3 files changed, 12 insertions, 31 deletions

diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
index 8e4de46c052e..c2035c96a2ee 100644
--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h
@@ -388,27 +388,6 @@ static inline int sctp_list_single_entry(struct list_head *head)
         return (head->next != head) && (head->next == head->prev);
 }
 
-/* Generate a random jitter in the range of -50% ~ +50% of input RTO. */
-static inline __s32 sctp_jitter(__u32 rto)
-{
-        static __u32 sctp_rand;
-        __s32 ret;
-
-        /* Avoid divide by zero. */
-        if (!rto)
-                rto = 1;
-
-        sctp_rand += jiffies;
-        sctp_rand ^= (sctp_rand << 12);
-        sctp_rand ^= (sctp_rand >> 20);
-
-        /* Choose random number from 0 to rto, then move to -50% ~ +50%
-         * of rto.
-         */
-        ret = sctp_rand % rto - (rto >> 1);
-        return ret;
-}
-
 /* Break down data chunks at this point.  */
 static inline int sctp_frag_point(const struct sctp_association *asoc, int pmtu)
 {
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 */