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>
Default: 5
+pf_retrans - INTEGER
+ The number of retransmissions that will be attempted on a given path
+ before traffic is redirected to an alternate transport (should one
+ exist). Note this is distinct from path_max_retrans, as a path that
+ passes the pf_retrans threshold can still be used. Its only
+ deprioritized when a transmission path is selected by the stack. This
+ setting is primarily used to enable fast failover mechanisms without
+ 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
+
+ Default: 0
+
rto_initial - INTEGER
The initial round trip timeout value in milliseconds that will be used
in calculating round trip times. This is the initial time interval
typedef enum {
SCTP_TRANSPORT_UP,
SCTP_TRANSPORT_DOWN,
+ SCTP_TRANSPORT_PF,
} sctp_transport_cmd_t;
/* These are the address scopes defined mainly for IPv4 addresses
int max_retrans_path;
int max_retrans_init;
+ /* Potentially-Failed.Max.Retrans sysctl value
+ * taken from:
+ * http://tools.ietf.org/html/draft-nishida-tsvwg-sctp-failover-05
+ */
+ int pf_retrans;
+
/*
* Policy for preforming sctp/socket accounting
* 0 - do socket level accounting, all assocs share sk_sndbuf
#define sctp_sndbuf_policy (sctp_globals.sndbuf_policy)
#define sctp_rcvbuf_policy (sctp_globals.rcvbuf_policy)
#define sctp_max_retrans_path (sctp_globals.max_retrans_path)
+#define sctp_pf_retrans (sctp_globals.pf_retrans)
#define sctp_max_retrans_init (sctp_globals.max_retrans_init)
#define sctp_sack_timeout (sctp_globals.sack_timeout)
#define sctp_hb_interval (sctp_globals.hb_interval)
/* This is the max_retrans value for the transport and will
* be initialized from the assocs value. This can be changed
- * using SCTP_SET_PEER_ADDR_PARAMS socket option.
+ * using the SCTP_SET_PEER_ADDR_PARAMS socket option.
*/
__u16 pathmaxrxt;
+ /* This is the partially failed retrans value for the transport
+ * and will be initialized from the assocs value. This can be changed
+ * using the SCTP_PEER_ADDR_THLDS socket option
+ */
+ int pf_retrans;
/* PMTU : The current known path MTU. */
__u32 pathmtu;
*/
int max_retrans;
+ /* This is the partially failed retrans value for the transport
+ * and will be initialized from the assocs value. This can be
+ * changed using the SCTP_PEER_ADDR_THLDS socket option
+ */
+ int pf_retrans;
+
/* Maximum number of times the endpoint will retransmit INIT */
__u16 max_init_attempts;
#define SCTP_GET_ASSOC_NUMBER 28 /* Read only */
#define SCTP_GET_ASSOC_ID_LIST 29 /* Read only */
#define SCTP_AUTO_ASCONF 30
+#define SCTP_PEER_ADDR_THLDS 31
/* Internal Socket Options. Some of the sctp library functions are
* implemented using these socket options.
*/
enum sctp_spinfo_state {
SCTP_INACTIVE,
+ SCTP_PF,
SCTP_ACTIVE,
SCTP_UNCONFIRMED,
SCTP_UNKNOWN = 0xffff /* Value used for transport state unknown */
int sd;
} sctp_peeloff_arg_t;
+/*
+ * Peer Address Thresholds socket option
+ */
+struct sctp_paddrthlds {
+ sctp_assoc_t spt_assoc_id;
+ struct sockaddr_storage spt_address;
+ __u16 spt_pathmaxrxt;
+ __u16 spt_pathpfthld;
+};
#endif /* __net_sctp_user_h__ */
* 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);
/* 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.
*/
struct sctp_ulpevent *event;
struct sockaddr_storage addr;
int spc_state = 0;
+ bool ulp_notify = true;
/* Record the transition on the transport. */
switch (command) {
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;
spc_state = SCTP_ADDR_UNREACHABLE;
break;
+ case SCTP_TRANSPORT_PF:
+ transport->state = SCTP_PF;
+ ulp_notify = false;
+ break;
+
default:
return;
}
/* 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. */
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;
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.
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;
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
********************************************************************/
* 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)
{
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",
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.
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:
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;
}
+/*
+ * 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
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;
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)
{
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;
.extra1 = &one,
.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,
/* 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);
{
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;
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