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Date: Fri, 21 Aug 2009 17:47:33 -0400
From: Vlad Yasevich <vladislav.yasevich@...com>
To: Chunbo Luo <chunbo.luo@...driver.com>
CC: davem@...emloft.net, netdev@...r.kernel.org,
linux-sctp@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] sctp: fix the check for path failure detection
Chunbo Luo wrote:
> The transport is marked DOWN immediately after sending the max+1 HB,
> which is equal to not sending the max+1 HB at all. We should wait
> a next period and make sure the last HB is not acknowledged.
>
I don't think this code does what you want either...
Let's say path_max_rxt = 2. What we'll get is:
timeout:
err++ (1)
if (err > 2) false
send HB
reset timer
timeout:
err++ (2)
if (err > 2) false
send HB
reset timer
timeout:
err++ (3)
if (err > 2)
set transport DOWN
send HB
reset timer.
We only had 2 unacknowledged HB when we should have had 3.
All you need to do is move the error error under a check that
makes sure that HB has been sent (similar to how the rto doubling
is done). Then you original patch would work where we change ">="
to simply ">". The error count will be max+1 when transport is marked DOWN.
-vlad
> Signed-off-by: Chunbo Luo <chunbo.luo@...driver.com>
> ---
> include/net/sctp/command.h | 1 +
> net/sctp/sm_sideeffect.c | 39 ++++++++++++++++++++++++++++-----------
> net/sctp/sm_statefuns.c | 16 ++++++++++++++--
> 3 files changed, 43 insertions(+), 13 deletions(-)
>
> diff --git a/include/net/sctp/command.h b/include/net/sctp/command.h
> index 3b96680..256effd 100644
> --- a/include/net/sctp/command.h
> +++ b/include/net/sctp/command.h
> @@ -77,6 +77,7 @@ typedef enum {
> SCTP_CMD_HB_TIMERS_START, /* Start the heartbeat timers. */
> SCTP_CMD_HB_TIMER_UPDATE, /* Update a heartbeat timers. */
> SCTP_CMD_HB_TIMERS_STOP, /* Stop the heartbeat timers. */
> + SCTP_CMD_PATH_FAILURE_DETECTION,/* Path failure detection. */
> SCTP_CMD_TRANSPORT_HB_SENT, /* Reset the status of a transport. */
> SCTP_CMD_TRANSPORT_IDLE, /* Do manipulations on idle transport */
> SCTP_CMD_TRANSPORT_ON, /* Mark the transport as active. */
> diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
> index 86426aa..db299c6 100644
> --- a/net/sctp/sm_sideeffect.c
> +++ b/net/sctp/sm_sideeffect.c
> @@ -432,7 +432,25 @@ sctp_timer_event_t *sctp_timer_events[SCTP_NUM_TIMEOUT_TYPES] = {
> * mark the destination transport address as inactive, and a
> * notification SHOULD be sent to the upper layer.
> *
> + * transport error counter is incremented in sctp_do_8_2_transport_strike
> */
> +static void sctp_cmd_path_failure_detection(struct sctp_association *asoc,
> + struct sctp_transport *transport)
> +{
> + if (transport->error_count > transport->pathmaxrxt) {
> + SCTP_DEBUG_PRINTK_IPADDR("transport_strike:association %p",
> + " transport IP: port:%d failed.\n",
> + asoc,
> + (&transport->ipaddr),
> + ntohs(transport->ipaddr.v4.sin_port));
> + sctp_assoc_control_transport(asoc, transport,
> + SCTP_TRANSPORT_DOWN,
> + SCTP_FAILED_THRESHOLD);
> + }
> +}
> +
> +
> + /* Mark a strike against a transport */
> static void sctp_do_8_2_transport_strike(struct sctp_association *asoc,
> struct sctp_transport *transport,
> int is_hb)
> @@ -446,17 +464,11 @@ static void sctp_do_8_2_transport_strike(struct sctp_association *asoc,
> if (transport->state != SCTP_UNCONFIRMED)
> asoc->overall_error_count++;
>
> - if (transport->state != SCTP_INACTIVE &&
> - (transport->error_count++ >= transport->pathmaxrxt)) {
> - SCTP_DEBUG_PRINTK_IPADDR("transport_strike:association %p",
> - " transport IP: port:%d failed.\n",
> - asoc,
> - (&transport->ipaddr),
> - ntohs(transport->ipaddr.v4.sin_port));
> - sctp_assoc_control_transport(asoc, transport,
> - SCTP_TRANSPORT_DOWN,
> - SCTP_FAILED_THRESHOLD);
> - }
> + /* The check for transport's error counter exceeding the threshold
> + * is done in the state function.
> + */
> + if (transport->state != SCTP_INACTIVE)
> + transport->error_count++;
>
> /* E2) For the destination address for which the timer
> * expires, set RTO <- RTO * 2 ("back off the timer"). The
> @@ -1464,6 +1476,11 @@ static int sctp_cmd_interpreter(sctp_event_t event_type,
> 0);
> break;
>
> + case SCTP_CMD_PATH_FAILURE_DETECTION:
> + t = cmd->obj.transport;
> + sctp_cmd_path_failure_detection(asoc, t);
> + break;
> +
> case SCTP_CMD_TRANSPORT_IDLE:
> t = cmd->obj.transport;
> sctp_transport_lower_cwnd(t, SCTP_LOWER_CWND_INACTIVE);
> diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
> index 7288192..f4c05fd 100644
> --- a/net/sctp/sm_statefuns.c
> +++ b/net/sctp/sm_statefuns.c
> @@ -981,6 +981,9 @@ sctp_disposition_t sctp_sf_sendbeat_8_3(const struct sctp_endpoint *ep,
> */
>
> if (transport->param_flags & SPP_HB_ENABLE) {
> + /* Do the path failure detection before send beat */
> + sctp_add_cmd_sf(commands, SCTP_CMD_PATH_FAILURE_DETECTION,
> + SCTP_TRANSPORT(transport));
> if (SCTP_DISPOSITION_NOMEM ==
> sctp_sf_heartbeat(ep, asoc, type, arg,
> commands))
> @@ -5229,6 +5232,8 @@ sctp_disposition_t sctp_sf_do_6_3_3_rtx(const struct sctp_endpoint *ep,
> */
>
> /* Do some failure management (Section 8.2). */
> + sctp_add_cmd_sf(commands, SCTP_CMD_PATH_FAILURE_DETECTION,
> + SCTP_TRANSPORT(transport));
> sctp_add_cmd_sf(commands, SCTP_CMD_STRIKE, SCTP_TRANSPORT(transport));
>
> /* NB: Rules E4 and F1 are implicit in R1. */
> @@ -5436,9 +5441,13 @@ sctp_disposition_t sctp_sf_t2_timer_expire(const struct sctp_endpoint *ep,
> * If we remove the transport an SHUTDOWN was last sent to, don't
> * do failure management.
> */
> - if (asoc->shutdown_last_sent_to)
> + if (asoc->shutdown_last_sent_to) {
> + sctp_add_cmd_sf(commands, SCTP_CMD_PATH_FAILURE_DETECTION,
> + SCTP_TRANSPORT(asoc->shutdown_last_sent_to));
> +
> sctp_add_cmd_sf(commands, SCTP_CMD_STRIKE,
> SCTP_TRANSPORT(asoc->shutdown_last_sent_to));
> + }
>
> /* Set the transport for the SHUTDOWN/ACK chunk and the timeout for
> * the T2-shutdown timer.
> @@ -5475,9 +5484,12 @@ sctp_disposition_t sctp_sf_t4_timer_expire(
> * detection on the appropriate destination address as defined in
> * RFC2960 [5] section 8.1 and 8.2.
> */
> - if (transport)
> + if (transport) {
> + sctp_add_cmd_sf(commands, SCTP_CMD_PATH_FAILURE_DETECTION,
> + SCTP_TRANSPORT(transport));
> sctp_add_cmd_sf(commands, SCTP_CMD_STRIKE,
> SCTP_TRANSPORT(transport));
> + }
>
> /* Reconfig T4 timer and transport. */
> sctp_add_cmd_sf(commands, SCTP_CMD_SETUP_T4, SCTP_CHUNK(chunk));
--
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