From: Jamal Hadi Salim <jhs@mojatatu•com>
To: John Fastabend <john.fastabend@gmail•com>,
xiyou.wangcong@gmail•com, davem@davemloft•net,
eric.dumazet@gmail•com
Cc: netdev@vger•kernel.org
Subject: Re: [net-next PATCH 2/2] net: sched: cls_u32 changes to knode must appear atomic to readers
Date: Thu, 18 Sep 2014 07:38:13 -0400 [thread overview]
Message-ID: <541AC425.2090300@mojatatu.com> (raw)
In-Reply-To: <20140917191202.20529.87231.stgit@nitbit.x32>
On 09/17/14 15:12, John Fastabend wrote:
> Changes to the cls_u32 classifier must appear atomic to the
> readers. Before this patch if a change is requested for both
> the exts and ifindex, first the ifindex is updated then the
> exts with tcf_exts_change(). This opens a small window where
> a reader can have a exts chain with an incorrect ifindex. This
> violates the the RCU semantics.
>
> Here we resolve this by always passing u32_set_parms() a copy
> of the tc_u_knode to work on and then inserting it into the hash
> table after the updates have been successfully applied.
>
> Tested with the following short script:
>
>
> #tc filter add dev p3p2 parent 8001:0 protocol ip prio 99 handle 1: \
> u32 divisor 256
>
> #tc filter add dev p3p2 parent 8001:0 protocol ip prio 99 \
> u32 link 1: hashkey mask ffffff00 at 12 \
> match ip src 192.168.8.0/2
>
> #tc filter add dev p3p2 parent 8001:0 protocol ip prio 102 \
> handle 1::10 u32 classid 1:2 ht 1: \
> match ip src 192.168.8.0/8 match ip tos 0x0a 1e
>
> #tc filter change dev p3p2 parent 8001:0 protocol ip prio 102 \
> handle 1::10 u32 classid 1:2 ht 1: \
> match ip src 1.1.0.0/8 match ip tos 0x0b 1e
>
> CC: Eric Dumazet <edumazet@google•com>
> CC: Jamal Hadi Salim <jhs@mojatatu•com>
> Signed-off-by: John Fastabend <john.r.fastabend@intel•com>
Looks good to me.
Acked-by: Jamal Hadi Salim <jhs@mojatatu•com>
cheers,
jamal
next prev parent reply other threads:[~2014-09-18 11:38 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-17 19:11 [net-next PATCH 1/2] net: cls_u32: fix missed pcpu_success free_percpu John Fastabend
2014-09-17 19:12 ` [net-next PATCH 2/2] net: sched: cls_u32 changes to knode must appear atomic to readers John Fastabend
2014-09-17 21:11 ` Cong Wang
2014-09-18 0:06 ` John Fastabend
2014-09-18 16:28 ` Cong Wang
2014-09-18 16:39 ` John Fastabend
2014-09-18 11:38 ` Jamal Hadi Salim [this message]
2014-09-20 4:55 ` John Fastabend
2014-09-18 1:17 ` [net-next PATCH 1/2] net: cls_u32: fix missed pcpu_success free_percpu John Fastabend
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