linux-kernel - [PATCH 4.4 14/20] ipv6: addrconf: Avoid addrconf_disable

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Date:   Thu,  2 Feb 2017 19:33:47 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Kefeng Wang <wangkefeng.wang@...wei.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.4 14/20] ipv6: addrconf: Avoid addrconf_disable_change() using RCU read-side lock

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Kefeng Wang <wangkefeng.wang@...wei.com>


[ Upstream commit 03e4deff4987f79c34112c5ba4eb195d4f9382b0 ]

Just like commit 4acd4945cd1e ("ipv6: addrconf: Avoid calling
netdevice notifiers with RCU read-side lock"), it is unnecessary
to make addrconf_disable_change() use RCU iteration over the
netdev list, since it already holds the RTNL lock, or we may meet
Illegal context switch in RCU read-side critical section.

Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/ipv6/addrconf.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -5244,8 +5244,7 @@ static void addrconf_disable_change(stru
 	struct net_device *dev;
 	struct inet6_dev *idev;
 
-	rcu_read_lock();
-	for_each_netdev_rcu(net, dev) {
+	for_each_netdev(net, dev) {
 		idev = __in6_dev_get(dev);
 		if (idev) {
 			int changed = (!idev->cnf.disable_ipv6) ^ (!newf);
@@ -5254,7 +5253,6 @@ static void addrconf_disable_change(stru
 				dev_disable_change(idev);
 		}
 	}
-	rcu_read_unlock();
 }
 
 static int addrconf_disable_ipv6(struct ctl_table *table, int *p, int newf)