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Message-ID: <20240415132054.3822230-14-edumazet@google.com>
Date: Mon, 15 Apr 2024 13:20:53 +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 13/14] net_sched: sch_pie: implement lockless pie_dump()
Instead of relying on RTNL, pie_dump() can use READ_ONCE()
annotations, paired with WRITE_ONCE() ones in pie_change().
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
net/sched/sch_pie.c | 39 +++++++++++++++++++++------------------
1 file changed, 21 insertions(+), 18 deletions(-)
diff --git a/net/sched/sch_pie.c b/net/sched/sch_pie.c
index 1764059b063536f619fb4a32b53adfe8c639a8e5..b3dcb845b32759357f4db1980a7cb4db531bfad5 100644
--- a/net/sched/sch_pie.c
+++ b/net/sched/sch_pie.c
@@ -156,36 +156,38 @@ static int pie_change(struct Qdisc *sch, struct nlattr *opt,
u32 target = nla_get_u32(tb[TCA_PIE_TARGET]);
/* convert to pschedtime */
- q->params.target = PSCHED_NS2TICKS((u64)target * NSEC_PER_USEC);
+ WRITE_ONCE(q->params.target,
+ PSCHED_NS2TICKS((u64)target * NSEC_PER_USEC));
}
/* tupdate is in jiffies */
if (tb[TCA_PIE_TUPDATE])
- q->params.tupdate =
- usecs_to_jiffies(nla_get_u32(tb[TCA_PIE_TUPDATE]));
+ WRITE_ONCE(q->params.tupdate,
+ usecs_to_jiffies(nla_get_u32(tb[TCA_PIE_TUPDATE])));
if (tb[TCA_PIE_LIMIT]) {
u32 limit = nla_get_u32(tb[TCA_PIE_LIMIT]);
- q->params.limit = limit;
- sch->limit = limit;
+ WRITE_ONCE(q->params.limit, limit);
+ WRITE_ONCE(sch->limit, limit);
}
if (tb[TCA_PIE_ALPHA])
- q->params.alpha = nla_get_u32(tb[TCA_PIE_ALPHA]);
+ WRITE_ONCE(q->params.alpha, nla_get_u32(tb[TCA_PIE_ALPHA]));
if (tb[TCA_PIE_BETA])
- q->params.beta = nla_get_u32(tb[TCA_PIE_BETA]);
+ WRITE_ONCE(q->params.beta, nla_get_u32(tb[TCA_PIE_BETA]));
if (tb[TCA_PIE_ECN])
- q->params.ecn = nla_get_u32(tb[TCA_PIE_ECN]);
+ WRITE_ONCE(q->params.ecn, nla_get_u32(tb[TCA_PIE_ECN]));
if (tb[TCA_PIE_BYTEMODE])
- q->params.bytemode = nla_get_u32(tb[TCA_PIE_BYTEMODE]);
+ WRITE_ONCE(q->params.bytemode,
+ nla_get_u32(tb[TCA_PIE_BYTEMODE]));
if (tb[TCA_PIE_DQ_RATE_ESTIMATOR])
- q->params.dq_rate_estimator =
- nla_get_u32(tb[TCA_PIE_DQ_RATE_ESTIMATOR]);
+ WRITE_ONCE(q->params.dq_rate_estimator,
+ nla_get_u32(tb[TCA_PIE_DQ_RATE_ESTIMATOR]));
/* Drop excess packets if new limit is lower */
qlen = sch->q.qlen;
@@ -469,17 +471,18 @@ static int pie_dump(struct Qdisc *sch, struct sk_buff *skb)
/* convert target from pschedtime to us */
if (nla_put_u32(skb, TCA_PIE_TARGET,
- ((u32)PSCHED_TICKS2NS(q->params.target)) /
+ ((u32)PSCHED_TICKS2NS(READ_ONCE(q->params.target))) /
NSEC_PER_USEC) ||
- nla_put_u32(skb, TCA_PIE_LIMIT, sch->limit) ||
+ nla_put_u32(skb, TCA_PIE_LIMIT, READ_ONCE(sch->limit)) ||
nla_put_u32(skb, TCA_PIE_TUPDATE,
- jiffies_to_usecs(q->params.tupdate)) ||
- nla_put_u32(skb, TCA_PIE_ALPHA, q->params.alpha) ||
- nla_put_u32(skb, TCA_PIE_BETA, q->params.beta) ||
+ jiffies_to_usecs(READ_ONCE(q->params.tupdate))) ||
+ nla_put_u32(skb, TCA_PIE_ALPHA, READ_ONCE(q->params.alpha)) ||
+ nla_put_u32(skb, TCA_PIE_BETA, READ_ONCE(q->params.beta)) ||
nla_put_u32(skb, TCA_PIE_ECN, q->params.ecn) ||
- nla_put_u32(skb, TCA_PIE_BYTEMODE, q->params.bytemode) ||
+ nla_put_u32(skb, TCA_PIE_BYTEMODE,
+ READ_ONCE(q->params.bytemode)) ||
nla_put_u32(skb, TCA_PIE_DQ_RATE_ESTIMATOR,
- q->params.dq_rate_estimator))
+ READ_ONCE(q->params.dq_rate_estimator)))
goto nla_put_failure;
return nla_nest_end(skb, opts);
--
2.44.0.683.g7961c838ac-goog
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