From 396a0038508aa7e380e317a80cc905b794e83191 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Thu, 18 Apr 2024 07:32:43 +0000 Subject: [PATCH] net_sched: sch_fq_codel: implement lockless fq_codel_dump() Instead of relying on RTNL, fq_codel_dump() can use READ_ONCE() annotations, paired with WRITE_ONCE() ones in fq_codel_change(). Signed-off-by: Eric Dumazet Reviewed-by: Simon Horman Signed-off-by: David S. Miller --- net/sched/sch_fq_codel.c | 57 ++++++++++++++++++++++++---------------- 1 file changed, 35 insertions(+), 22 deletions(-) diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c index 79f9d6de6c85..4f908c11ba95 100644 --- a/net/sched/sch_fq_codel.c +++ b/net/sched/sch_fq_codel.c @@ -396,40 +396,49 @@ static int fq_codel_change(struct Qdisc *sch, struct nlattr *opt, if (tb[TCA_FQ_CODEL_TARGET]) { u64 target = nla_get_u32(tb[TCA_FQ_CODEL_TARGET]); - q->cparams.target = (target * NSEC_PER_USEC) >> CODEL_SHIFT; + WRITE_ONCE(q->cparams.target, + (target * NSEC_PER_USEC) >> CODEL_SHIFT); } if (tb[TCA_FQ_CODEL_CE_THRESHOLD]) { u64 val = nla_get_u32(tb[TCA_FQ_CODEL_CE_THRESHOLD]); - q->cparams.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT; + WRITE_ONCE(q->cparams.ce_threshold, + (val * NSEC_PER_USEC) >> CODEL_SHIFT); } if (tb[TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR]) - q->cparams.ce_threshold_selector = nla_get_u8(tb[TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR]); + WRITE_ONCE(q->cparams.ce_threshold_selector, + nla_get_u8(tb[TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR])); if (tb[TCA_FQ_CODEL_CE_THRESHOLD_MASK]) - q->cparams.ce_threshold_mask = nla_get_u8(tb[TCA_FQ_CODEL_CE_THRESHOLD_MASK]); + WRITE_ONCE(q->cparams.ce_threshold_mask, + nla_get_u8(tb[TCA_FQ_CODEL_CE_THRESHOLD_MASK])); if (tb[TCA_FQ_CODEL_INTERVAL]) { u64 interval = nla_get_u32(tb[TCA_FQ_CODEL_INTERVAL]); - q->cparams.interval = (interval * NSEC_PER_USEC) >> CODEL_SHIFT; + WRITE_ONCE(q->cparams.interval, + (interval * NSEC_PER_USEC) >> CODEL_SHIFT); } if (tb[TCA_FQ_CODEL_LIMIT]) - sch->limit = nla_get_u32(tb[TCA_FQ_CODEL_LIMIT]); + WRITE_ONCE(sch->limit, + nla_get_u32(tb[TCA_FQ_CODEL_LIMIT])); if (tb[TCA_FQ_CODEL_ECN]) - q->cparams.ecn = !!nla_get_u32(tb[TCA_FQ_CODEL_ECN]); + WRITE_ONCE(q->cparams.ecn, + !!nla_get_u32(tb[TCA_FQ_CODEL_ECN])); if (quantum) - q->quantum = quantum; + WRITE_ONCE(q->quantum, quantum); if (tb[TCA_FQ_CODEL_DROP_BATCH_SIZE]) - q->drop_batch_size = max(1U, nla_get_u32(tb[TCA_FQ_CODEL_DROP_BATCH_SIZE])); + WRITE_ONCE(q->drop_batch_size, + max(1U, nla_get_u32(tb[TCA_FQ_CODEL_DROP_BATCH_SIZE]))); if (tb[TCA_FQ_CODEL_MEMORY_LIMIT]) - q->memory_limit = min(1U << 31, nla_get_u32(tb[TCA_FQ_CODEL_MEMORY_LIMIT])); + WRITE_ONCE(q->memory_limit, + min(1U << 31, nla_get_u32(tb[TCA_FQ_CODEL_MEMORY_LIMIT]))); while (sch->q.qlen > sch->limit || q->memory_usage > q->memory_limit) { @@ -522,6 +531,7 @@ static int fq_codel_init(struct Qdisc *sch, struct nlattr *opt, static int fq_codel_dump(struct Qdisc *sch, struct sk_buff *skb) { struct fq_codel_sched_data *q = qdisc_priv(sch); + codel_time_t ce_threshold; struct nlattr *opts; opts = nla_nest_start_noflag(skb, TCA_OPTIONS); @@ -529,30 +539,33 @@ static int fq_codel_dump(struct Qdisc *sch, struct sk_buff *skb) goto nla_put_failure; if (nla_put_u32(skb, TCA_FQ_CODEL_TARGET, - codel_time_to_us(q->cparams.target)) || + codel_time_to_us(READ_ONCE(q->cparams.target))) || nla_put_u32(skb, TCA_FQ_CODEL_LIMIT, - sch->limit) || + READ_ONCE(sch->limit)) || nla_put_u32(skb, TCA_FQ_CODEL_INTERVAL, - codel_time_to_us(q->cparams.interval)) || + codel_time_to_us(READ_ONCE(q->cparams.interval))) || nla_put_u32(skb, TCA_FQ_CODEL_ECN, - q->cparams.ecn) || + READ_ONCE(q->cparams.ecn)) || nla_put_u32(skb, TCA_FQ_CODEL_QUANTUM, - q->quantum) || + READ_ONCE(q->quantum)) || nla_put_u32(skb, TCA_FQ_CODEL_DROP_BATCH_SIZE, - q->drop_batch_size) || + READ_ONCE(q->drop_batch_size)) || nla_put_u32(skb, TCA_FQ_CODEL_MEMORY_LIMIT, - q->memory_limit) || + READ_ONCE(q->memory_limit)) || nla_put_u32(skb, TCA_FQ_CODEL_FLOWS, - q->flows_cnt)) + READ_ONCE(q->flows_cnt))) goto nla_put_failure; - if (q->cparams.ce_threshold != CODEL_DISABLED_THRESHOLD) { + ce_threshold = READ_ONCE(q->cparams.ce_threshold); + if (ce_threshold != CODEL_DISABLED_THRESHOLD) { if (nla_put_u32(skb, TCA_FQ_CODEL_CE_THRESHOLD, - codel_time_to_us(q->cparams.ce_threshold))) + codel_time_to_us(ce_threshold))) goto nla_put_failure; - if (nla_put_u8(skb, TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR, q->cparams.ce_threshold_selector)) + if (nla_put_u8(skb, TCA_FQ_CODEL_CE_THRESHOLD_SELECTOR, + READ_ONCE(q->cparams.ce_threshold_selector))) goto nla_put_failure; - if (nla_put_u8(skb, TCA_FQ_CODEL_CE_THRESHOLD_MASK, q->cparams.ce_threshold_mask)) + if (nla_put_u8(skb, TCA_FQ_CODEL_CE_THRESHOLD_MASK, + READ_ONCE(q->cparams.ce_threshold_mask))) goto nla_put_failure; }