[PATCH 056/106] ifb: fix rcu_sched self-detected stalls

From: Luis Henriques
Date: Tue Jul 30 2013 - 05:33:31 EST -stable review patch. If anyone has any objections, please let me know.


From: dingtianhong <dingtianhong@xxxxxxxxxx>

commit 440d57bc5ff55ec1efb3efc9cbe9420b4bbdfefa upstream.

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@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
drivers/net/ifb.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ifb.c b/drivers/net/ifb.c
index 344dceb..04ab337 100644
--- a/drivers/net/ifb.c
+++ b/drivers/net/ifb.c
@@ -291,8 +291,10 @@ static int __init ifb_init_module(void)
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)

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