On Tue, Nov 14, 2017 at 7:11 PM, Willem de Bruijn <willemdebruijn.ker...@gmail.com> wrote: > On Mon, Nov 13, 2017 at 3:08 PM, John Fastabend > <john.fastab...@gmail.com> wrote: >> sch_direct_xmit() uses qdisc_qlen as a return value but all call sites >> of the routine only check if it is zero or not. Simplify the logic so >> that we don't need to return an actual queue length value. >> >> This introduces a case now where sch_direct_xmit would have returned >> a qlen of zero but now it returns true. > > You mean the first case, when the likely(skb) branch failed? > Can that return false, then?
I misunderstood. __qdisc_run will just take one extra loop, since it will no longer break out of the loop on reading the last packet on the queue with qdisc_restart. That does have a subtle (but benign if rare) side effect of possibly calling __netif_schedule while there is nothing queued, if either the quota is exactly exhausted or need_resched is true.
