In commit b5b73b26b3ca ("taprio: Fix allowing too small intervals"), a
comparison of user input against length_to_duration(q, ETH_ZLEN) was
introduced, to avoid RCU stalls due to frequent hrtimers.
The implementation of length_to_duration() depends on q->picos_per_byte
being set for the link speed. The blamed commit in the Fixes: tag has
moved this too late, so the checks introduced above are ineffective.
The q->picos_per_byte is zero at parse_taprio_schedule() ->
parse_sched_list() -> parse_sched_entry() -> fill_sched_entry() time.
Move the taprio_set_picos_per_byte() call as one of the first things in
taprio_change(), before the bulk of the netlink attribute parsing is
done. That's because it is needed there.
Add a selftest to make sure the issue doesn't get reintroduced.
Fixes: 09dbdf28f9f9 ("net/sched: taprio: fix calculation of maximum gate
durations")
Signed-off-by: Vladimir Oltean <[email protected]>
---
net/sched/sch_taprio.c | 4 +++-
.../tc-testing/tc-tests/qdiscs/taprio.json | 22 +++++++++++++++++++
2 files changed, 25 insertions(+), 1 deletion(-)
diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 1ab17e8a7260..118915055360 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -1848,6 +1848,9 @@ static int taprio_change(struct Qdisc *sch, struct nlattr
*opt,
}
q->flags = taprio_flags;
+ /* Needed for length_to_duration() during netlink attribute parsing */
+ taprio_set_picos_per_byte(dev, q);
+
err = taprio_parse_mqprio_opt(dev, mqprio, extack, q->flags);
if (err < 0)
return err;
@@ -1907,7 +1910,6 @@ static int taprio_change(struct Qdisc *sch, struct nlattr
*opt,
if (err < 0)
goto free_sched;
- taprio_set_picos_per_byte(dev, q);
taprio_update_queue_max_sdu(q, new_admin, stab);
if (FULL_OFFLOAD_IS_ENABLED(q->flags))
diff --git a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
index 12da0a939e3e..8f12f00a4f57 100644
--- a/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
+++ b/tools/testing/selftests/tc-testing/tc-tests/qdiscs/taprio.json
@@ -132,6 +132,28 @@
"echo \"1\" > /sys/bus/netdevsim/del_device"
]
},
+ {
+ "id": "6f62",
+ "name": "Add taprio Qdisc with too short interval",
+ "category": [
+ "qdisc",
+ "taprio"
+ ],
+ "plugins": {
+ "requires": "nsPlugin"
+ },
+ "setup": [
+ "echo \"1 1 8\" > /sys/bus/netdevsim/new_device"
+ ],
+ "cmdUnderTest": "$TC qdisc add dev $ETH root handle 1: taprio num_tc 2
queues 1@0 1@1 sched-entry S 01 300 sched-entry S 02 1700 clockid CLOCK_TAI",
+ "expExitCode": "2",
+ "verifyCmd": "$TC qdisc show dev $ETH",
+ "matchPattern": "qdisc taprio 1: root refcnt",
+ "matchCount": "0",
+ "teardown": [
+ "echo \"1\" > /sys/bus/netdevsim/del_device"
+ ]
+ },
{
"id": "3e1e",
"name": "Add taprio Qdisc with an invalid cycle-time",
--
2.34.1
