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net/sched: taprio: prepare taprio_dump() for RTNL removal

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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>
Link: https://patch.msgid.link/20260501064247.2027688-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2026-05-01 06:42:47 +00:00 committed by Jakub Kicinski
parent 98878ed91b
commit c4994aee02
1 changed files with 24 additions and 18 deletions
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42
net/sched/sch_taprio.c
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@ -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;