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Message-ID: <20120720161001.1cc1bb10@obelix.rh>
Date: Fri, 20 Jul 2012 16:10:01 -0300
From: Flavio Leitner <fbl@...hat.com>
To: Neil Horman <nhorman@...driver.com>
Cc: netdev@...r.kernel.org, Vlad Yasevich <vyasevich@...il.com>,
Sridhar Samudrala <sri@...ibm.com>,
"David S. Miller" <davem@...emloft.net>,
linux-sctp@...r.kernel.org, joe@...ches.com
Subject: Re: [PATCH v5] sctp: Implement quick failover draft from tsvwg
On Fri, 20 Jul 2012 14:51:59 -0400
Neil Horman <nhorman@...driver.com> wrote:
> 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@...driver.com>
> CC: Vlad Yasevich <vyasevich@...il.com>
> CC: Sridhar Samudrala <sri@...ibm.com>
> CC: "David S. Miller" <davem@...emloft.net>
> CC: linux-sctp@...r.kernel.org
> CC: joe@...ches.com
>
> ---
> Change notes:
>
> V2)
> - Added socket option API from section 6.1 of the specification, as per
> request from Vlad. Adding this socket option allows us to alter both the path
> maximum retransmit value and the path partial failure threshold for each
> transport and the association as a whole.
>
> - Added a per transport pf_retrans value, and initialized it from the
> association value. This makes each transport independently configurable as per
> the socket option above, and prevents changes in the sysctl from bleeding into
> an already created association.
>
> V3)
> - Cleaned up some line spacing (Joe Perches)
> - Fixed some socket option user data sanitization (Vlad Yasevich)
>
> V4)
> - Added additional documentation (Flavio Leitner)
>
> V5)
> - Modified setsockopt option to ignore 0 pathmaxrxt rather than return
> error (Vlad Yasevich)
> - Modified getsocopt to return option length written (Vlad Y.)
> ---
> Documentation/networking/ip-sysctl.txt | 14 +++++
> include/net/sctp/constants.h | 1 +
> include/net/sctp/structs.h | 20 ++++++-
> include/net/sctp/user.h | 11 ++++
> net/sctp/associola.c | 37 ++++++++++--
> net/sctp/outqueue.c | 6 +-
> net/sctp/sm_sideeffect.c | 33 +++++++++-
> net/sctp/socket.c | 100 ++++++++++++++++++++++++++++++++
> net/sctp/sysctl.c | 9 +++
> net/sctp/transport.c | 4 +-
> 10 files changed, 220 insertions(+), 15 deletions(-)
>
> diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
> index 47b6c79..c636f9c 100644
> --- a/Documentation/networking/ip-sysctl.txt
> +++ b/Documentation/networking/ip-sysctl.txt
> @@ -1408,6 +1408,20 @@ path_max_retrans - INTEGER
>
> 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
> diff --git a/include/net/sctp/constants.h b/include/net/sctp/constants.h
> index 942b864..d053d2e 100644
> --- a/include/net/sctp/constants.h
> +++ b/include/net/sctp/constants.h
> @@ -334,6 +334,7 @@ typedef enum {
> 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
> diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
> index e4652fe..cee0678 100644
> --- a/include/net/sctp/structs.h
> +++ b/include/net/sctp/structs.h
> @@ -161,6 +161,12 @@ extern struct sctp_globals {
> 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
> @@ -258,6 +264,7 @@ extern struct sctp_globals {
> #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)
> @@ -987,10 +994,15 @@ struct sctp_transport {
>
> /* 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;
>
> @@ -1660,6 +1672,12 @@ struct sctp_association {
> */
> 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;
>
> diff --git a/include/net/sctp/user.h b/include/net/sctp/user.h
> index 0842ef0..1b02d7a 100644
> --- a/include/net/sctp/user.h
> +++ b/include/net/sctp/user.h
> @@ -93,6 +93,7 @@ typedef __s32 sctp_assoc_t;
> #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.
> @@ -649,6 +650,7 @@ struct sctp_paddrinfo {
> */
> enum sctp_spinfo_state {
> SCTP_INACTIVE,
> + SCTP_PF,
> SCTP_ACTIVE,
> SCTP_UNCONFIRMED,
> SCTP_UNKNOWN = 0xffff /* Value used for transport state unknown */
> @@ -741,4 +743,13 @@ typedef struct {
> 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__ */
> diff --git a/net/sctp/associola.c b/net/sctp/associola.c
> index 5bc9ab1..90fe36b 100644
> --- a/net/sctp/associola.c
> +++ b/net/sctp/associola.c
> @@ -124,6 +124,8 @@ static struct sctp_association *sctp_association_init(struct sctp_association *a
> * 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);
> @@ -685,6 +687,9 @@ struct sctp_transport *sctp_assoc_add_peer(struct sctp_association *asoc,
> /* 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.
> */
> @@ -840,6 +845,7 @@ void sctp_assoc_control_transport(struct sctp_association *asoc,
> struct sctp_ulpevent *event;
> struct sockaddr_storage addr;
> int spc_state = 0;
> + bool ulp_notify = true;
>
> /* Record the transition on the transport. */
> switch (command) {
> @@ -853,6 +859,14 @@ 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, 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;
>
> @@ -871,6 +885,11 @@ void sctp_assoc_control_transport(struct sctp_association *asoc,
> spc_state = SCTP_ADDR_UNREACHABLE;
> break;
>
> + case SCTP_TRANSPORT_PF:
> + transport->state = SCTP_PF;
> + ulp_notify = false;
> + break;
> +
> default:
> return;
> }
> @@ -878,12 +897,15 @@ void sctp_assoc_control_transport(struct sctp_association *asoc,
> /* 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. */
>
> @@ -899,7 +921,8 @@ void sctp_assoc_control_transport(struct sctp_association *asoc,
> 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 @@ static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
> 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 @@ static int sctp_outq_flush(struct sctp_outq *q, int rtx_timeout)
> 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 c96d1a8..285e26a 100644
> --- a/net/sctp/sm_sideeffect.c
> +++ b/net/sctp/sm_sideeffect.c
> @@ -76,6 +76,8 @@ static int sctp_side_effects(sctp_event_t event_type, sctp_subtype_t subtype,
> 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 @@ sctp_timer_event_t *sctp_timer_events[SCTP_NUM_TIMEOUT_TYPES] = {
> * 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 @@ static void sctp_do_8_2_transport_strike(struct sctp_association *asoc,
> 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 @@ static void sctp_cmd_transport_on(sctp_cmd_seq_t *cmds,
> 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 @@ static int sctp_cmd_interpreter(sctp_event_t event_type,
>
> 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 @@ static int sctp_cmd_interpreter(sctp_event_t event_type,
>
> 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 b3b8a8d..bba551f 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -3470,6 +3470,56 @@ static int sctp_setsockopt_auto_asconf(struct sock *sk, char __user *optval,
> }
>
>
> +/*
> + * 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
> @@ -3619,6 +3669,9 @@ SCTP_STATIC int sctp_setsockopt(struct sock *sk, int level, int optname,
> 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;
> @@ -5490,6 +5543,50 @@ static int sctp_getsockopt_assoc_ids(struct sock *sk, int len,
> 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 optlen)
> +{
> + struct sctp_paddrthlds val;
> + struct sctp_transport *trans;
> + struct sctp_association *asoc;
> +
> + if (optlen < sizeof(struct sctp_paddrthlds))
> + return -EINVAL;
> + optlen = sizeof(struct sctp_paddrthlds);
> + if (copy_from_user(&val, (struct sctp_paddrthlds __user *)optval, optlen))
> + 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 (copy_to_user(optval, &val, optlen))
> + return -EFAULT;
> +
> + return optlen;
> +}
> +
> SCTP_STATIC int sctp_getsockopt(struct sock *sk, int level, int optname,
> char __user *optval, int __user *optlen)
> {
> @@ -5628,6 +5725,9 @@ SCTP_STATIC int sctp_getsockopt(struct sock *sk, int level, int optname,
> 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);
> + 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 @@ static ctl_table sctp_table[] = {
> .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 b026ba0..194d0f3 100644
> --- a/net/sctp/transport.c
> +++ b/net/sctp/transport.c
> @@ -85,6 +85,7 @@ static struct sctp_transport *sctp_transport_init(struct sctp_transport *peer,
>
> /* 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);
> @@ -585,7 +586,8 @@ unsigned long sctp_transport_timeout(struct sctp_transport *t)
> {
> 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;
Reviewed-by: Flavio Leitner <fbl@...hat.com>
fbl
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