Merge branch 'sctp'

Daniel Borkmann says:

====================
Misc SCTP updates

Daniel Borkmann (2):
  net: sctp: improve timer slack calculation for transport HBs
  net: sctp: only warn in proc_sctp_do_alpha_beta if write
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Neil Horman <nhorman@tuxdriver.com>

2 files changed, 12 insertions, 10 deletions

diff --git a/net/sctp/sysctl.c b/net/sctp/sysctl.c
index 12c7e01c2677..2e9ada10fd84 100644
--- a/net/sctp/sysctl.c
+++ b/net/sctp/sysctl.c
@@ -424,8 +424,9 @@ static int proc_sctp_do_alpha_beta(struct ctl_table *ctl, int write,
                                    void __user *buffer, size_t *lenp,
                                    loff_t *ppos)
 {
-        pr_warn_once("Changing rto_alpha or rto_beta may lead to "
-                     "suboptimal rtt/srtt estimations!\n");
+        if (write)
+                pr_warn_once("Changing rto_alpha or rto_beta may lead to "
+                             "suboptimal rtt/srtt estimations!\n");
 
         return proc_dointvec_minmax(ctl, write, buffer, lenp, ppos);
 }
diff --git a/net/sctp/transport.c b/net/sctp/transport.c
index 7dd672fa651f..b10e047bbd15 100644
--- a/net/sctp/transport.c
+++ b/net/sctp/transport.c
@@ -594,15 +594,16 @@ void sctp_transport_burst_reset(struct sctp_transport *t)
 }
 
 /* What is the next timeout value for this transport? */
-unsigned long sctp_transport_timeout(struct sctp_transport *t)
+unsigned long sctp_transport_timeout(struct sctp_transport *trans)
 {
-        unsigned long timeout;
-        timeout = t->rto + sctp_jitter(t->rto);
-        if ((t->state != SCTP_UNCONFIRMED) &&
-            (t->state != SCTP_PF))
-                timeout += t->hbinterval;
-        timeout += jiffies;
-        return timeout;
+        /* RTO + timer slack +/- 50% of RTO */
+        unsigned long timeout = (trans->rto >> 1) + prandom_u32_max(trans->rto);
+
+        if (trans->state != SCTP_UNCONFIRMED &&
+            trans->state != SCTP_PF)
+                timeout += trans->hbinterval;
+
+        return timeout + jiffies;
 }
 
 /* Reset transport variables to their initial values */