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

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Message-Id: <1459480013.3772171.565370082.48F59FEC@webmail.messagingengine.com>
Date:	Fri, 01 Apr 2016 05:06:53 +0200
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	Eric Dumazet <eric.dumazet@...il.com>,
	Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:	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 Fri, Apr 1, 2016, at 05:03, Eric Dumazet wrote:
> 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.

I certainly can see my mistake now trying to paper over the splats. Do
you object if I send the first patches to fix up the reported lockdep?