Re: BUG: IPv4: Attempt to release TCP socket in state 1

[dormando]

> On Sat, 2013-03-16 at 10:36 -0700, Eric Dumazet wrote:
> > On Fri, 2013-03-15 at 00:19 +0100, Eric Dumazet wrote:
> >
> > > Thanks thats really useful, we might miss to increment socket refcount
> > > in a timer setup.
> > >
> >
> > Hmm, please add following debugging patch as well
> >
> > diff --git a/include/net/sock.h b/include/net/sock.h
> > index 14f6e9d..fe7c8a6 100644
> > --- a/include/net/sock.h
> > +++ b/include/net/sock.h
> > @@ -530,7 +530,9 @@ static inline void sock_hold(struct sock *sk)
> >   */
> >  static inline void __sock_put(struct sock *sk)
> >  {
> > -	atomic_dec(&sk->sk_refcnt);
> > +	int newref = atomic_dec_return(&sk->sk_refcnt);
> > +
> > +	BUG_ON(newref <= 0);
> >  }
> >
> >  static inline bool sk_del_node_init(struct sock *sk)
> > diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
> > index 786d97a..a445e15 100644
> > --- a/net/ipv4/inet_connection_sock.c
> > +++ b/net/ipv4/inet_connection_sock.c
> > @@ -739,7 +739,7 @@ void inet_csk_prepare_forced_close(struct sock *sk)
> >  {
> >  	/* sk_clone_lock locked the socket and set refcnt to 2 */
> >  	bh_unlock_sock(sk);
> > -	sock_put(sk);
> > +	__sock_put(sk);
> >
> >  	/* The below has to be done to allow calling inet_csk_destroy_sock */
> >  	sock_set_flag(sk, SOCK_DEAD);
> > @@ -835,13 +835,13 @@ void inet_csk_listen_stop(struct sock *sk)
> >  			 * tcp_v4_destroy_sock().
> >  			 */
> >  			tcp_sk(child)->fastopen_rsk = NULL;
> > -			sock_put(sk);
> > +			__sock_put(sk);
> >  		}
> >  		inet_csk_destroy_sock(child);
> >
> >  		bh_unlock_sock(child);
> >  		local_bh_enable();
> > -		sock_put(child);
> > +		__sock_put(child);
> >
>
> Please don't include the last line : this should stay as
>
>  sock_put(child);

Hope you don't mind a screenshot:
http://www.dormando.me/p/3.8.2-trace-crash.jpg

(I put the patches on 3.8.2). box is on another continent so screenshot
via IPMI is what I get. If this isn't enough or isn't right I'll try
harder to get the trace logged, I guess?

Thanks!
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