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Message-ID: <20240415132054.3822230-10-edumazet@google.com>
Date: Mon, 15 Apr 2024 13:20:49 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>
Cc: Jamal Hadi Salim <jhs@...atatu.com>, Cong Wang <xiyou.wangcong@...il.com>,
Jiri Pirko <jiri@...nulli.us>, netdev@...r.kernel.org, eric.dumazet@...il.com,
Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net-next 09/14] 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 <edumazet@...gle.com>
---
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 79f9d6de6c852268fa293f8067d029d385b54976..4f908c11ba9528f8f9f3af6752ff10005d6f6511 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;
}
--
2.44.0.683.g7961c838ac-goog
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