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Message-ID: <20240415132054.3822230-8-edumazet@google.com>
Date: Mon, 15 Apr 2024 13:20:47 +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 07/14] net_sched: sch_ets: implement lockless ets_dump()
Instead of relying on RTNL, ets_dump() can use READ_ONCE()
annotations, paired with WRITE_ONCE() ones in ets_change().
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
net/sched/sch_ets.c | 25 ++++++++++++++-----------
1 file changed, 14 insertions(+), 11 deletions(-)
diff --git a/net/sched/sch_ets.c b/net/sched/sch_ets.c
index 835b4460b44854a803d3054e744702022b7551f4..f80bc05d4c5a5050226e6cfd30fa951c0b61029f 100644
--- a/net/sched/sch_ets.c
+++ b/net/sched/sch_ets.c
@@ -646,7 +646,7 @@ static int ets_qdisc_change(struct Qdisc *sch, struct nlattr *opt,
sch_tree_lock(sch);
- q->nbands = nbands;
+ WRITE_ONCE(q->nbands, nbands);
for (i = nstrict; i < q->nstrict; i++) {
if (q->classes[i].qdisc->q.qlen) {
list_add_tail(&q->classes[i].alist, &q->active);
@@ -658,11 +658,11 @@ static int ets_qdisc_change(struct Qdisc *sch, struct nlattr *opt,
list_del(&q->classes[i].alist);
qdisc_tree_flush_backlog(q->classes[i].qdisc);
}
- q->nstrict = nstrict;
+ WRITE_ONCE(q->nstrict, nstrict);
memcpy(q->prio2band, priomap, sizeof(priomap));
for (i = 0; i < q->nbands; i++)
- q->classes[i].quantum = quanta[i];
+ WRITE_ONCE(q->classes[i].quantum, quanta[i]);
for (i = oldbands; i < q->nbands; i++) {
q->classes[i].qdisc = queues[i];
@@ -676,7 +676,7 @@ static int ets_qdisc_change(struct Qdisc *sch, struct nlattr *opt,
for (i = q->nbands; i < oldbands; i++) {
qdisc_put(q->classes[i].qdisc);
q->classes[i].qdisc = NULL;
- q->classes[i].quantum = 0;
+ WRITE_ONCE(q->classes[i].quantum, 0);
q->classes[i].deficit = 0;
gnet_stats_basic_sync_init(&q->classes[i].bstats);
memset(&q->classes[i].qstats, 0, sizeof(q->classes[i].qstats));
@@ -733,6 +733,7 @@ static int ets_qdisc_dump(struct Qdisc *sch, struct sk_buff *skb)
struct ets_sched *q = qdisc_priv(sch);
struct nlattr *opts;
struct nlattr *nest;
+ u8 nbands, nstrict;
int band;
int prio;
int err;
@@ -745,21 +746,22 @@ static int ets_qdisc_dump(struct Qdisc *sch, struct sk_buff *skb)
if (!opts)
goto nla_err;
- if (nla_put_u8(skb, TCA_ETS_NBANDS, q->nbands))
+ nbands = READ_ONCE(q->nbands);
+ if (nla_put_u8(skb, TCA_ETS_NBANDS, nbands))
goto nla_err;
- if (q->nstrict &&
- nla_put_u8(skb, TCA_ETS_NSTRICT, q->nstrict))
+ nstrict = READ_ONCE(q->nstrict);
+ if (nstrict && nla_put_u8(skb, TCA_ETS_NSTRICT, nstrict))
goto nla_err;
- if (q->nbands > q->nstrict) {
+ if (nbands > nstrict) {
nest = nla_nest_start(skb, TCA_ETS_QUANTA);
if (!nest)
goto nla_err;
- for (band = q->nstrict; band < q->nbands; band++) {
+ for (band = nstrict; band < nbands; band++) {
if (nla_put_u32(skb, TCA_ETS_QUANTA_BAND,
- q->classes[band].quantum))
+ READ_ONCE(q->classes[band].quantum)))
goto nla_err;
}
@@ -771,7 +773,8 @@ static int ets_qdisc_dump(struct Qdisc *sch, struct sk_buff *skb)
goto nla_err;
for (prio = 0; prio <= TC_PRIO_MAX; prio++) {
- if (nla_put_u8(skb, TCA_ETS_PRIOMAP_BAND, q->prio2band[prio]))
+ if (nla_put_u8(skb, TCA_ETS_PRIOMAP_BAND,
+ READ_ONCE(q->prio2band[prio])))
goto nla_err;
}
--
2.44.0.683.g7961c838ac-goog
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