From: Eric Dumazet <edumazet@google.com>
To: "David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>
Cc: Simon Horman <horms@kernel.org>,
Jamal Hadi Salim <jhs@mojatatu.com>,
Jiri Pirko <jiri@resnulli.us>,
netdev@vger.kernel.org, eric.dumazet@gmail.com,
Eric Dumazet <edumazet@google.com>
Subject: [PATCH net-next] net/sched: taprio: prepare taprio_dump() for RTNL removal
Date: Fri, 1 May 2026 06:42:47 +0000 [thread overview]
Message-ID: <20260501064247.2027688-1-edumazet@google.com> (raw)
We soon will no longer hold RTNL in qdisc dumps.
Add READ_ONCE()/WRITE_ONCE() annotations.
Note: taprio already uses RCU to protect most of its fields.
Signed-off-by: Eric Dumazet <edumazet@google.com>
---
net/sched/sch_taprio.c | 42 ++++++++++++++++++++++++------------------
1 file changed, 24 insertions(+), 18 deletions(-)
diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 45245157e00a69311304f8c69f9ee9d80bc4f4d8..71b690e1974dad8fbab7e12998e03f86a0847a98 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -308,10 +308,10 @@ static void taprio_update_queue_max_sdu(struct taprio_sched *q,
if (max_sdu != U32_MAX) {
sched->max_frm_len[tc] = max_sdu + dev->hard_header_len;
- sched->max_sdu[tc] = max_sdu;
+ WRITE_ONCE(sched->max_sdu[tc], max_sdu);
} else {
sched->max_frm_len[tc] = U32_MAX; /* never oversized */
- sched->max_sdu[tc] = 0;
+ WRITE_ONCE(sched->max_sdu[tc], 0);
}
}
}
@@ -1771,8 +1771,8 @@ static int taprio_parse_tc_entries(struct Qdisc *sch,
}
for (tc = 0; tc < TC_QOPT_MAX_QUEUE; tc++) {
- q->max_sdu[tc] = max_sdu[tc];
- q->fp[tc] = fp[tc];
+ WRITE_ONCE(q->max_sdu[tc], max_sdu[tc]);
+ WRITE_ONCE(q->fp[tc], fp[tc]);
if (fp[tc] != TC_FP_EXPRESS)
have_preemption = true;
}
@@ -1852,12 +1852,14 @@ static int taprio_change(struct Qdisc *sch, struct nlattr *opt,
return -EINVAL;
}
- if (q->flags != TAPRIO_FLAGS_INVALID && q->flags != taprio_flags) {
- NL_SET_ERR_MSG_MOD(extack,
- "Changing 'flags' of a running schedule is not supported");
- return -EOPNOTSUPP;
+ if (q->flags != taprio_flags) {
+ if (q->flags != TAPRIO_FLAGS_INVALID) {
+ NL_SET_ERR_MSG_MOD(extack,
+ "Changing 'flags' of a running schedule is not supported");
+ return -EOPNOTSUPP;
+ }
+ WRITE_ONCE(q->flags, taprio_flags);
}
- q->flags = taprio_flags;
/* Needed for length_to_duration() during netlink attribute parsing */
taprio_set_picos_per_byte(dev, q, extack);
@@ -1940,7 +1942,8 @@ static int taprio_change(struct Qdisc *sch, struct nlattr *opt,
goto unlock;
}
- q->txtime_delay = nla_get_u32(tb[TCA_TAPRIO_ATTR_TXTIME_DELAY]);
+ WRITE_ONCE(q->txtime_delay,
+ nla_get_u32(tb[TCA_TAPRIO_ATTR_TXTIME_DELAY]));
}
if (!TXTIME_ASSIST_IS_ENABLED(q->flags) &&
@@ -2283,8 +2286,8 @@ static int dump_schedule(struct sk_buff *msg,
}
static int taprio_dump_tc_entries(struct sk_buff *skb,
- struct taprio_sched *q,
- struct sched_gate_list *sched)
+ const struct taprio_sched *q,
+ const struct sched_gate_list *sched)
{
struct nlattr *n;
int tc;
@@ -2298,10 +2301,11 @@ static int taprio_dump_tc_entries(struct sk_buff *skb,
goto nla_put_failure;
if (nla_put_u32(skb, TCA_TAPRIO_TC_ENTRY_MAX_SDU,
- sched->max_sdu[tc]))
+ READ_ONCE(sched->max_sdu[tc])))
goto nla_put_failure;
- if (nla_put_u32(skb, TCA_TAPRIO_TC_ENTRY_FP, q->fp[tc]))
+ if (nla_put_u32(skb, TCA_TAPRIO_TC_ENTRY_FP,
+ READ_ONCE(q->fp[tc])))
goto nla_put_failure;
nla_nest_end(skb, n);
@@ -2387,6 +2391,7 @@ static int taprio_dump(struct Qdisc *sch, struct sk_buff *skb)
struct sched_gate_list *oper, *admin;
struct tc_mqprio_qopt opt = { 0 };
struct nlattr *nest, *sched_nest;
+ u32 txtime_delay;
mqprio_qopt_reconstruct(dev, &opt);
@@ -2404,14 +2409,15 @@ static int taprio_dump(struct Qdisc *sch, struct sk_buff *skb)
if (q->flags && nla_put_u32(skb, TCA_TAPRIO_ATTR_FLAGS, q->flags))
goto options_error;
- if (q->txtime_delay &&
- nla_put_u32(skb, TCA_TAPRIO_ATTR_TXTIME_DELAY, q->txtime_delay))
+ txtime_delay = READ_ONCE(q->txtime_delay);
+ if (txtime_delay &&
+ nla_put_u32(skb, TCA_TAPRIO_ATTR_TXTIME_DELAY, txtime_delay))
goto options_error;
rcu_read_lock();
- oper = rtnl_dereference(q->oper_sched);
- admin = rtnl_dereference(q->admin_sched);
+ oper = rcu_dereference(q->oper_sched);
+ admin = rcu_dereference(q->admin_sched);
if (oper && taprio_dump_tc_entries(skb, q, oper))
goto options_error_rcu;
--
2.54.0.545.g6539524ca2-goog
next reply other threads:[~2026-05-01 6:42 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-01 6:42 Eric Dumazet [this message]
2026-05-02 17:22 ` [PATCH net-next] net/sched: taprio: prepare taprio_dump() for RTNL removal Eric Dumazet
2026-05-05 2:00 ` patchwork-bot+netdevbpf
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