7 @@ 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,
-- 
1.7.10.4

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