From: Kuniyuki Iwashima <kuniyu@amazon.com>
To: <sdf@fomichev.me>
Cc: <andrew+netdev@lunn.ch>, <atenart@kernel.org>,
<davem@davemloft.net>, <edumazet@google.com>, <enjuk@amazon.com>,
<horms@kernel.org>, <jasowang@redhat.com>, <jdamato@fastly.com>,
<kory.maincent@bootlin.com>, <kuba@kernel.org>,
<kuniyu@amazon.com>, <linux-kernel@vger.kernel.org>,
<netdev@vger.kernel.org>, <pabeni@redhat.com>,
<willemdebruijn.kernel@gmail.com>
Subject: Re: [PATCH net-next v2 2/2] net: reorder dev_addr_sem lock
Date: Thu, 13 Mar 2025 10:56:00 -0700 [thread overview]
Message-ID: <20250313175603.17045-1-kuniyu@amazon.com> (raw)
In-Reply-To: <20250312190513.1252045-3-sdf@fomichev.me>
From: Stanislav Fomichev <sdf@fomichev.me>
Date: Wed, 12 Mar 2025 12:05:13 -0700
> Lockdep complains about circular lock in 1 -> 2 -> 3 (see below).
>
> Change the lock ordering to be:
> - rtnl_lock
> - dev_addr_sem
> - netdev_ops (only for lower devices!)
> - team_lock (or other per-upper device lock)
>
> 1. rtnl_lock -> netdev_ops -> dev_addr_sem
>
> rtnl_setlink
> rtnl_lock
> do_setlink IFLA_ADDRESS on lower
> netdev_ops
> dev_addr_sem
>
> 2. rtnl_lock -> team_lock -> netdev_ops
>
> rtnl_newlink
> rtnl_lock
> do_setlink IFLA_MASTER on lower
> do_set_master
> team_add_slave
> team_lock
> team_port_add
> dev_set_mtu
> netdev_ops
>
> 3. rtnl_lock -> dev_addr_sem -> team_lock
>
> rtnl_newlink
> rtnl_lock
> do_setlink IFLA_ADDRESS on upper
> dev_addr_sem
> netif_set_mac_address
> team_set_mac_address
> team_lock
>
> 4. rtnl_lock -> netdev_ops -> dev_addr_sem
>
> rtnl_lock
> dev_ifsioc
> dev_set_mac_address_user
>
> __tun_chr_ioctl
> rtnl_lock
> dev_set_mac_address_user
>
> tap_ioctl
> rtnl_lock
> dev_set_mac_address_user
>
> dev_set_mac_address_user
> netdev_lock_ops
> netif_set_mac_address_user
> dev_addr_sem
>
> v2:
> - move lock reorder to happen after kmalloc (Kuniyuki)
My intention was move kmalloc() and memcpy() out of both
netdev_lock and dev_addr_sem like
netdev_ops_unlock()
kmalloc()
memcpy()
down_write()
, but not a big deal :)
>
> Cc: Kohei Enju <enjuk@amazon.com>
> Fixes: df43d8bf1031 ("net: replace dev_addr_sem with netdev instance lock")
> Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
next prev parent reply other threads:[~2025-03-13 17:56 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-03-12 19:05 [PATCH net-next v2 0/2] net: bring back dev_addr_sem Stanislav Fomichev
2025-03-12 19:05 ` [PATCH net-next v2 1/2] Revert "net: replace dev_addr_sem with netdev instance lock" Stanislav Fomichev
2025-03-12 19:05 ` [PATCH net-next v2 2/2] net: reorder dev_addr_sem lock Stanislav Fomichev
2025-03-13 17:56 ` Kuniyuki Iwashima [this message]
2025-03-17 8:15 ` [PATCH net-next v2 0/2] net: bring back dev_addr_sem Lei Yang
2025-03-19 18:00 ` patchwork-bot+netdevbpf
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