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Message-ID: <ab3918ef-84db-413c-93d7-c3b9afe8fa87@email.android.com>
Date: Sat, 21 Jul 2012 02:45:03 -0400
From: Vlad Yasevich <vyasevich@...il.com>
To: Neil Horman <nhorman@...driver.com>, netdev@...r.kernel.org
CC: 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
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(-)
>
>> /* 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;
I don't think you can simply return this. You have to call put_user() with the value to write it back to the User. See how other get calls are done.
-Vlad
>+}
>+
>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;
>--
>1.7.7.6
--
Sent from my Android phone with SkitMail. Please excuse my brevity.
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