From mboxrd@z Thu Jan  1 00:00:00 1970
From: Johannes Berg <johannes@sipsolutions.net>
Subject: Re: [PATCH] net-tcp: fix panic in tcp_fastopen_cache_set()
Date: Thu, 14 Nov 2013 20:13:38 +0100
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Cc: Dave Jones <davej@redhat.com>, David Miller <davem@davemloft.net>,
	netdev@vger.kernel.org, Yuchung Cheng <ycheng@google.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
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On Wed, 2013-11-13 at 15:00 -0800, Eric Dumazet wrote:

> --- a/net/ipv4/tcp_metrics.c
> +++ b/net/ipv4/tcp_metrics.c
> @@ -663,10 +663,13 @@ void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
>  void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
>  			    struct tcp_fastopen_cookie *cookie, bool syn_lost)
>  {
> +	struct dst_entry *dst = __sk_dst_get(sk);
>  	struct tcp_metrics_block *tm;
>  
> +	if (!dst)
> +		return;
>  	rcu_read_lock();
> -	tm = tcp_get_metrics(sk, __sk_dst_get(sk), true);

Doesn't that __sk_dst_get() have to go inside the rcu_read_lock()?

Then again, I guess we hold the socket. Still looks a bit weird to be
moving it out.

johannes