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Message-ID: <20240415132054.3822230-9-edumazet@google.com>
Date: Mon, 15 Apr 2024 13:20:48 +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 08/14] net_sched: sch_fifo: implement lockless __fifo_dump()
Instead of relying on RTNL, __fifo_dump() can use READ_ONCE()
annotations, paired with WRITE_ONCE() ones in __fifo_init().
Also add missing READ_ONCE(sh->limit) in bfifo_enqueue(),
pfifo_enqueue() and pfifo_tail_enqueue().
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
net/sched/sch_fifo.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/net/sched/sch_fifo.c b/net/sched/sch_fifo.c
index 450f5c67ac4956e21b544dfd81f886714171eced..b50b2c2cc09bc6ee5b23d9d5d3abea4423ff75b9 100644
--- a/net/sched/sch_fifo.c
+++ b/net/sched/sch_fifo.c
@@ -19,7 +19,8 @@
static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
{
- if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <= sch->limit))
+ if (likely(sch->qstats.backlog + qdisc_pkt_len(skb) <=
+ READ_ONCE(sch->limit)))
return qdisc_enqueue_tail(skb, sch);
return qdisc_drop(skb, sch, to_free);
@@ -28,7 +29,7 @@ static int bfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch,
static int pfifo_enqueue(struct sk_buff *skb, struct Qdisc *sch,
struct sk_buff **to_free)
{
- if (likely(sch->q.qlen < sch->limit))
+ if (likely(sch->q.qlen < READ_ONCE(sch->limit)))
return qdisc_enqueue_tail(skb, sch);
return qdisc_drop(skb, sch, to_free);
@@ -39,7 +40,7 @@ static int pfifo_tail_enqueue(struct sk_buff *skb, struct Qdisc *sch,
{
unsigned int prev_backlog;
- if (likely(sch->q.qlen < sch->limit))
+ if (likely(sch->q.qlen < READ_ONCE(sch->limit)))
return qdisc_enqueue_tail(skb, sch);
prev_backlog = sch->qstats.backlog;
@@ -105,14 +106,14 @@ static int __fifo_init(struct Qdisc *sch, struct nlattr *opt,
if (is_bfifo)
limit *= psched_mtu(qdisc_dev(sch));
- sch->limit = limit;
+ WRITE_ONCE(sch->limit, limit);
} else {
struct tc_fifo_qopt *ctl = nla_data(opt);
if (nla_len(opt) < sizeof(*ctl))
return -EINVAL;
- sch->limit = ctl->limit;
+ WRITE_ONCE(sch->limit, ctl->limit);
}
if (is_bfifo)
@@ -154,7 +155,7 @@ static void fifo_destroy(struct Qdisc *sch)
static int __fifo_dump(struct Qdisc *sch, struct sk_buff *skb)
{
- struct tc_fifo_qopt opt = { .limit = sch->limit };
+ struct tc_fifo_qopt opt = { .limit = READ_ONCE(sch->limit) };
if (nla_put(skb, TCA_OPTIONS, sizeof(opt), &opt))
goto nla_put_failure;
--
2.44.0.683.g7961c838ac-goog
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