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From: Cong Wang <xiyou.wangcong@gmail.com>
To: John Fastabend <john.fastabend@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
	David Miller <davem@davemloft.net>,
	Linux Kernel Network Developers <netdev@vger.kernel.org>,
	Jamal Hadi Salim <jhs@mojatatu.com>,
	Hadar Hen Zion <hadarh@mellanox.com>,
	Amir Vadai <amirva@mellanox.com>
Subject: Re: [PATCH net] net_sched: act_mirred: full rcu conversion
Date: Sun, 11 Sep 2016 23:12:04 -0700	[thread overview]
Message-ID: <CAM_iQpXycdn9_LW_qYzUe5T97ABOj3KrivjCB5ho9wbKeFR0MQ@mail.gmail.com> (raw)
In-Reply-To: <57D2DAD1.5000306@gmail.com>

On Fri, Sep 9, 2016 at 8:52 AM, John Fastabend <john.fastabend@gmail.com> wrote:
> On 16-09-08 10:26 PM, Cong Wang wrote:
>> On Thu, Sep 8, 2016 at 8:51 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
>>> On Thu, 2016-09-08 at 08:47 -0700, John Fastabend wrote:
>>>
>>>> Works for me. FWIW I find this plenty straightforward and don't really
>>>> see the need to make the hash table itself rcu friendly.
>>>>
>>>> Acked-by: John Fastabend <john.r.fastabend@intel.com>
>>>>
>>>
>>> Yes, it seems this hash table is used in control path, with RTNL held
>>> anyway.
>>
>> Seriously? You never read hashtable in fast path?? I think you need
>> to wake up.
>>
>
> But the actions use refcnt'ing and should never be decremented to zero
> as long as they can still be referenced by an active filter. If each
> action handles its parameters like mirred/gact then I don't see why its
> necessary.

This is correct, by "read" I meant "dereference", the tc actions
are now permanently stored in hashtable directly, so "reading"
a tc action is reading from hashtable.

Sorry if this wasn't clear.

  reply	other threads:[~2016-09-12  6:12 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-09-02  5:57 [RFC Patch net-next 0/6] net_sched: really switch to RCU for tc actions Cong Wang
2016-09-02  5:57 ` [RFC Patch net-next 1/6] net_sched: use RCU for action hash table Cong Wang
2016-09-06 12:47   ` Jamal Hadi Salim
2016-09-06 22:37     ` Cong Wang
2016-09-02  5:57 ` [RFC Patch net-next 2/6] net_sched: introduce tcf_hash_replace() Cong Wang
2016-09-06 12:52   ` Jamal Hadi Salim
2016-09-06 22:34     ` Cong Wang
2016-09-02  5:57 ` [RFC Patch net-next 3/6] net_sched: return NULL in tcf_hash_check() Cong Wang
2016-09-02  5:57 ` [RFC Patch net-next 4/6] net_sched: introduce tcf_hash_copy() Cong Wang
2016-09-02  5:57 ` [RFC Patch net-next 5/6] net_sched: use rcu in fast path Cong Wang
2016-09-06 14:52   ` Eric Dumazet
2016-09-08  6:04     ` John Fastabend
2016-09-08 13:28       ` Eric Dumazet
2016-09-08 15:35         ` [PATCH net] net_sched: act_mirred: full rcu conversion Eric Dumazet
2016-09-08 15:47           ` John Fastabend
2016-09-08 15:51             ` Eric Dumazet
2016-09-09  5:26               ` Cong Wang
2016-09-09 12:23                 ` Eric Dumazet
2016-09-09 15:52                 ` John Fastabend
2016-09-12  6:12                   ` Cong Wang [this message]
2016-09-12 15:34                     ` John Fastabend
2016-09-09  5:24           ` Cong Wang
2016-09-09  5:48             ` Alexei Starovoitov
2016-09-09  5:59               ` Cong Wang
2016-09-09 12:25                 ` Eric Dumazet
2016-09-09 12:23             ` Eric Dumazet
2016-09-12  5:46               ` Cong Wang
2016-09-08 15:49         ` [RFC Patch net-next 5/6] net_sched: use rcu in fast path John Fastabend
2016-09-09  5:54           ` Cong Wang
2016-09-09 15:25             ` John Fastabend
2016-09-09  5:49     ` Cong Wang
2016-09-02  5:57 ` [RFC Patch net-next 6/6] net_sched: switch to RCU API for act_mirred Cong Wang
2016-09-02  7:09 ` [RFC Patch net-next 0/6] net_sched: really switch to RCU for tc actions Jiri Pirko
2016-09-02 19:44   ` Cong Wang
2016-09-07 16:23 ` John Fastabend
2016-09-08  6:05   ` John Fastabend
2016-09-09  5:22   ` Cong Wang

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