Re: [PATCH 4/4] sctp: heartbeats exceed maximum retransmssion limit

[Vlad Yasevich <vladislav.yasevich@hp.com>]

Wei Yongjun wrote:
> The number of HEARTBEAT chunks that an association may transmit is
> limited by Association.Max.Retrans count; however, the code allows
> us to send one extra heartbeat.
> 
> This patch limits the number of heartbeats to the maximum count.
> 
> Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
> ---
>  net/sctp/sm_statefuns.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
> index 3e7f6d2..ac7bf6d 100644
> --- a/net/sctp/sm_statefuns.c
> +++ b/net/sctp/sm_statefuns.c
> @@ -962,7 +962,7 @@ sctp_disposition_t sctp_sf_sendbeat_8_3(const struct sctp_endpoint *ep,
>  {
>  	struct sctp_transport *transport = (struct sctp_transport *) arg;
>  
> -	if (asoc->overall_error_count > asoc->max_retrans) {
> +	if (asoc->overall_error_count >= asoc->max_retrans) {
>  		sctp_add_cmd_sf(commands, SCTP_CMD_SET_SK_ERR,
>  				SCTP_ERROR(ETIMEDOUT));
>  		/* CMD_ASSOC_FAILED calls CMD_DELETE_TCB. */

Hi Wei

Here is the spec:

   The endpoint should increment the respective error counter of the
   destination transport address each time a HEARTBEAT is sent to that
   address and not acknowledged within one RTO.

   When the value of this counter reaches the protocol parameter
   'Path.Max.Retrans', the endpoint should mark the corresponding
   destination address as inactive...

According to this, only unacknowledged HB count as errors.  The very
first HB we sent doest count as an error until the RTO expires.  So
the >= is the correct test here as we are really counting the number
of timeouts with reacknowledgment.

-vlad