From 13a9965de32457d59aa3162d657aa4c5e512c146 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 18 Apr 2024 07:32:44 +0000 Subject: [PATCH] net_sched: sch_fq_pie: implement lockless fq_pie_dump() Instead of relying on RTNL, fq_pie_dump() can use READ_ONCE() annotations, paired with WRITE_ONCE() ones in fq_pie_change(). Signed-off-by: Eric Dumazet Reviewed-by: Simon Horman Signed-off-by: David S. Miller --- net/sched/sch_fq_pie.c | 61 +++++++++++++++++++++++------------------- 1 file changed, 34 insertions(+), 27 deletions(-) diff --git a/net/sched/sch_fq_pie.c b/net/sched/sch_fq_pie.c index 358cf304f4c9..c38f33ff80bd 100644 --- a/net/sched/sch_fq_pie.c +++ b/net/sched/sch_fq_pie.c @@ -299,8 +299,8 @@ static int fq_pie_change(struct Qdisc *sch, struct nlattr *opt, if (tb[TCA_FQ_PIE_LIMIT]) { u32 limit = nla_get_u32(tb[TCA_FQ_PIE_LIMIT]); - q->p_params.limit = limit; - sch->limit = limit; + WRITE_ONCE(q->p_params.limit, limit); + WRITE_ONCE(sch->limit, limit); } if (tb[TCA_FQ_PIE_FLOWS]) { if (q->flows) { @@ -322,39 +322,45 @@ static int fq_pie_change(struct Qdisc *sch, struct nlattr *opt, u32 target = nla_get_u32(tb[TCA_FQ_PIE_TARGET]); /* convert to pschedtime */ - q->p_params.target = - PSCHED_NS2TICKS((u64)target * NSEC_PER_USEC); + WRITE_ONCE(q->p_params.target, + PSCHED_NS2TICKS((u64)target * NSEC_PER_USEC)); } /* tupdate is in jiffies */ if (tb[TCA_FQ_PIE_TUPDATE]) - q->p_params.tupdate = - usecs_to_jiffies(nla_get_u32(tb[TCA_FQ_PIE_TUPDATE])); + WRITE_ONCE(q->p_params.tupdate, + usecs_to_jiffies(nla_get_u32(tb[TCA_FQ_PIE_TUPDATE]))); if (tb[TCA_FQ_PIE_ALPHA]) - q->p_params.alpha = nla_get_u32(tb[TCA_FQ_PIE_ALPHA]); + WRITE_ONCE(q->p_params.alpha, + nla_get_u32(tb[TCA_FQ_PIE_ALPHA])); if (tb[TCA_FQ_PIE_BETA]) - q->p_params.beta = nla_get_u32(tb[TCA_FQ_PIE_BETA]); + WRITE_ONCE(q->p_params.beta, + nla_get_u32(tb[TCA_FQ_PIE_BETA])); if (tb[TCA_FQ_PIE_QUANTUM]) - q->quantum = nla_get_u32(tb[TCA_FQ_PIE_QUANTUM]); + WRITE_ONCE(q->quantum, nla_get_u32(tb[TCA_FQ_PIE_QUANTUM])); if (tb[TCA_FQ_PIE_MEMORY_LIMIT]) - q->memory_limit = nla_get_u32(tb[TCA_FQ_PIE_MEMORY_LIMIT]); + WRITE_ONCE(q->memory_limit, + nla_get_u32(tb[TCA_FQ_PIE_MEMORY_LIMIT])); if (tb[TCA_FQ_PIE_ECN_PROB]) - q->ecn_prob = nla_get_u32(tb[TCA_FQ_PIE_ECN_PROB]); + WRITE_ONCE(q->ecn_prob, + nla_get_u32(tb[TCA_FQ_PIE_ECN_PROB])); if (tb[TCA_FQ_PIE_ECN]) - q->p_params.ecn = nla_get_u32(tb[TCA_FQ_PIE_ECN]); + WRITE_ONCE(q->p_params.ecn, + nla_get_u32(tb[TCA_FQ_PIE_ECN])); if (tb[TCA_FQ_PIE_BYTEMODE]) - q->p_params.bytemode = nla_get_u32(tb[TCA_FQ_PIE_BYTEMODE]); + WRITE_ONCE(q->p_params.bytemode, + nla_get_u32(tb[TCA_FQ_PIE_BYTEMODE])); if (tb[TCA_FQ_PIE_DQ_RATE_ESTIMATOR]) - q->p_params.dq_rate_estimator = - nla_get_u32(tb[TCA_FQ_PIE_DQ_RATE_ESTIMATOR]); + WRITE_ONCE(q->p_params.dq_rate_estimator, + nla_get_u32(tb[TCA_FQ_PIE_DQ_RATE_ESTIMATOR])); /* Drop excess packets if new limit is lower */ while (sch->q.qlen > sch->limit) { @@ -471,22 +477,23 @@ static int fq_pie_dump(struct Qdisc *sch, struct sk_buff *skb) return -EMSGSIZE; /* convert target from pschedtime to us */ - if (nla_put_u32(skb, TCA_FQ_PIE_LIMIT, sch->limit) || - nla_put_u32(skb, TCA_FQ_PIE_FLOWS, q->flows_cnt) || + if (nla_put_u32(skb, TCA_FQ_PIE_LIMIT, READ_ONCE(sch->limit)) || + nla_put_u32(skb, TCA_FQ_PIE_FLOWS, READ_ONCE(q->flows_cnt)) || nla_put_u32(skb, TCA_FQ_PIE_TARGET, - ((u32)PSCHED_TICKS2NS(q->p_params.target)) / + ((u32)PSCHED_TICKS2NS(READ_ONCE(q->p_params.target))) / NSEC_PER_USEC) || nla_put_u32(skb, TCA_FQ_PIE_TUPDATE, - jiffies_to_usecs(q->p_params.tupdate)) || - nla_put_u32(skb, TCA_FQ_PIE_ALPHA, q->p_params.alpha) || - nla_put_u32(skb, TCA_FQ_PIE_BETA, q->p_params.beta) || - nla_put_u32(skb, TCA_FQ_PIE_QUANTUM, q->quantum) || - nla_put_u32(skb, TCA_FQ_PIE_MEMORY_LIMIT, q->memory_limit) || - nla_put_u32(skb, TCA_FQ_PIE_ECN_PROB, q->ecn_prob) || - nla_put_u32(skb, TCA_FQ_PIE_ECN, q->p_params.ecn) || - nla_put_u32(skb, TCA_FQ_PIE_BYTEMODE, q->p_params.bytemode) || + jiffies_to_usecs(READ_ONCE(q->p_params.tupdate))) || + nla_put_u32(skb, TCA_FQ_PIE_ALPHA, READ_ONCE(q->p_params.alpha)) || + nla_put_u32(skb, TCA_FQ_PIE_BETA, READ_ONCE(q->p_params.beta)) || + nla_put_u32(skb, TCA_FQ_PIE_QUANTUM, READ_ONCE(q->quantum)) || + nla_put_u32(skb, TCA_FQ_PIE_MEMORY_LIMIT, + READ_ONCE(q->memory_limit)) || + nla_put_u32(skb, TCA_FQ_PIE_ECN_PROB, READ_ONCE(q->ecn_prob)) || + nla_put_u32(skb, TCA_FQ_PIE_ECN, READ_ONCE(q->p_params.ecn)) || + nla_put_u32(skb, TCA_FQ_PIE_BYTEMODE, READ_ONCE(q->p_params.bytemode)) || nla_put_u32(skb, TCA_FQ_PIE_DQ_RATE_ESTIMATOR, - q->p_params.dq_rate_estimator)) + READ_ONCE(q->p_params.dq_rate_estimator))) goto nla_put_failure; return nla_nest_end(skb, opts);