sctp: Implement quick failover draft from tsvwg
I've seen several attempts recently made to do quick failover of sctp transports
by reducing various retransmit timers and counters. While its possible to
implement a faster failover on multihomed sctp associations, its not
particularly robust, in that it can lead to unneeded retransmits, as well as
false connection failures due to intermittent latency on a network.
Instead, lets implement the new ietf quick failover draft found here:
http://tools.ietf.org/html/draft-nishida-tsvwg-sctp-failover-05
This will let the sctp stack identify transports that have had a small number of
errors, and avoid using them quickly until their reliability can be
re-established. I've tested this out on two virt guests connected via multiple
isolated virt networks and believe its in compliance with the above draft and
works well.
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Vlad Yasevich <vyasevich@gmail.com>
CC: Sridhar Samudrala <sri@us.ibm.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: linux-sctp@vger.kernel.org
CC: joe@perches.com
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/associola.c b/net/sctp/associola.c
index 8cf348e..ebaef3e 100644
--- a/net/sctp/associola.c
+++ b/net/sctp/associola.c
@@ -124,6 +124,8 @@
* socket values.
*/
asoc->max_retrans = sp->assocparams.sasoc_asocmaxrxt;
+ asoc->pf_retrans = sctp_pf_retrans;
+
asoc->rto_initial = msecs_to_jiffies(sp->rtoinfo.srto_initial);
asoc->rto_max = msecs_to_jiffies(sp->rtoinfo.srto_max);
asoc->rto_min = msecs_to_jiffies(sp->rtoinfo.srto_min);
@@ -686,6 +688,9 @@
/* Set the path max_retrans. */
peer->pathmaxrxt = asoc->pathmaxrxt;
+ /* And the partial failure retrnas threshold */
+ peer->pf_retrans = asoc->pf_retrans;
+
/* Initialize the peer's SACK delay timeout based on the
* association configured value.
*/
@@ -841,6 +846,7 @@
struct sctp_ulpevent *event;
struct sockaddr_storage addr;
int spc_state = 0;
+ bool ulp_notify = true;
/* Record the transition on the transport. */
switch (command) {
@@ -854,6 +860,14 @@
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, see SCTP
+ * Quick failover draft section 5.1, point 5
+ */
+ if (transport->state == SCTP_PF) {
+ ulp_notify = false;
+ transport->cwnd = 1;
+ }
transport->state = SCTP_ACTIVE;
break;
@@ -872,6 +886,11 @@
spc_state = SCTP_ADDR_UNREACHABLE;
break;
+ case SCTP_TRANSPORT_PF:
+ transport->state = SCTP_PF;
+ ulp_notify = false;
+ break;
+
default:
return;
}
@@ -879,12 +898,15 @@
/* Generate and send a SCTP_PEER_ADDR_CHANGE notification to the
* user.
*/
- memset(&addr, 0, sizeof(struct sockaddr_storage));
- memcpy(&addr, &transport->ipaddr, transport->af_specific->sockaddr_len);
- event = sctp_ulpevent_make_peer_addr_change(asoc, &addr,
- 0, spc_state, error, GFP_ATOMIC);
- if (event)
- sctp_ulpq_tail_event(&asoc->ulpq, event);
+ if (ulp_notify) {
+ memset(&addr, 0, sizeof(struct sockaddr_storage));
+ memcpy(&addr, &transport->ipaddr,
+ transport->af_specific->sockaddr_len);
+ event = sctp_ulpevent_make_peer_addr_change(asoc, &addr,
+ 0, spc_state, error, GFP_ATOMIC);
+ if (event)
+ sctp_ulpq_tail_event(&asoc->ulpq, event);
+ }
/* Select new active and retran paths. */
@@ -900,7 +922,8 @@
transports) {
if ((t->state == SCTP_INACTIVE) ||
- (t->state == SCTP_UNCONFIRMED))
+ (t->state == SCTP_UNCONFIRMED) ||
+ (t->state == SCTP_PF))
continue;
if (!first || t->last_time_heard > first->last_time_heard) {
second = first;
diff --git a/net/sctp/outqueue.c b/net/sctp/outqueue.c
index a0fa19f..e7aa177c 100644
--- a/net/sctp/outqueue.c
+++ b/net/sctp/outqueue.c
@@ -792,7 +792,8 @@
if (!new_transport)
new_transport = asoc->peer.active_path;
} else if ((new_transport->state == SCTP_INACTIVE) ||
- (new_transport->state == SCTP_UNCONFIRMED)) {
+ (new_transport->state == SCTP_UNCONFIRMED) ||
+ (new_transport->state == SCTP_PF)) {
/* If the chunk is Heartbeat or Heartbeat Ack,
* send it to chunk->transport, even if it's
* inactive.
@@ -987,7 +988,8 @@
new_transport = chunk->transport;
if (!new_transport ||
((new_transport->state == SCTP_INACTIVE) ||
- (new_transport->state == SCTP_UNCONFIRMED)))
+ (new_transport->state == SCTP_UNCONFIRMED) ||
+ (new_transport->state == SCTP_PF)))
new_transport = asoc->peer.active_path;
if (new_transport->state == SCTP_UNCONFIRMED)
continue;
diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
index 8716da1..fe99628 100644
--- a/net/sctp/sm_sideeffect.c
+++ b/net/sctp/sm_sideeffect.c
@@ -76,6 +76,8 @@
sctp_cmd_seq_t *commands,
gfp_t gfp);
+static void sctp_cmd_hb_timer_update(sctp_cmd_seq_t *cmds,
+ struct sctp_transport *t);
/********************************************************************
* Helper functions
********************************************************************/
@@ -470,7 +472,8 @@
* notification SHOULD be sent to the upper layer.
*
*/
-static void sctp_do_8_2_transport_strike(struct sctp_association *asoc,
+static void sctp_do_8_2_transport_strike(sctp_cmd_seq_t *commands,
+ struct sctp_association *asoc,
struct sctp_transport *transport,
int is_hb)
{
@@ -495,6 +498,23 @@
transport->error_count++;
}
+ /* If the transport error count is greater than the pf_retrans
+ * threshold, and less than pathmaxrtx, then mark this transport
+ * as Partially Failed, ee SCTP Quick Failover Draft, secon 5.1,
+ * point 1
+ */
+ if ((transport->state != SCTP_PF) &&
+ (asoc->pf_retrans < transport->pathmaxrxt) &&
+ (transport->error_count > asoc->pf_retrans)) {
+
+ sctp_assoc_control_transport(asoc, transport,
+ SCTP_TRANSPORT_PF,
+ 0);
+
+ /* Update the hb timer to resend a heartbeat every rto */
+ sctp_cmd_hb_timer_update(commands, transport);
+ }
+
if (transport->state != SCTP_INACTIVE &&
(transport->error_count > transport->pathmaxrxt)) {
SCTP_DEBUG_PRINTK_IPADDR("transport_strike:association %p",
@@ -699,6 +719,10 @@
SCTP_HEARTBEAT_SUCCESS);
}
+ if (t->state == SCTP_PF)
+ sctp_assoc_control_transport(asoc, t, SCTP_TRANSPORT_UP,
+ SCTP_HEARTBEAT_SUCCESS);
+
/* The receiver of the HEARTBEAT ACK should also perform an
* RTT measurement for that destination transport address
* using the time value carried in the HEARTBEAT ACK chunk.
@@ -1565,8 +1589,8 @@
case SCTP_CMD_STRIKE:
/* Mark one strike against a transport. */
- sctp_do_8_2_transport_strike(asoc, cmd->obj.transport,
- 0);
+ sctp_do_8_2_transport_strike(commands, asoc,
+ cmd->obj.transport, 0);
break;
case SCTP_CMD_TRANSPORT_IDLE:
@@ -1576,7 +1600,8 @@
case SCTP_CMD_TRANSPORT_HB_SENT:
t = cmd->obj.transport;
- sctp_do_8_2_transport_strike(asoc, t, 1);
+ sctp_do_8_2_transport_strike(commands, asoc,
+ t, 1);
t->hb_sent = 1;
break;
diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 5d488cd..5e25981 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -3478,6 +3478,56 @@
}
+/*
+ * SCTP_PEER_ADDR_THLDS
+ *
+ * This option allows us to alter the partially failed threshold for one or all
+ * transports in an association. See Section 6.1 of:
+ * http://www.ietf.org/id/draft-nishida-tsvwg-sctp-failover-05.txt
+ */
+static int sctp_setsockopt_paddr_thresholds(struct sock *sk,
+ char __user *optval,
+ unsigned int optlen)
+{
+ struct sctp_paddrthlds val;
+ struct sctp_transport *trans;
+ struct sctp_association *asoc;
+
+ if (optlen < sizeof(struct sctp_paddrthlds))
+ return -EINVAL;
+ if (copy_from_user(&val, (struct sctp_paddrthlds __user *)optval,
+ sizeof(struct sctp_paddrthlds)))
+ return -EFAULT;
+
+
+ if (sctp_is_any(sk, (const union sctp_addr *)&val.spt_address)) {
+ asoc = sctp_id2assoc(sk, val.spt_assoc_id);
+ if (!asoc)
+ return -ENOENT;
+ list_for_each_entry(trans, &asoc->peer.transport_addr_list,
+ transports) {
+ if (val.spt_pathmaxrxt)
+ trans->pathmaxrxt = val.spt_pathmaxrxt;
+ trans->pf_retrans = val.spt_pathpfthld;
+ }
+
+ if (val.spt_pathmaxrxt)
+ asoc->pathmaxrxt = val.spt_pathmaxrxt;
+ asoc->pf_retrans = val.spt_pathpfthld;
+ } else {
+ trans = sctp_addr_id2transport(sk, &val.spt_address,
+ val.spt_assoc_id);
+ if (!trans)
+ return -ENOENT;
+
+ if (val.spt_pathmaxrxt)
+ trans->pathmaxrxt = val.spt_pathmaxrxt;
+ trans->pf_retrans = val.spt_pathpfthld;
+ }
+
+ return 0;
+}
+
/* API 6.2 setsockopt(), getsockopt()
*
* Applications use setsockopt() and getsockopt() to set or retrieve
@@ -3627,6 +3677,9 @@
case SCTP_AUTO_ASCONF:
retval = sctp_setsockopt_auto_asconf(sk, optval, optlen);
break;
+ case SCTP_PEER_ADDR_THLDS:
+ retval = sctp_setsockopt_paddr_thresholds(sk, optval, optlen);
+ break;
default:
retval = -ENOPROTOOPT;
break;
@@ -5498,6 +5551,51 @@
return 0;
}
+/*
+ * SCTP_PEER_ADDR_THLDS
+ *
+ * This option allows us to fetch the partially failed threshold for one or all
+ * transports in an association. See Section 6.1 of:
+ * http://www.ietf.org/id/draft-nishida-tsvwg-sctp-failover-05.txt
+ */
+static int sctp_getsockopt_paddr_thresholds(struct sock *sk,
+ char __user *optval,
+ int len,
+ int __user *optlen)
+{
+ struct sctp_paddrthlds val;
+ struct sctp_transport *trans;
+ struct sctp_association *asoc;
+
+ if (len < sizeof(struct sctp_paddrthlds))
+ return -EINVAL;
+ len = sizeof(struct sctp_paddrthlds);
+ if (copy_from_user(&val, (struct sctp_paddrthlds __user *)optval, len))
+ return -EFAULT;
+
+ if (sctp_is_any(sk, (const union sctp_addr *)&val.spt_address)) {
+ asoc = sctp_id2assoc(sk, val.spt_assoc_id);
+ if (!asoc)
+ return -ENOENT;
+
+ val.spt_pathpfthld = asoc->pf_retrans;
+ val.spt_pathmaxrxt = asoc->pathmaxrxt;
+ } else {
+ trans = sctp_addr_id2transport(sk, &val.spt_address,
+ val.spt_assoc_id);
+ if (!trans)
+ return -ENOENT;
+
+ val.spt_pathmaxrxt = trans->pathmaxrxt;
+ val.spt_pathpfthld = trans->pf_retrans;
+ }
+
+ if (put_user(len, optlen) || copy_to_user(optval, &val, len))
+ return -EFAULT;
+
+ return 0;
+}
+
SCTP_STATIC int sctp_getsockopt(struct sock *sk, int level, int optname,
char __user *optval, int __user *optlen)
{
@@ -5636,6 +5734,9 @@
case SCTP_AUTO_ASCONF:
retval = sctp_getsockopt_auto_asconf(sk, len, optval, optlen);
break;
+ case SCTP_PEER_ADDR_THLDS:
+ retval = sctp_getsockopt_paddr_thresholds(sk, optval, len, optlen);
+ break;
default:
retval = -ENOPROTOOPT;
break;
diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c
index e5fe639..2b2bfe9 100644
--- a/net/sctp/sysctl.c
+++ b/net/sctp/sysctl.c
@@ -141,6 +141,15 @@
.extra2 = &int_max
},
{
+ .procname = "pf_retrans",
+ .data = &sctp_pf_retrans,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &zero,
+ .extra2 = &int_max
+ },
+ {
.procname = "max_init_retransmits",
.data = &sctp_max_retrans_init,
.maxlen = sizeof(int),
diff --git a/net/sctp/transport.c b/net/sctp/transport.c
index a6b7ee9..d1c652e 100644
--- a/net/sctp/transport.c
+++ b/net/sctp/transport.c
@@ -87,6 +87,7 @@
/* Initialize the default path max_retrans. */
peer->pathmaxrxt = sctp_max_retrans_path;
+ peer->pf_retrans = sctp_pf_retrans;
INIT_LIST_HEAD(&peer->transmitted);
INIT_LIST_HEAD(&peer->send_ready);
@@ -595,7 +596,8 @@
{
unsigned long timeout;
timeout = t->rto + sctp_jitter(t->rto);
- if (t->state != SCTP_UNCONFIRMED)
+ if ((t->state != SCTP_UNCONFIRMED) &&
+ (t->state != SCTP_PF))
timeout += t->hbinterval;
timeout += jiffies;
return timeout;
