[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <20220914215357.i7kvrnuczrltdsoj@skbuf>
Date: Wed, 14 Sep 2022 21:53:58 +0000
From: Vladimir Oltean <vladimir.oltean@....com>
To: "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC: Vinicius Costa Gomes <vinicius.gomes@...el.com>,
Jamal Hadi Salim <jhs@...atatu.com>,
Cong Wang <xiyou.wangcong@...il.com>,
Jiri Pirko <jiri@...nulli.us>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Voon Weifeng <weifeng.voon@...el.com>,
Vladimir Oltean <olteanv@...il.com>,
Kurt Kanzenbach <kurt@...utronix.de>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net 3/3] net/sched: taprio: dereference oper and admin
sched under RCU in taprio_destroy
On Wed, Sep 14, 2022 at 05:34:39PM +0300, Vladimir Oltean wrote:
> - if (q->oper_sched)
> - call_rcu(&q->oper_sched->rcu, taprio_free_sched_cb);
> + rcu_read_lock();
> +
> + oper = rcu_dereference(q->oper_sched);
> + admin = rcu_dereference(q->admin_sched);
> +
> + if (oper)
> + call_rcu(&oper->rcu, taprio_free_sched_cb);
>
> - if (q->admin_sched)
> - call_rcu(&q->admin_sched->rcu, taprio_free_sched_cb);
> + if (admin)
> + call_rcu(&admin->rcu, taprio_free_sched_cb);
> +
> + rcu_read_unlock();
> }
I decided to code up this patch at the last minute, since the sparse
warning was bugging me. But after more testing (including with lockdep,
which says absolutely nothing), I notice some RCU stalls after this
patch. It looks like call_rcu() really doesn't like to be called under
rcu_read_lock(). Please discard this patch set from patchwork, I'll
resend when things will work properly.
Powered by blists - more mailing lists