dummy: fix rcu_sched self-detected stalls

BugLink: http://bugs.launchpad.net/bugs/1025406

[ Upstream commit 16b0dc29c1af9df341428f4c49ada4f626258082 ]

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>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/net/dummy.c b/drivers/net/dummy.c
index 3fa19c16211..098ff315694 100644
--- a/drivers/net/dummy.c
+++ b/drivers/net/dummy.c
@@ -37,6 +37,7 @@
 #include <linux/rtnetlink.h>
 #include <net/rtnetlink.h>
 #include <linux/u64_stats_sync.h>
+#include <linux/sched.h>
 
 static int numdummies = 1;
 
@@ -186,8 +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();