netdev - Re: [PATCH net-next v4 07/17] net: sched: protect filter_chain list with filter_chain

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Date:   Mon, 18 Feb 2019 11:06:00 +0000
From:   Vlad Buslov <vladbu@...lanox.com>
To:     Cong Wang <xiyou.wangcong@...il.com>
CC:     Linux Kernel Network Developers <netdev@...r.kernel.org>,
        Jamal Hadi Salim <jhs@...atatu.com>,
        Jiri Pirko <jiri@...nulli.us>,
        David Miller <davem@...emloft.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>
Subject: Re: [PATCH net-next v4 07/17] net: sched: protect filter_chain list
 with filter_chain_lock mutex

On Fri 15 Feb 2019 at 22:35, Cong Wang <xiyou.wangcong@...il.com> wrote:
> On Mon, Feb 11, 2019 at 12:56 AM Vlad Buslov <vladbu@...lanox.com> wrote:
>> +#ifdef CONFIG_PROVE_LOCKING
>> +static inline bool lockdep_tcf_chain_is_locked(struct tcf_chain *chain)
>> +{
>> +       return lockdep_is_held(&chain->filter_chain_lock);
>> +}
>> +#else
>> +static inline bool lockdep_tcf_chain_is_locked(struct tcf_block *chain)
>> +{
>> +       return true;
>> +}
>> +#endif /* #ifdef CONFIG_PROVE_LOCKING */
>> +
>> +#define tcf_chain_dereference(p, chain)                                        \
>> +       rcu_dereference_protected(p, lockdep_tcf_chain_is_locked(chain))
>
>
> Are you sure you need this #ifdef CONFIG_PROVE_LOCKING?
> rcu_dereference_protected() should already test CONFIG_PROVE_RCU.
>
> Ditto for tcf_proto_dereference().

I implemented these macro same way as rtnl_dereference() is implemented,
which they are intended to substitute.

After removing them I get following compilation error with
CONFIG_PROVE_LOCKING disabled:

./include/net/sch_generic.h: In function ‘lockdep_tcf_chain_is_locked’:
./include/net/sch_generic.h:404:9: error: implicit declaration of function ‘lockdep_is_held’; did you mean ‘lockdep_rtnl_is_held’? [-Werror=implicit-function-declaration]
  return lockdep_is_held(&chain->filter_chain_lock);
         ^~~~~~~~~~~~~~~
         lockdep_rtnl_is_held