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net_sched: sch_ets: implement lockless ets_dump()

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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@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 07:32:41 +00:00 committed by David S. Miller
parent a1ac3a7c3d
commit c5f1dde7f7
1 changed files with 14 additions and 11 deletions
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25
net/sched/sch_ets.c
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@ -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;
}