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charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Thu, Aug 15, 2024 at 01:23:05AM +0000, Jianbo Liu wrote: > On Wed, 2024-08-14 at 11:11 +0800, Hangbin Liu wrote: > > On Wed, Aug 14, 2024 at 02:03:58AM +0000, Jianbo Liu wrote: > > > On Tue, 2024-08-13 at 07:14 -0700, Jakub Kicinski wrote: > > > > On Tue, 13 Aug 2024 02:58:12 +0000 Jianbo Liu wrote: > > > > > > > +       rcu_read_lock(); > > > > > > > +       bond = netdev_priv(bond_dev); > > > > > > > +       slave = rcu_dereference(bond->curr_active_slave); > > > > > > > +       real_dev = slave ? slave->dev : NULL; > > > > > > > +       rcu_read_unlock();  > > > > > > > > > > > > What's holding onto real_dev once you drop the rcu lock > > > > > > here?  > > > > > > > > > > I think it should be xfrm state (and bond device). > > > > > > > > Please explain it in the commit message in more certain terms. > > > > > > Sorry, I don't understand. The real_dev is saved in xs- > > > >xso.real_dev, > > > and also bond's slave. It's straightforward. What else do I need to > > > explain? > > > > I think Jakub means you need to make sure the real_dev is not freed > > during > > xfrmdev_ops. See bond_ipsec_add_sa(). You unlock it too early and > > later > > xfrmdev_ops is not protected. > > This RCU lock is to protect the reading of curr_active_slave, which is > pointing to a big stuct - slave struct, so there is no error to get > real_dev from slave->dev. It's not about getting real_dev from slave->dev. As Jakub said, What's holding on real_dev once you drop the rcu lock? Thanks Hangbin