netdev - Re: [PATCH net 4/4] tcp: various missing rcu_read_lock around __sk_dst

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Date:	Thu, 31 Mar 2016 20:03:38 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:	Hannes Frederic Sowa <hannes@...essinduktion.org>,
	davem@...emloft.net, netdev@...r.kernel.org,
	sasha.levin@...cle.com, daniel@...earbox.net, mkubecek@...e.cz
Subject: Re: [PATCH net 4/4] tcp: various missing rcu_read_lock around
 __sk_dst_get

On Thu, 2016-03-31 at 18:45 -0700, Alexei Starovoitov wrote:

> Eric, what's your take on Hannes's patch 2 ?
> Is it more accurate to ask lockdep to check for actual lock
> or lockdep can rely on owned flag?
> Potentially there could be races between setting the flag and
> actual lock... but that code is contained, so unlikely.
> Will we find the real issues with this 'stronger' check or
> just spend a ton of time adapting to new model like your other
> patch for release_sock and whatever may need to come next...

More precise lockdep checks are certainly good, I only objected to 4/4
trying to work around another bug.

But why do we rush for 'net' tree ?

This looks net-next material to me.

Locking changes are often subtle, lets take the time to do them
properly.