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

[Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>]

On Wed, Dec 16, 2015 at 01:55:04PM +0800, zyjzyj2000@gmail.com wrote:
> From: Zhu Yanjun <zyjzyj2000@gmail.com>
> 
> As we all know, the value of pf_retrans >= max_retrans_path can
> disable pf state. The variables of pf_retrans and max_retrans_path
> can be changed by the userspace 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.
> 
> According to the suggestions from Vlad Yasevich, extra1 and extra2
> are removed. The initialization of pf_enable is added.
> 
> Acked-by: Vlad Yasevich <vyasevich@gmail.com>
> Signed-off-by: Zhu Yanjun <zyjzyj2000@gmail.com>

Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>

> ---
>  Documentation/networking/ip-sysctl.txt |   23 ++++++++++++++++++++++-
>  include/net/netns/sctp.h               |    7 +++++++
>  net/sctp/protocol.c                    |    3 +++
>  net/sctp/sm_sideeffect.c               |    5 ++++-
>  net/sctp/sysctl.c                      |    7 +++++++
>  5 files changed, 43 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
> index 2ea4c45..f43ead3 100644
> --- a/Documentation/networking/ip-sysctl.txt
> +++ b/Documentation/networking/ip-sysctl.txt
> @@ -1723,6 +1723,25 @@ addip_enable - BOOLEAN
>  
>  	Default: 0
>  
> +pf_enable - INTEGER
> +	Enable or disable pf (pf is short for potentially failed) 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 occasionally 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. See:
> +	https://datatracker.ietf.org/doc/draft-ietf-tsvwg-sctp-failover for
> +	details.
> +
> +	1: Enable pf.
> +
> +	0: Disable pf.
> +
> +	Default: 1
> +
>  addip_noauth_enable - BOOLEAN
>  	Dynamic Address Reconfiguration (ADD-IP) requires the use of
>  	authentication to protect the operations of adding or removing new
> @@ -1799,7 +1818,9 @@ pf_retrans - INTEGER
>  	having to reduce path_max_retrans to a very low value.  See:
>  	http://www.ietf.org/id/draft-nishida-tsvwg-sctp-failover-05.txt
>  	for details.  Note also that a value of pf_retrans > path_max_retrans
> -	disables this feature
> +	disables this feature. Since both pf_retrans and path_max_retrans can
> +	be changed by userspace application, a variable pf_enable is used to
> +	disable pf state.
>  
>  	Default: 0
>  
> 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/protocol.c b/net/sctp/protocol.c
> index 3d9ea9a..cfbf49b 100644
> --- a/net/sctp/protocol.c
> +++ b/net/sctp/protocol.c
> @@ -1223,6 +1223,9 @@ static int __net_init sctp_defaults_init(struct net *net)
>  	/* Max.Burst		    - 4 */
>  	net->sctp.max_burst			= SCTP_DEFAULT_MAX_BURST;
>  
> +	/* Enable pf state by default */
> +	net->sctp.pf_enable = 1;
> +
>  	/* Association.Max.Retrans  - 10 attempts
>  	 * Path.Max.Retrans         - 5  attempts (per destination address)
>  	 * Max.Init.Retransmits     - 8  attempts
> diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
> index 6098d4c..05cd164 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..ccbfc93 100644
> --- a/net/sctp/sysctl.c
> +++ b/net/sctp/sysctl.c
> @@ -308,6 +308,13 @@ 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,
> +	},
>  
>  	{ /* sentinel */ }
>  };
> -- 
> 1.7.9.5
> 
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