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net_sched: sch_pie: implement lockless pie_dump()

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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@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2024-04-18 07:32:47 +00:00 committed by David S. Miller
parent 293c7e2b3e
commit 6c00dc4fdb
1 changed files with 21 additions and 18 deletions
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39
net/sched/sch_pie.c
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@ -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);