ifb: fix rcu_sched self-detected stalls

[ Upstream commit 440d57bc5ff55ec1efb3efc9cbe9420b4bbdfefa ]

According to the commit 16b0dc29c1af9df341428f4c49ada4f626258082
(dummy: fix rcu_sched self-detected stalls)

Eric Dumazet fix the problem in dummy, but the ifb will occur the
same problem like the dummy modules.

Trying to "modprobe ifb numifbs=30000" triggers :

INFO: rcu_sched self-detected stall on CPU

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

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

Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/net/ifb.c b/drivers/net/ifb.c
index dc9f6a45515d..a11f7a45cb5f 100644
--- a/drivers/net/ifb.c
+++ b/drivers/net/ifb.c
@@ -292,8 +292,10 @@ static int __init ifb_init_module(void)
         rtnl_lock();
         err = __rtnl_link_register(&ifb_link_ops);
 
-        for (i = 0; i < numifbs && !err; i++)
+        for (i = 0; i < numifbs && !err; i++) {
                 err = ifb_init_one(i);
+                cond_resched();
+        }
         if (err)
                 __rtnl_link_unregister(&ifb_link_ops);
         rtnl_unlock();