Messages in this thread | | | Subject | Re: [PATCH] rtnetlink: Synchronze net in rtnl_unregister() | From | Dmitry Safonov <> | Date | Mon, 25 Feb 2019 23:27:42 +0000 |
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On 2/25/19 11:21 PM, Dmitry Safonov wrote: > Hi Eric, > > On 2/25/19 11:09 PM, Eric Dumazet wrote: >> On 02/25/2019 01:27 PM, Dmitry Safonov wrote: >>> While it's possible to document that rtnl_unregister() requires >>> synchronize_net() afterwards - unlike rtnl_unregister_all(), I believe >>> the module exit is very much slow-path. >> >> rtnl_unregister_all() needs the sychronize_rcu() at this moment >> because of the kfree(tab), not because of the kfree_rcu(link, rcu); > > I may be wrong here, but shouldn't we wait for grace period to elapse by > the reason that rtnl_msg_handlers are protected by RCU, not only by rtnl? > Like, without synchronize_net() in rtnl_unregister() - what prevents > module exit race to say, rtnetlink_rcv_msg()=>rtnl_get_link()?
There is synchronize_rcu() in free_module() - but I believe it's a bit too far in unloading. Maybe, I'm missing another call on the way.
Thanks, Dmitry
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