netdev - Re: [PATCH net,v2] tcp: Fix broken repair socket window probe patch

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Date:   Mon, 16 Jul 2018 10:51:50 -0700
From:   Andrey Vagin <avagin@...tuozzo.com>
To:     Stefan Baranoff <sbaranoff@...il.com>
Cc:     Pavel Emelyanov <xemul@...tuozzo.com>,
        Eric Dumazet <edumazet@...gle.com>,
        "David S. Miller" <davem@...emloft.net>,
        Alexey Kuznetsov <kuznet@....inr.ac.ru>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net,v2] tcp: Fix broken repair socket window probe patch

On Sun, Jul 15, 2018 at 11:36:37AM -0400, Stefan Baranoff wrote:
> Correct previous bad attempt at allowing sockets to come out of TCP
> repair without sending window probes. To avoid changing size of
> the repair variable in struct tcp_sock, this lets the decision for
> sending probes or not to be made when coming out of repair by
> introducing two ways to turn it off.
> 
> v2:
> * Remove erroneous comment; defines now make behavior clear
> 
> Fixes: 70b7ff130224 ("tcp: allow user to create repair socket without window probes")
> Signed-off-by: Stefan Baranoff <sbaranoff@...il.com>

Acked-by: Andrei Vagin <avagin@...tuozzo.com>

> ---
>  include/uapi/linux/tcp.h |  4 ++++
>  net/ipv4/tcp.c           | 13 +++++++------
>  2 files changed, 11 insertions(+), 6 deletions(-)
> 
> diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
> index 29eb659..e3f6ed8 100644
> --- a/include/uapi/linux/tcp.h
> +++ b/include/uapi/linux/tcp.h
> @@ -127,6 +127,10 @@ enum {
>  
>  #define TCP_CM_INQ		TCP_INQ
>  
> +#define TCP_REPAIR_ON		1
> +#define TCP_REPAIR_OFF		0
> +#define TCP_REPAIR_OFF_NO_WP	-1	/* Turn off without window probes */
> +
>  struct tcp_repair_opt {
>  	__u32	opt_code;
>  	__u32	opt_val;
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index 8e5e2ca..ec2186e 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -2823,16 +2823,17 @@ static int do_tcp_setsockopt(struct sock *sk, int level,
>  	case TCP_REPAIR:
>  		if (!tcp_can_repair_sock(sk))
>  			err = -EPERM;
> -		/* 1 for normal repair, 2 for no window probes */
> -		else if (val == 1 || val == 2) {
> -			tp->repair = val;
> +		else if (val == TCP_REPAIR_ON) {
> +			tp->repair = 1;
>  			sk->sk_reuse = SK_FORCE_REUSE;
>  			tp->repair_queue = TCP_NO_QUEUE;
> -		} else if (val == 0) {
> +		} else if (val == TCP_REPAIR_OFF) {
> +			tp->repair = 0;
> +			sk->sk_reuse = SK_NO_REUSE;
> +			tcp_send_window_probe(sk);
> +		} else if (val == TCP_REPAIR_OFF_NO_WP) {
>  			tp->repair = 0;
>  			sk->sk_reuse = SK_NO_REUSE;
> -			if (tp->repair == 1)
> -				tcp_send_window_probe(sk);
>  		} else
>  			err = -EINVAL;
>  
> -- 
> 1.8.3.1
>