From: Ivan Vecera <ivecera@redhat.com>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Linux Kernel Network Developers <netdev@vger.kernel.org>,
Jiri Pirko <jiri@resnulli.us>,
"David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Saeed Mahameed <saeed@kernel.org>
Subject: Re: [PATCH net] team: protect features update by RCU to avoid deadlock
Date: Tue, 26 Jan 2021 07:36:12 +0100 [thread overview]
Message-ID: <20210126073612.05e8c302@ceranb> (raw)
In-Reply-To: <CAM_iQpX85wZn0ihG_XxPq=inM5P8dKvf4BE6kNwG2na=NAnGzw@mail.gmail.com>
On Mon, 25 Jan 2021 12:53:22 -0800
Cong Wang <xiyou.wangcong@gmail.com> wrote:
> On Sun, Jan 24, 2021 at 11:44 PM Ivan Vecera <ivecera@redhat.com> wrote:
> >
> > Function __team_compute_features() is protected by team->lock
> > mutex when it is called from team_compute_features() used when
> > features of an underlying device is changed. This causes
> > a deadlock when NETDEV_FEAT_CHANGE notifier for underlying device
> > is fired due to change propagated from team driver (e.g. MTU
> > change). It's because callbacks like team_change_mtu() or
> > team_vlan_rx_{add,del}_vid() protect their port list traversal
> > by team->lock mutex.
> >
> > Example (r8169 case where this driver disables TSO for certain MTU
> > values):
> > ...
> > [ 6391.348202] __mutex_lock.isra.6+0x2d0/0x4a0
> > [ 6391.358602] team_device_event+0x9d/0x160 [team]
> > [ 6391.363756] notifier_call_chain+0x47/0x70
> > [ 6391.368329] netdev_update_features+0x56/0x60
> > [ 6391.373207] rtl8169_change_mtu+0x14/0x50 [r8169]
> > [ 6391.378457] dev_set_mtu_ext+0xe1/0x1d0
> > [ 6391.387022] dev_set_mtu+0x52/0x90
> > [ 6391.390820] team_change_mtu+0x64/0xf0 [team]
> > [ 6391.395683] dev_set_mtu_ext+0xe1/0x1d0
> > [ 6391.399963] do_setlink+0x231/0xf50
> > ...
> >
> > In fact team_compute_features() called from team_device_event()
> > does not need to be protected by team->lock mutex and rcu_read_lock()
> > is sufficient there for port list traversal.
>
> Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
>
> In the future, please version your patch so that we can easily
> find out which is the latest.
OK, got it... I haven't added a version due to different subjects...
Thanks,
Ivan
next prev parent reply other threads:[~2021-01-26 17:03 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-25 7:44 [PATCH net] team: protect features update by RCU to avoid deadlock Ivan Vecera
2021-01-25 20:53 ` Cong Wang
2021-01-26 6:36 ` Ivan Vecera [this message]
2021-01-26 10:02 ` Jiri Pirko
2021-01-27 1:20 ` patchwork-bot+netdevbpf
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