Re: [PATCH net] net: lapbether: Prevent racing when checking whether the netif is running

From: Xie He
Date: Thu Mar 11 2021 - 19:29:55 EST


On Thu, Mar 11, 2021 at 4:10 PM Jakub Kicinski <kuba@xxxxxxxxxx> wrote:
>
> And the "noqueue" queue is there because it's on top of hdlc_fr.c
> somehow or some out of tree driver? Or do you install it manually?

No, this driver is not related to "hdlc_fr.c" or any out-of-tree
driver. The default qdisc is "noqueue" for this driver because this
driver doesn't set "tx_queue_len". This means the value of
"tx_queue_len" would be 0. In this case, "alloc_netdev_mqs" will
automatically add the "IFF_NO_QUEUE" flag to the device, then
"attach_one_default_qdisc" in "net/sched/sch_generic.c" will attach
the "noqueue" qdisc for devices with the "IFF_NO_QUEUE" flag.