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Message-ID: <20240415132054.3822230-6-edumazet@google.com>
Date: Mon, 15 Apr 2024 13:20:45 +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 05/14] net_sched: sch_codel: implement lockless codel_dump()
Instead of relying on RTNL, codel_dump() can use READ_ONCE()
annotations, paired with WRITE_ONCE() ones in codel_change().
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
net/sched/sch_codel.c | 29 ++++++++++++++++++-----------
1 file changed, 18 insertions(+), 11 deletions(-)
diff --git a/net/sched/sch_codel.c b/net/sched/sch_codel.c
index ecb3f164bb25b33bd662c8ee07dc1b5945fd882d..3e8d4fe4d91e3ef2b7715640f6675aa5e8e2a326 100644
--- a/net/sched/sch_codel.c
+++ b/net/sched/sch_codel.c
@@ -118,26 +118,31 @@ static int codel_change(struct Qdisc *sch, struct nlattr *opt,
if (tb[TCA_CODEL_TARGET]) {
u32 target = nla_get_u32(tb[TCA_CODEL_TARGET]);
- q->params.target = ((u64)target * NSEC_PER_USEC) >> CODEL_SHIFT;
+ WRITE_ONCE(q->params.target,
+ ((u64)target * NSEC_PER_USEC) >> CODEL_SHIFT);
}
if (tb[TCA_CODEL_CE_THRESHOLD]) {
u64 val = nla_get_u32(tb[TCA_CODEL_CE_THRESHOLD]);
- q->params.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT;
+ WRITE_ONCE(q->params.ce_threshold,
+ (val * NSEC_PER_USEC) >> CODEL_SHIFT);
}
if (tb[TCA_CODEL_INTERVAL]) {
u32 interval = nla_get_u32(tb[TCA_CODEL_INTERVAL]);
- q->params.interval = ((u64)interval * NSEC_PER_USEC) >> CODEL_SHIFT;
+ WRITE_ONCE(q->params.interval,
+ ((u64)interval * NSEC_PER_USEC) >> CODEL_SHIFT);
}
if (tb[TCA_CODEL_LIMIT])
- sch->limit = nla_get_u32(tb[TCA_CODEL_LIMIT]);
+ WRITE_ONCE(sch->limit,
+ nla_get_u32(tb[TCA_CODEL_LIMIT]));
if (tb[TCA_CODEL_ECN])
- q->params.ecn = !!nla_get_u32(tb[TCA_CODEL_ECN]);
+ WRITE_ONCE(q->params.ecn,
+ !!nla_get_u32(tb[TCA_CODEL_ECN]));
qlen = sch->q.qlen;
while (sch->q.qlen > sch->limit) {
@@ -183,6 +188,7 @@ static int codel_init(struct Qdisc *sch, struct nlattr *opt,
static int codel_dump(struct Qdisc *sch, struct sk_buff *skb)
{
struct codel_sched_data *q = qdisc_priv(sch);
+ codel_time_t ce_threshold;
struct nlattr *opts;
opts = nla_nest_start_noflag(skb, TCA_OPTIONS);
@@ -190,17 +196,18 @@ static int codel_dump(struct Qdisc *sch, struct sk_buff *skb)
goto nla_put_failure;
if (nla_put_u32(skb, TCA_CODEL_TARGET,
- codel_time_to_us(q->params.target)) ||
+ codel_time_to_us(READ_ONCE(q->params.target))) ||
nla_put_u32(skb, TCA_CODEL_LIMIT,
- sch->limit) ||
+ READ_ONCE(sch->limit)) ||
nla_put_u32(skb, TCA_CODEL_INTERVAL,
- codel_time_to_us(q->params.interval)) ||
+ codel_time_to_us(READ_ONCE(q->params.interval))) ||
nla_put_u32(skb, TCA_CODEL_ECN,
- q->params.ecn))
+ READ_ONCE(q->params.ecn)))
goto nla_put_failure;
- if (q->params.ce_threshold != CODEL_DISABLED_THRESHOLD &&
+ ce_threshold = READ_ONCE(q->params.ce_threshold);
+ if (ce_threshold != CODEL_DISABLED_THRESHOLD &&
nla_put_u32(skb, TCA_CODEL_CE_THRESHOLD,
- codel_time_to_us(q->params.ce_threshold)))
+ codel_time_to_us(ce_threshold)))
goto nla_put_failure;
return nla_nest_end(skb, opts);
--
2.44.0.683.g7961c838ac-goog
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