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net_sched: sch_codel: implement lockless codel_dump()

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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@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 07:32:39 +00:00 committed by David S. Miller
parent 7253c1d1e7
commit c45bd26c82
1 changed files with 18 additions and 11 deletions
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29
net/sched/sch_codel.c
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@ -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);