netdev - RE: [PATCHv3 net-next 1/5] sctp: add SCTP_ADDR_POTENTIALLY

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Message-ID: <fb115b1444764b3eacdf69ebd9cf9681@AcuMS.aculab.com>
Date:   Fri, 18 Oct 2019 15:56:49 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Xin Long' <lucien.xin@...il.com>,
        network dev <netdev@...r.kernel.org>,
        "linux-sctp@...r.kernel.org" <linux-sctp@...r.kernel.org>
CC:     Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        Neil Horman <nhorman@...driver.com>,
        "davem@...emloft.net" <davem@...emloft.net>
Subject: RE: [PATCHv3 net-next 1/5] sctp: add SCTP_ADDR_POTENTIALLY_FAILED
 notification

I've found v3 :-)
But it isn't that much better than v2.

From: Xin Long
> Sent: 14 October 2019 07:15
> SCTP Quick failover draft section 5.1, point 5 has been removed
> from rfc7829. Instead, "the sender SHOULD (i) notify the Upper
> Layer Protocol (ULP) about this state transition", as said in
> section 3.2, point 8.
> 
> So this patch is to add SCTP_ADDR_POTENTIALLY_FAILED, defined
> in section 7.1, "which is reported if the affected address
> becomes PF". Also remove transport cwnd's update when moving
> from PF back to ACTIVE , which is no longer in rfc7829 either.
> 
> v1->v2:
>   - no change
> v2->v3:
>   - define SCTP_ADDR_PF SCTP_ADDR_POTENTIALLY_FAILED
> 
> Signed-off-by: Xin Long <lucien.xin@...il.com>
> ---
>  include/uapi/linux/sctp.h |  2 ++
>  net/sctp/associola.c      | 17 ++++-------------
>  2 files changed, 6 insertions(+), 13 deletions(-)
> 
> diff --git a/include/uapi/linux/sctp.h b/include/uapi/linux/sctp.h
> index 6bce7f9..f4ab7bb 100644
> --- a/include/uapi/linux/sctp.h
> +++ b/include/uapi/linux/sctp.h
> @@ -410,6 +410,8 @@ enum sctp_spc_state {
>  	SCTP_ADDR_ADDED,
>  	SCTP_ADDR_MADE_PRIM,
>  	SCTP_ADDR_CONFIRMED,
> +	SCTP_ADDR_POTENTIALLY_FAILED,
> +#define SCTP_ADDR_PF	SCTP_ADDR_POTENTIALLY_FAILED
>  };
> 
> 
> diff --git a/net/sctp/associola.c b/net/sctp/associola.c
> index 1ba893b..4f9efba 100644
> --- a/net/sctp/associola.c
> +++ b/net/sctp/associola.c
> @@ -801,14 +801,6 @@ void sctp_assoc_control_transport(struct sctp_association *asoc,
>  			spc_state = SCTP_ADDR_CONFIRMED;
>  		else
>  			spc_state = SCTP_ADDR_AVAILABLE;
> -		/* Don't inform ULP about transition from PF to
> -		 * active state and set cwnd to 1 MTU, see SCTP
> -		 * Quick failover draft section 5.1, point 5
> -		 */
> -		if (transport->state == SCTP_PF) {
> -			ulp_notify = false;
> -			transport->cwnd = asoc->pathmtu;
> -		}

This is wrong.
If the old state is PF and the application hasn't exposed PF the event should be
ignored.

>  		transport->state = SCTP_ACTIVE;
>  		break;
> 
> @@ -817,19 +809,18 @@ void sctp_assoc_control_transport(struct sctp_association *asoc,
>  		 * to inactive state.  Also, release the cached route since
>  		 * there may be a better route next time.
>  		 */
> -		if (transport->state != SCTP_UNCONFIRMED)
> +		if (transport->state != SCTP_UNCONFIRMED) {
>  			transport->state = SCTP_INACTIVE;
> -		else {
> +			spc_state = SCTP_ADDR_UNREACHABLE;
> +		} else {
>  			sctp_transport_dst_release(transport);
>  			ulp_notify = false;
>  		}
> -
> -		spc_state = SCTP_ADDR_UNREACHABLE;
>  		break;
> 
>  	case SCTP_TRANSPORT_PF:
>  		transport->state = SCTP_PF;
> -		ulp_notify = false;

Again the event should be supressed if PF isn't exposed.

> +		spc_state = SCTP_ADDR_POTENTIALLY_FAILED;
>  		break;
> 
>  	default:
> --
> 2.1.0

I also haven't spotted where the test that the application has actually enabled
state transition events is in the code.
I'd have thought it would be anything is built and allocated.

	David

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