From: Jiri Pirko <jiri@resnulli.us>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: netdev@vger.kernel.org, jiri@mellanox.com,
jakub.kicinski@netronome.com, jhs@mojatatu.com
Subject: Re: [Patch net v3 2/3] net_sched: fix reference counting of tc filter chain
Date: Tue, 12 Sep 2017 12:43:12 +0200 [thread overview]
Message-ID: <20170912104312.GF2036@nanopsycho> (raw)
In-Reply-To: <20170911233332.7594-3-xiyou.wangcong@gmail.com>
Tue, Sep 12, 2017 at 01:33:31AM CEST, xiyou.wangcong@gmail.com wrote:
>This patch fixes the following ugliness of tc filter chain refcnt:
>
>a) tp proto should hold a refcnt to the chain too. This significantly
> simplifies the logic.
>
>b) Chain 0 is no longer special, it is created with refcnt=1 like any
> other chains. All the ugliness in tcf_chain_put() can be gone!
>
>c) No need to handle the flushing oddly, because block still holds
> chain 0, it can not be released, this guarantees block is the last
> user.
>
>d) The race condition with RCU callbacks is easier to handle with just
> a rcu_barrier(). Much easier to understand, nothing to hide. Thanks
> to the previous patch. Please see also the comments in code.
>
>e) Make the code understandable by humans, much less error-prone.
>
>Fixes: 744a4cf63e52 ("net: sched: fix use after free when tcf_chain_destroy is called multiple times")
>Fixes: 5bc1701881e3 ("net: sched: introduce multichain support for filters")
>Cc: Jiri Pirko <jiri@mellanox.com>
>Cc: Jamal Hadi Salim <jhs@mojatatu.com>
>Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Looking good to me. Thanks!
Acked-by: Jiri Pirko <jiri@mellanox.com>
next prev parent reply other threads:[~2017-09-12 10:43 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-11 23:33 [Patch net v3 0/3] net_sched: fix filter chain reference counting Cong Wang
2017-09-11 23:33 ` [Patch net v3 1/3] net_sched: get rid of tcfa_rcu Cong Wang
2017-09-12 9:42 ` Jiri Pirko
2017-09-12 10:40 ` Jiri Pirko
2017-09-12 21:10 ` Cong Wang
2017-09-12 21:36 ` Jiri Pirko
2017-09-12 21:53 ` Cong Wang
2017-09-13 6:13 ` Jiri Pirko
2017-09-11 23:33 ` [Patch net v3 2/3] net_sched: fix reference counting of tc filter chain Cong Wang
2017-09-12 10:43 ` Jiri Pirko [this message]
2017-09-11 23:33 ` [Patch net v3 3/3] net_sched: carefully handle tcf_block_put() Cong Wang
2017-09-12 10:43 ` Jiri Pirko
2017-09-13 3:41 ` [Patch net v3 0/3] net_sched: fix filter chain reference counting David Miller
2017-09-13 6:13 ` Jiri Pirko
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