Re: [PATCH net-next] tcp: fix lockdep splat in tcp_snd_una_update()

[David Miller <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>]

From: Eric Dumazet <eric.dumazet-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Date: Tue, 03 May 2016 16:56:03 -0700

> From: Eric Dumazet <edumazet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> 
> tcp_snd_una_update() and tcp_rcv_nxt_update() call
> u64_stats_update_begin() either from process context or BH handler.
> 
> This triggers a lockdep splat on 32bit & SMP builds.
> 
> We could add u64_stats_update_begin_bh() variant but this would
> slow down 32bit builds with useless local_disable_bh() and
> local_enable_bh() pairs, since we own the socket lock at this point.
> 
> I add sock_owned_by_me() helper to have proper lockdep support
> even on 64bit builds, and new u64_stats_update_begin_raw()
> and u64_stats_update_end_raw methods.
> 
> Fixes: c10d9310edf5 ("tcp: do not assume TCP code is non preemptible")
> Reported-by: Fabio Estevam <festevam-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> Diagnosed-by: Francois Romieu <romieu-W8zweXLXuWQS+FvcfC7Uqw@public.gmane.org>
> Signed-off-by: Eric Dumazet <edumazet-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>

Applied.
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