Re: [PATCH] net/sched: use spin_lock_bh() on &gact->tcf_lock

[Jamal Hadi Salim]

On Thu, Oct 5, 2023 at 5:01 AM Chengfeng Ye <dg573847474@xxxxxxxxx> wrote:
>
> Hi Jakub,
>
> Thanks for the reply,
>
> I inspected the code a bit more, it seems that the TC action is called from
> tcf_proto_ops.classify() callback, which is called from Qdisc_ops enqueue
> callback.
>
> Then Qdisc enqueue callback is from
>
> -> __dev_queue_xmit()
> -> __dev_xmit_skb()
> -> dev_qdisc_enqueue()
>
> inside the net core. It seems that this __dev_queue_xmit() callback is
> typically called from BH context (e.g.,  NET_TX_SOFTIRQ) with BH
> already disabled, but sometimes also can from a work queue under
> process context, one case is the br_mrp_test_work_expired() inside
> net/bridge/br_mrp.c. Does it indicate that this TC action could also be
> called with BH enable? I am not a developer so really not sure about it,
> as the networking code is a bit long and complicated.

net/bridge/br_mrp.c seems to need some love +Cc Horatiu Vultur
<horatiu.vultur@xxxxxxxxxxxxx>
Maybe that code needs to run in a tasklet?
In any case your patch is incorrect.

cheers,
jamal