ipv6: addrconf: Avoid addrconf_disable_change() using RCU read-side lock

Kefeng Wang · davem330 · commit 03e4deff4987 · 2017-01-19T11:08:53.000-05:00
Just like commit 4acd494 ("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>
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
@@ -5540,8 +5540,7 @@ static void addrconf_disable_change(struct net *net, __s32 newf)
 	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);
@@ -5550,7 +5549,6 @@ static void addrconf_disable_change(struct net *net, __s32 newf)
 				dev_disable_change(idev);
 		}
 	}
-	rcu_read_unlock();
 }
 
 static int addrconf_disable_ipv6(struct ctl_table *table, int *p, int newf)

Original file line number	Diff line number	Diff line change
`@@ -5540,8 +5540,7 @@ static void addrconf_disable_change(struct net *net, __s32 newf)`
`5540`	`5540`	`struct net_device *dev;`
`5541`	`5541`	`struct inet6_dev *idev;`
`5542`	`5542`
`5543`		`- rcu_read_lock();`
`5544`		`- for_each_netdev_rcu(net, dev) {`
	`5543`	`+ for_each_netdev(net, dev) {`
`5545`	`5544`	`idev = __in6_dev_get(dev);`
`5546`	`5545`	`if (idev) {`
`5547`	`5546`	`int changed = (!idev->cnf.disable_ipv6) ^ (!newf);`
`@@ -5550,7 +5549,6 @@ static void addrconf_disable_change(struct net *net, __s32 newf)`
`5550`	`5549`	`dev_disable_change(idev);`
`5551`	`5550`	`}`
`5552`	`5551`	`}`
`5553`		`- rcu_read_unlock();`
`5554`	`5552`	`}`
`5555`	`5553`
`5556`	`5554`	`static int addrconf_disable_ipv6(struct ctl_table table, int p, int newf)`