[PATCH v2] dummy: fix rcu_sched self-detected stalls

[Eric Dumazet <eric.dumazet@gmail.com>]

From: Eric Dumazet <edumazet@google.com>

Trying to "modprobe dummy numdummies=30000" triggers :

INFO: rcu_sched self-detected stall on CPU { 8} (t=60000 jiffies)

After this splat, RTNL is locked and reboot is needed.

We must call cond_resched() to avoid this, even holding RTNL.

Signed-off-by: Eric Dumazet <edumazet@google.com>
---
 drivers/net/dummy.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/dummy.c b/drivers/net/dummy.c
index 442d91a..bab0158 100644
--- a/drivers/net/dummy.c
+++ b/drivers/net/dummy.c
@@ -187,8 +187,10 @@ static int __init dummy_init_module(void)
 	rtnl_lock();
 	err = __rtnl_link_register(&dummy_link_ops);
 
-	for (i = 0; i < numdummies && !err; i++)
+	for (i = 0; i < numdummies && !err; i++) {
 		err = dummy_init_one();
+		cond_resched();
+	}
 	if (err < 0)
 		__rtnl_link_unregister(&dummy_link_ops);
 	rtnl_unlock();