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* [PATCH] ipv6: addrconf: Avoid addrconf_disable_change() using RCU read-side lock
@ 2017-01-19  8:26 Kefeng Wang
  2017-01-19 16:09 ` David Miller
  0 siblings, 1 reply; 2+ messages in thread
From: Kefeng Wang @ 2017-01-19  8:26 UTC (permalink / raw)
  To: David S. Miller, Alexey Kuznetsov, James Morris,
	Hideaki YOSHIFUJI, Patrick McHardy, netdev
  Cc: linux-kernel, dingtianhong, weiyongjun1, guohanjun, Kefeng Wang

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>
---
 net/ipv6/addrconf.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index c1e124b..f60e88e 100644
--- 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)
-- 
1.7.12.4

^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH] ipv6: addrconf: Avoid addrconf_disable_change() using RCU read-side lock
  2017-01-19  8:26 [PATCH] ipv6: addrconf: Avoid addrconf_disable_change() using RCU read-side lock Kefeng Wang
@ 2017-01-19 16:09 ` David Miller
  0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2017-01-19 16:09 UTC (permalink / raw)
  To: wangkefeng.wang
  Cc: kuznet, jmorris, yoshfuji, kaber, netdev, linux-kernel,
	dingtianhong, weiyongjun1, guohanjun

From: Kefeng Wang <wangkefeng.wang@huawei.com>
Date: Thu, 19 Jan 2017 16:26:21 +0800

> 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>

Applied and queued up for -stable, thanks.

^ permalink raw reply	[flat|nested] 2+ messages in thread

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2017-01-19  8:26 [PATCH] ipv6: addrconf: Avoid addrconf_disable_change() using RCU read-side lock Kefeng Wang
2017-01-19 16:09 ` David Miller

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