Subject: Re: [WARNING net-next] from ixgbe_configure

From: John Fastabend <[email-masked]>
Date: Sun, 29 Dec 2013 21:29:37 -0800

On 12/29/2013 01:15 PM, Stephen Hemminger wrote:
> Warning with current net-next from ixgbe_configure calling
> netdev_all_upper_get_next_dev_rcu without RCU read lock held.
>
>
> [    4.717512] r8169 0000:03:00.0 eth0: link down
> [    4.717581] r8169 0000:03:00.0 eth0: link down
> [    4.717590] IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready
> [    6.722390] r8169 0000:03:00.0 eth0: link up
> [    6.722428] IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready
> [    9.833968] ------------[ cut here ]------------
> [    9.833976] WARNING: CPU: 5 PID: 2173 at net/core/dev.c:4448 netdev_all_upper_get_next_dev_rcu+0x6b/0xa0()

This should be fixed when net is synced with net-next by the
following commit,

author		John Fastabend <[email-masked]>
committer	Jeff Kirsher <[email-masked]>
commit		85328240c625f322af9f69c7b60e619717101d77

net: allow netdev_all_upper_get_next_dev_rcu with rtnl lock held

It is useful to be able to walk all upper devices when bringing a device 
online where the RTNL lock is held. In this case it is safe to walk the 
all_adj_list because the RTNL lock is used to protect the write side as 
well.
[...]

Thanks,
John

-- 
John Fastabend         Intel Corporation

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