From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: [PATCH net-next V3] net: dynamic ingress_queue allocation
Date: Mon, 04 Oct 2010 14:52:00 +0200
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Cc: hadi@cyberus.ca, David Miller <davem@davemloft.net>,
	netdev <netdev@vger.kernel.org>
To: Jarek Poplawski <jarkao2@gmail.com>
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Le lundi 04 octobre 2010 =C3=A0 14:06 +0200, Jarek Poplawski a =C3=A9cr=
it :

> Right, but then at least in qdisc_lookup():
>=20
> if (dev_ingress_queue(dev))
> 	q =3D qdisc_match_from_root(dev_ingress_queue(dev), handle);
>=20
> you should use a variable instead of the second dereference (rtnl isn=
't
> mandatory here).

I am lost.

If rntl is not mandatory, what is the lock that protects us ?

qdisc_lookup() _is_ called under the protection of a lock.
Or as soon as we return from it, result could change under us.

Please name it, and I'll use it :

rcu_dereference_protected(dev->ingress_queue, lockdep_is_held(THISLOCK)=
)