Re: [PATCH net v2 1/3] net/sched: taprio: catch up in bounded time when the schedule falls behind

On Mon, 24 Aug 2026 11:53:35 -0700, Jakub Kicinski [off-list ref] wrote:

No Link: tags present in the commit header.

v3 will carry the syzbot tags, including a fourth bucket akpm had syzbot
test this patch alone against:
https://lore.kernel.org/all/6a936ec2.4d659fcc.734b4.0032.GAE@google.com/ (local)

has a second exit condition (--budget), so taprio_catch_up() can return

[...]

jump makes end == now, and the strict ktime_before(end, now) test then skips

Right. v3 treats end == now as behind, in the walk and its caller, and
the comment mentions the cap.

case, so a large gate control list turns a previously O(1) critical section
into an O(num_entries) walk over separately allocated entries.

One lap at most per hold now, versus no bound at all before. Leaving it
as is.

inoperative. Adding N * cycle_time then shifts the timeline by
(N * cycle_time) modulo the interval sum, and the gate_close_time[] values

Yes. v3 jumps whole laps instead: min(cycle_time, sum of intervals) on
the entry timeline, cycle_time on cycle_end_time, i.e. exactly what N
restarts of the current code do.

then terminates on budget exhaustion with end < now, and behind stays below

[...]

changelog describes does not converge at all. Is the intent that this patch
depends on the minimum interval patch for the bound to hold?

No. With the jump in laps the residual is under one lap, so the walk
finishes within num_entries steps for any schedule. v3 drops 2/3 anyway.

be observed torn, which is also pre-existing. Is it worth a comment that
advance_sched() may legitimately update the currently published entry?

Yes, will add.