From e6c929d473ea6fa69db37e6df56104ab2d4e4f24 Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Tue, 20 Jan 2009 11:02:28 +0000
Subject: [PATCH] --- yaml --- r: 133881 b: refs/heads/master c:
 38231b7a8d1b74c920822640d1ce8eb8046377fb h: refs/heads/master i:   133879:
 6e7624ac03e1278f96eca30b06807e0ea216722f v: v3

---
 [refs]                  |  2 +-
 trunk/drivers/net/tun.c | 24 +++++++++++++++++-------
 2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/[refs] b/[refs]
index 38a05ecb1c03..6631b68e7369 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 36b50bab53207daf34be63ca62fb8b0b08dc6e6b
+refs/heads/master: 38231b7a8d1b74c920822640d1ce8eb8046377fb
diff --git a/trunk/drivers/net/tun.c b/trunk/drivers/net/tun.c
index dfbf58659771..fa93160bf522 100644
--- a/trunk/drivers/net/tun.c
+++ b/trunk/drivers/net/tun.c
@@ -115,25 +115,33 @@ static int tun_attach(struct tun_struct *tun, struct file *file)
 {
 	struct tun_file *tfile = file->private_data;
 	const struct cred *cred = current_cred();
+	int err;
 
 	ASSERT_RTNL();
 
-	if (tfile->tun)
-		return -EINVAL;
-
-	if (tun->tfile)
-		return -EBUSY;
-
 	/* Check permissions */
 	if (((tun->owner != -1 && cred->euid != tun->owner) ||
 	     (tun->group != -1 && cred->egid != tun->group)) &&
 		!capable(CAP_NET_ADMIN))
 		return -EPERM;
 
+	netif_tx_lock_bh(tun->dev);
+
+	err = -EINVAL;
+	if (tfile->tun)
+		goto out;
+
+	err = -EBUSY;
+	if (tun->tfile)
+		goto out;
+
+	err = 0;
 	tfile->tun = tun;
 	tun->tfile = tfile;
 
-	return 0;
+out:
+	netif_tx_unlock_bh(tun->dev);
+	return err;
 }
 
 static void __tun_detach(struct tun_struct *tun)
@@ -141,8 +149,10 @@ static void __tun_detach(struct tun_struct *tun)
 	struct tun_file *tfile = tun->tfile;
 
 	/* Detach from net device */
+	netif_tx_lock_bh(tun->dev);
 	tfile->tun = NULL;
 	tun->tfile = NULL;
+	netif_tx_unlock_bh(tun->dev);
 
 	/* Drop read queue */
 	skb_queue_purge(&tun->readq);