From: John Fastabend <john.fastabend@gmail•com>
To: Eric Dumazet <eric.dumazet@gmail•com>
Cc: xiyou.wangcong@gmail•com, davem@davemloft•net, jhs@mojatatu•com,
netdev@vger•kernel.org, paulmck@linux•vnet.ibm.com,
brouer@redhat•com
Subject: Re: [net-next PATCH v3 07/15] net: sched: RCU cls_route
Date: Tue, 09 Sep 2014 09:24:02 -0700 [thread overview]
Message-ID: <540F29A2.8050805@gmail.com> (raw)
In-Reply-To: <1410267553.11872.167.camel@edumazet-glaptop2.roam.corp.google.com>
On 09/09/2014 05:59 AM, Eric Dumazet wrote:
> On Mon, 2014-09-08 at 22:57 -0700, John Fastabend wrote:
>> RCUify the route classifier. For now however spinlock's are used to
>> protect fastmap cache.
>>
>> The issue here is the fastmap may be read by one CPU while the
>> cache is being updated by another. An array of pointers could be
>> one possible solution.
>
> Yep, this doesnt seem like an urgent issue anyway.
>
>>
>> Signed-off-by: John Fastabend <john.r.fastabend@intel•com>
>> ---
[...]
>> @@ -296,27 +324,35 @@ static int route4_delete(struct tcf_proto *tp, unsigned long arg)
>> h = f->handle;
>> b = f->bkt;
>>
>> - for (fp = &b->ht[from_hash(h >> 16)]; *fp; fp = &(*fp)->next) {
>> - if (*fp == f) {
>> - tcf_tree_lock(tp);
>> + fp = &b->ht[from_hash(h >> 16)];
>> + for (nf = rtnl_dereference(*fp); nf;
>> + fp = &nf->next, nf = rtnl_dereference(*fp)) {
>> + if (nf == f) {
>> + /* unlink it */
>> *fp = f->next;
>
> Strange you left this without annotations, while rest of your patches
> always use rcu_assign_pointer(*fp, rtnl_dereference(f->next)
>
> Note that it is absolutely fine to use *fp = f->next;
>
> ;)
>
I was just trying to be explicit in the other cases although I
chose rcu_assign_pointer in many cases instead of INIT_POINTER. So for
consistency I'll make this,
RCU_INIT_POINTER(*fp, rtnl_dereference(f->next))
I also thought that sparse would warn about not wrapping f->next in
rtnl_dereference, but apparently that is not the case.
>> - tcf_tree_unlock(tp);
>>
>
>
>
--
John Fastabend Intel Corporation
next prev parent reply other threads:[~2014-09-09 16:24 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-09 5:53 [net-next PATCH v3 00/15] net/sched use rcu filters John Fastabend
2014-09-09 5:54 ` [net-next PATCH v3 01/15] net: qdisc: use rcu prefix and silence sparse warnings John Fastabend
2014-09-09 12:05 ` Eric Dumazet
2014-09-09 5:54 ` [net-next PATCH v3 02/15] net: rcu-ify tcf_proto John Fastabend
2014-09-09 12:20 ` Eric Dumazet
2014-09-09 15:15 ` John Fastabend
2014-09-09 15:20 ` Eric Dumazet
2014-09-09 5:55 ` [net-next PATCH v3 03/15] net: sched: cls_basic use RCU John Fastabend
2014-09-09 12:29 ` Eric Dumazet
2014-09-09 5:55 ` [net-next PATCH v3 04/15] net: sched: cls_cgroup " John Fastabend
2014-09-09 12:34 ` Eric Dumazet
2014-09-09 5:56 ` [net-next PATCH v3 05/15] net: sched: cls_flow " John Fastabend
2014-09-09 12:41 ` Eric Dumazet
2014-09-09 16:09 ` John Fastabend
2014-09-09 16:20 ` Eric Dumazet
2014-09-09 5:56 ` [net-next PATCH v3 06/15] net: sched: fw " John Fastabend
2014-09-09 12:48 ` Eric Dumazet
2014-09-09 5:57 ` [net-next PATCH v3 07/15] net: sched: RCU cls_route John Fastabend
2014-09-09 12:59 ` Eric Dumazet
2014-09-09 16:24 ` John Fastabend [this message]
2014-09-09 5:57 ` [net-next PATCH v3 08/15] net: sched: RCU cls_tcindex John Fastabend
2014-09-09 5:58 ` [net-next PATCH v3 09/15] net: sched: make cls_u32 lockless John Fastabend
2014-09-09 13:20 ` Eric Dumazet
2014-09-09 16:35 ` John Fastabend
2014-09-09 18:02 ` Cong Wang
2014-09-10 4:53 ` John Fastabend
2014-09-09 5:58 ` [net-next PATCH v3 10/15] net: sched: rcu'ify cls_rsvp John Fastabend
2014-09-09 13:27 ` Eric Dumazet
2014-09-09 16:46 ` John Fastabend
2014-09-09 5:59 ` [net-next PATCH v3 11/15] net: sched: rcu'ify cls_bpf John Fastabend
2014-09-09 5:59 ` [net-next PATCH v3 12/15] net: sched: make tc_action safe to walk under RCU John Fastabend
2014-09-09 6:00 ` [net-next PATCH v3 13/15] net: sched: make bstats per cpu and estimator RCU safe John Fastabend
2014-09-09 6:00 ` [net-next PATCH v3 14/15] net: sched: make qstats per cpu John Fastabend
2014-09-09 6:01 ` [net-next PATCH v3 15/15] net: sched: drop ingress qdisc lock John Fastabend
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