Date: Wed, 9 Apr 2014 18:09:53 -0700 From: Adrian Chadd <adrian@freebsd.org> To: Karim Fodil-Lemelin <fodillemlinkarim@gmail.com> Cc: FreeBSD Net <freebsd-net@freebsd.org> Subject: Re: Preventing ng_callout() timeouts to trigger packet queuing Message-ID: <CAJ-VmomsK%2BOYdFCzedSaVCCzvu97zUthbNhYFivgAK8eN5Tnvg@mail.gmail.com> In-Reply-To: <5345BAE7.4010501@gmail.com> References: <53459C96.5040304@gmail.com> <5345BAE7.4010501@gmail.com>
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Hi!
Would you mind filing a PR for this?
www.freebsd.org/send-pr.html
That way it won't (hopefully!) get lost.
Thanks!
-a
On 9 April 2014 14:25, Karim Fodil-Lemelin <fodillemlinkarim@gmail.com> wrote:
> Hi,
>
> Below is a revised patch for this issue. It accounts for nodes or hooks that
> explicitly need to be queuing:
>
> @@ -3632,7 +3632,12 @@ ng_callout(struct callout *c, node_p node, hook_p
> hook, int ticks,
>
> if ((item = ng_alloc_item(NGQF_FN, NG_NOFLAGS)) == NULL)
> return (ENOMEM);
>
> - item->el_flags |= NGQF_WRITER;
> + if ((node->nd_flags & NGF_FORCE_WRITER) ||
> + (hook && (hook->hk_flags & HK_FORCE_WRITER)))
>
> + item->el_flags |= NGQF_WRITER;
> + else
>
> + item->el_flags |= NGQF_READER;
> +
> NG_NODE_REF(node); /* and one for the item */
> NGI_SET_NODE(item, node);
> if (hook) {
>
> Regards,
>
> Karim.
>
>
> On 09/04/2014 3:16 PM, Karim Fodil-Lemelin wrote:
>>
>> Hi List,
>>
>> I'm calling out to the general wisdom ... I have seen an issue in netgraph
>> where, if called, a callout routine registered by ng_callout() will trigger
>> packet queuing inside the worklist of netgraph since ng_callout() makes my
>> node suddenly a WRITER node (therefore non reentrant) for the duration of
>> the call.
>>
>> So as soon as the callout function returns, all following packets will get
>> directly passed to the node again and when the ngintr thread gets executed
>> then only then will I get the queued packets. This introduces out of order
>> packets in the flow. I am using the current patch below to solve the issue
>> and I am wondering if there is anything wrong with it (and maybe contribute
>> back :):
>>
>>
>> @@ -3632,7 +3632,7 @@ ng_callout(struct callout *c, node_p node, hook_p
>> hook, int ticks,
>> if ((item = ng_alloc_item(NGQF_FN, NG_NOFLAGS)) == NULL)
>> return (ENOMEM);
>>
>> - item->el_flags |= NGQF_WRITER;
>> + item->el_flags = NGQF_READER;
>> NG_NODE_REF(node); /* and one for the item */
>> NGI_SET_NODE(item, node);
>> if (hook) {
>>
>>
>> Best regards,
>>
>> Karim.
>> _______________________________________________
>> freebsd-net@freebsd.org mailing list
>> http://lists.freebsd.org/mailman/listinfo/freebsd-net
>> To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org"
>
>
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