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Message-ID: <20231009063549.gcehavudj4gxz4oc@soft-dev3-1> Date: Mon, 9 Oct 2023 08:35:49 +0200 From: Horatiu Vultur <horatiu.vultur@...rochip.com> To: Jamal Hadi Salim <jhs@...atatu.com> CC: Chengfeng Ye <dg573847474@...il.com>, Jakub Kicinski <kuba@...nel.org>, <xiyou.wangcong@...il.com>, <jiri@...nulli.us>, <davem@...emloft.net>, <edumazet@...gle.com>, <pabeni@...hat.com>, <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] net/sched: use spin_lock_bh() on &gact->tcf_lock The 10/05/2023 07:46, Jamal Hadi Salim wrote: Hi Jamal, > On Thu, Oct 5, 2023 at 5:01 AM Chengfeng Ye <dg573847474@...il.com> 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@...rochip.com> > Maybe that code needs to run in a tasklet? > In any case your patch is incorrect. I am currently out traveling and it would be a little bit hard for me to look at this right now. I can have a look after I come back in office around mid November. But I was wondering if this is stil an issue for MRP as Cong Wang pointed out, the function __dev_queue_xmit is already disabling the BH. > > cheers, > jamal > -- /Horatiu
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