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SubjectRe: net: rcu warnings in ip6fl_get_first
On Thu, Feb 7, 2013 at 8:38 PM, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> On Thu, 07 Feb 2013 at 19:32 GMT, Sasha Levin <sasha.levin@oracle.com> wrote:
>> Hi guys,
>>
>> I got the following while fuzzing with trinity inside a KVM tools guest:
>>
>> [ 51.680236] ===============================
>> [ 51.681914] [ INFO: suspicious RCU usage. ]
>> [ 51.683610] 3.8.0-rc6-next-20130206-sasha-00028-g83214f7-dirty #276 Tainted: G W
>> [ 51.686703] -------------------------------
>> [ 51.688281] net/ipv6/ip6_flowlabel.c:671 suspicious rcu_dereference_check() usage!
>> [ 51.691345]
>
> It should use rcu_dereference_bh()...
>
> diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c
> index ea42bf4..c50080f 100644
> --- a/net/ipv6/ip6_flowlabel.c
> +++ b/net/ipv6/ip6_flowlabel.c
> @@ -65,13 +65,13 @@ static DEFINE_SPINLOCK(ip6_fl_lock);
> static DEFINE_SPINLOCK(ip6_sk_fl_lock);
>
> #define for_each_fl_rcu(hash, fl) \
> - for (fl = rcu_dereference(fl_ht[(hash)]); \
> + for (fl = rcu_dereference_bh(fl_ht[(hash)]); \
> fl != NULL; \
> - fl = rcu_dereference(fl->next))
> + fl = rcu_dereference_hb(fl->next))
> #define for_each_fl_continue_rcu(fl) \
> - for (fl = rcu_dereference(fl->next); \
> + for (fl = rcu_dereference_bh(fl->next); \
> fl != NULL; \
> - fl = rcu_dereference(fl->next))
> + fl = rcu_dereference_bh(fl->next))
>
> #define for_each_sk_fl_rcu(np, sfl) \
> for (sfl = rcu_dereference_bh(np->ipv6_fl_list); \

Yup, that's how I fixed it locally and it was running without warnings
for couple of hours now.


Thanks,
Sasha


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