Subject: Re: [PATCH 1/1] net: sctp: dynamically enable or disable pf state

From: Vlad Yasevich <[email-masked]>
Date: Fri, 11 Dec 2015 13:28:18 -0500

On 12/11/2015 04:05 AM, [email-masked] wrote:
> From: Zhu Yanjun <[email-masked]>
> 
> As we all know, the vale of pf_retrans >= max_retrans_path can
> disable pf state. The variables of pf_retrans and max_retrans_path
> can be changed by the user space application.
> 
> Sometimes the user expects to disable pf state while the 2
> variables are changed to enable pf state. So it is necessary to
> introduce a new variable to disable pf state.
> 
> Signed-off-by: Zhu Yanjun <[email-masked]>
> ---
>  Documentation/networking/ip-sysctl.txt |   17 +++++++++++++++++
>  include/net/netns/sctp.h               |    7 +++++++
>  net/sctp/sm_sideeffect.c               |    5 ++++-
>  net/sctp/sysctl.c                      |    9 +++++++++
>  4 files changed, 37 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
> index f647900..7195c24 100644
> --- a/Documentation/networking/ip-sysctl.txt
> +++ b/Documentation/networking/ip-sysctl.txt
> @@ -1723,6 +1723,23 @@ addip_enable - BOOLEAN
>  
>  	Default: 0
>  
> +pf_enable - INTEGER
> +	Enable or disable pf state. A value of pf_retrans > path_max_retrans
> +	also disables pf state. That is, one of both pf_enable and
> +	pf_retrans > path_max_retrans can disable pf state. Since pf_retrans
> +	and path_max_retrans can be changed by userspace application, sometimes
> +	user expects to disable pf state by the value of
> +	pf_retrans > path_max_retrans, but ocassionally the value of pf_retrans
> +	or path_max_retrans is changed by the user application, this pf state is
> +	enabled. As such, it is necessary to add this to dynamically enable
> +	and disable pf state.
> +
> +	1: Enable pf.
> +
> +	0: Disable pf.
> +
> +	Default: 1

You never set the default value anywhere in the patch and thus disable PF extension by
default.

> +
>  addip_noauth_enable - BOOLEAN
>  	Dynamic Address Reconfiguration (ADD-IP) requires the use of
>  	authentication to protect the operations of adding or removing new
> diff --git a/include/net/netns/sctp.h b/include/net/netns/sctp.h
> index 8ba379f..c501d67 100644
> --- a/include/net/netns/sctp.h
> +++ b/include/net/netns/sctp.h
> @@ -89,6 +89,13 @@ struct netns_sctp {
>  	int pf_retrans;
>  
>  	/*
> +	 * Disable Potentially-Failed feature, the feature is enabled by default
> +	 * pf_enable	-  0  : disable pf
> +	 *		- >0  : enable pf
> +	 */
> +	int pf_enable;
> +
> +	/*
>  	 * Policy for preforming sctp/socket accounting
>  	 * 0   - do socket level accounting, all assocs share sk_sndbuf
>  	 * 1   - do sctp accounting, each asoc may use sk_sndbuf bytes
> diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
> index 6098d4c..50309ed 100644
> --- a/net/sctp/sm_sideeffect.c
> +++ b/net/sctp/sm_sideeffect.c
> @@ -477,6 +477,8 @@ static void sctp_do_8_2_transport_strike(sctp_cmd_seq_t *commands,
>  					 struct sctp_transport *transport,
>  					 int is_hb)
>  {
> +	struct net *net = sock_net(asoc->base.sk);
> +
>  	/* The check for association's overall error counter exceeding the
>  	 * threshold is done in the state function.
>  	 */
> @@ -503,7 +505,8 @@ static void sctp_do_8_2_transport_strike(sctp_cmd_seq_t *commands,
>  	 * is SCTP_ACTIVE, then mark this transport as Partially Failed,
>  	 * see SCTP Quick Failover Draft, section 5.1
>  	 */
> -	if ((transport->state == SCTP_ACTIVE) &&
> +	if (net->sctp.pf_enable &&
> +	   (transport->state == SCTP_ACTIVE) &&
>  	   (asoc->pf_retrans < transport->pathmaxrxt) &&
>  	   (transport->error_count > asoc->pf_retrans)) {
>  
> diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c
> index 26d50c5..0a4f402 100644
> --- a/net/sctp/sysctl.c
> +++ b/net/sctp/sysctl.c
> @@ -308,6 +308,15 @@ static struct ctl_table sctp_net_table[] = {
>  		.extra1		= &max_autoclose_min,
>  		.extra2		= &max_autoclose_max,
>  	},
> +	{
> +		.procname	= "pf_enable",
> +		.data		= &init_net.sctp.pf_enable,
> +		.maxlen		= sizeof(int),
> +		.mode		= 0644,
> +		.proc_handler	= proc_dointvec,
> +		.extra1		= &one,
> +		.extra2		= &int_max
> +	},

extra1 and extra2 above are ignored in proc_dointvec.  Don't include them.

-vlad

>  	{ /* sentinel */ }
>  };