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SubjectRe: INFO: rcu detected stall in br_handle_frame (2)
Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On 12/28/19 3:15 AM, Florian Westphal wrote:
> > If you don't have a better idea/suggestion for an upperlimit INT_MAX
> > would be enough to prevent perpetual <= 0 condition.
>
> Thanks Florian for the analysis.
>
> I guess we could use a conservative upper bound value of (1 << 20)
> ( about 16 64KB packets )
>
> diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
> index ff4c5e9d0d7778d86f20f4bd67cc627eed0713d9..12f1d1c6044fac9db987f7ce3a50a7e2c711358b 100644
> --- a/net/sched/sch_fq.c
> +++ b/net/sched/sch_fq.c
> @@ -786,15 +786,20 @@ static int fq_change(struct Qdisc *sch, struct nlattr *opt,
> if (tb[TCA_FQ_QUANTUM]) {
> u32 quantum = nla_get_u32(tb[TCA_FQ_QUANTUM]);
>
> - if (quantum > 0)
> + if (quantum > 0 && quantum <= (1 << 20))
> q->quantum = quantum;
> else
> err = -EINVAL;
> }
>
> - if (tb[TCA_FQ_INITIAL_QUANTUM])
> - q->initial_quantum = nla_get_u32(tb[TCA_FQ_INITIAL_QUANTUM]);
> + if (tb[TCA_FQ_INITIAL_QUANTUM]) {
> + u32 quantum = nla_get_u32(tb[TCA_FQ_INITIAL_QUANTUM]);
>
> + if (quantum > 0 && quantum <= (1 << 20))
> + q->initial_quantum = quantum;
> + else
> + err = -EINVAL;
> + }
> if (tb[TCA_FQ_FLOW_DEFAULT_RATE])
> pr_warn_ratelimited("sch_fq: defrate %u ignored.\n",
> nla_get_u32(tb[TCA_FQ_FLOW_DEFAULT_RATE]));
>

Perhaps it would make sense to add an #ifdef for the 1 << 20 and
a small comment as to what this is / where this comes from.

But other than that nit, this looks good to me, thanks Eric!

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