netdev - Re: [PATCH net-next] bridge: remove a redundant synchronize

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Date:	Thu, 4 Apr 2013 18:08:34 +0200
From:	Jiri Pirko <jiri@...nulli.us>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	David Miller <davem@...emloft.net>, vfalico@...hat.com,
	netdev@...r.kernel.org, stephen@...workplumber.org
Subject: Re: [PATCH net-next] bridge: remove a redundant synchronize_net()

Thu, Apr 04, 2013 at 06:03:45PM CEST, eric.dumazet@...il.com wrote:
>On Thu, 2013-04-04 at 08:44 -0700, Eric Dumazet wrote:
>
>> Because maybe the synchronize_net() in netdev_rx_handler_unregister()
>> is enough and you dont even need the call_rcu(). Thats was my question.
>
>So we have the following sequence in team_port_del()
>
>        netdev_rx_handler_unregister(port_dev);
>
>        netdev_upper_dev_unlink(port_dev, dev);
>        team_port_disable_netpoll(port);
>        vlan_vids_del_by_dev(port_dev, dev);
>        dev_uc_unsync(port_dev, dev);
>        dev_mc_unsync(port_dev, dev);
>        dev_close(port_dev);
>        team_port_leave(team, port);
>
>        __team_option_inst_mark_removed_port(team, port);
>        __team_options_change_check(team);
>        __team_option_inst_del_port(team, port);
>        __team_port_change_port_removed(port);
>
>        team_port_set_orig_dev_addr(port);
>        dev_set_mtu(port_dev, port->orig.mtu);
>        synchronize_rcu();
>        kfree(port);
>
>And I suspect we can remove synchronize_rcu() call.

I agree.

>
>But as this is a long list of operations, maybe some of them requires
>the rcu grace period before kfree(port)

None of them requires that.

>
>
>
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