On Mon, May 27, 2024 at 5:40 PM Vladimir Oltean vladimir.oltean@nxp.com wrote:
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 vladimir.oltean@nxp.com
Reviewed-by: Eric Dumazet edumazet@google.com
Thanks!