[PATCH 3.16 350/370] ipv6: addrconf: Avoid addrconf_disable_change() using RCU read-side lock

Ben Hutchings
2017-03-10T12:11:49Z

From: Kefeng Wang <wangkefeng.wang@huawei.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@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/ipv6/addrconf.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -4837,8 +4837,7 @@ 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);
@@ -4847,7 +4846,6 @@ 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)