[CRIU] [PATCH] tcp: refresh a data about tcp connection after blocking it (v2)

[Andrew Vagin]

On Thu, Nov 15, 2012 at 06:08:05PM +0400, Pavel Emelyanov wrote:
> On 11/15/2012 04:14 PM, Andrey Vagin wrote:
> > We have a window between getting info about tcp connections
> > and blocking them. States of tcp connections can be changes,
> > so they should be refreshed after blocking.
> > 
> > https://bugzilla.openvz.org/show_bug.cgi?id=2419
> > 
> > v2: clean up
> > 
> > Signed-off-by: Andrey Vagin <avagin at openvz.org>
> > ---
> >  sk-tcp.c | 42 ++++++++++++++++++++++++++++++++++++++++++
> >  1 file changed, 42 insertions(+)
> > 
> > diff --git a/sk-tcp.c b/sk-tcp.c
> > index 9e01a08..99c8de2 100644
> > --- a/sk-tcp.c
> > +++ b/sk-tcp.c
> > @@ -51,6 +51,43 @@ static int tcp_repair_on(int fd)
> >  	return ret;
> >  }
> >  
> > +static int refresh_inet_sk(int fd, struct inet_sk_desc *sk)
> > +{
> > +	int size;
> > +	struct tcp_info info;
> > +
> > +	if (sk->state == TCP_CLOSE)
> > +		return 0;
> > +
> > +	if (dump_opt(fd, SOL_TCP, TCP_INFO, &info)) {
> > +		pr_perror("Failt to obtain TCP_INFO");
> > +		return -1;
> > +	}
> > +
> > +	sk->state = info.tcpi_state;
> > +
> > +	if (sk->state == TCP_LISTEN) {
> > +		sk->rqlen = info.tcpi_unacked;
> > +		sk->wqlen = info.tcpi_sacked;
> 
> What is this for?

I didn't know that this fields are not used for TCP_LISTEN.

> 
> > +	} else {
> > +		if (ioctl(fd, SIOCOUTQ, &size) == -1) {
> > +			pr_perror("Unable to get size of snd queue");
> > +			return -1;
> > +		}
> > +
> > +		sk->wqlen = size;
> > +
> > +		if (ioctl(fd, SIOCINQ, &size) == -1) {
> > +			pr_perror("Unable to get size of recv queue");
> > +			return -1;
> > +		}
> > +
> > +		sk->rqlen = size;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> >  static int tcp_repair_establised(int fd, struct inet_sk_desc *sk)
> >  {
> >  	int ret;
> > @@ -71,6 +108,11 @@ static int tcp_repair_establised(int fd, struct inet_sk_desc *sk)
> >  		ret = nf_lock_connection(sk);
> >  		if (ret < 0)
> >  			goto err2;
> > +
> > +		/* A state of a tcp connection could be changed */
> > +		ret = refresh_inet_sk(sk->rfd, sk);
> > +		if (ret < 0)
> > +			goto err2;
> >  	}
> >  
> >  	ret = tcp_repair_on(sk->rfd);
> > 
> 
>