netdev - Re: [PATCH net] tun, bpf: fix suspicious RCU usage in tun_{attach,detach}

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Message-ID: <56FD1512.70409@iogearbox.net>
Date:	Thu, 31 Mar 2016 14:16:18 +0200
From:	Daniel Borkmann <daniel@...earbox.net>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	Alexei Starovoitov <alexei.starovoitov@...il.com>,
	Michal Kubecek <mkubecek@...e.cz>, davem@...emloft.net,
	sasha.levin@...cle.com, jslaby@...e.cz, mst@...hat.com,
	netdev@...r.kernel.org
Subject: Re: [PATCH net] tun, bpf: fix suspicious RCU usage in tun_{attach,detach}_filter

On 03/31/2016 01:59 PM, Eric Dumazet wrote:
> On Thu, 2016-03-31 at 13:35 +0200, Daniel Borkmann wrote:
>
>> +static inline bool sock_owned_externally(const struct sock *sk)
>> +{
>> +	return sk->sk_flags & (1UL << SOCK_EXTERNAL_OWNER);
>> +}
>> +
>
> Have you reinvented sock_flag(sl, SOCK_EXTERNAL_OWNER) ? ;)
>
> Anyway, using a flag for this purpose sounds overkill to me.

Right.

> Setting it is a way to 'fool' lockdep anyway...

Yep, correct, we'd be fooling the tun case, so this diff doesn't
really make it any better there.

Thanks,
Daniel