From mboxrd@z Thu Jan  1 00:00:00 1970
From: Cong Wang <xiyou.wangcong@gmail.com>
Subject: Re: [PATCHv2 ipsec-next] xfrm: Namespacify xfrm_policy_sk_bundles
Date: Wed, 18 Dec 2013 05:33:58 +0000 (UTC)
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On Wed, 18 Dec 2013 at 04:50 GMT, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On Wed, 2013-12-18 at 11:34 +0800, Fan Du wrote:
>> -
>> -			spin_lock_bh(&net->xfrm.xfrm_policy_sk_bundle_lock);
>> -			xdst->u.dst.next = xfrm_policy_sk_bundles;
>> -			xfrm_policy_sk_bundles = &xdst->u.dst;
>> -			spin_unlock_bh(&net->xfrm.xfrm_policy_sk_bundle_lock);
>> -
>> +			xdst->u.dst.next = xchg(&net->xfrm.xfrm_policy_sk_bundles,
>> +						&xdst->u.dst);
>
> This is not safe.
>
> Take a look at include/linux/llist.h if you really want to avoid the
> spinlock.
>

Exactly, xfrm_policy_sk_bundles list is only traversed after deletion.