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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 5 Oct 2023 17:01:07 +0800
From:   Chengfeng Ye <dg573847474@...il.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     jhs@...atatu.com, 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

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.

Thanks again,
Chengfeng