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-rw-r--r--net/sctp/transport.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/net/sctp/transport.c b/net/sctp/transport.c
index 0d48c61fe6ad..0c56d9673cc1 100644
--- a/net/sctp/transport.c
+++ b/net/sctp/transport.c
@@ -486,6 +486,7 @@ void sctp_transport_update_rto(struct sctp_transport *tp, __u32 rtt)
if (tp->rttvar || tp->srtt) {
struct net *net = tp->asoc->base.net;
+ unsigned int rto_beta, rto_alpha;
/* 6.3.1 C3) When a new RTT measurement R' is made, set
* RTTVAR <- (1 - RTO.Beta) * RTTVAR + RTO.Beta * |SRTT - R'|
* SRTT <- (1 - RTO.Alpha) * SRTT + RTO.Alpha * R'
@@ -497,10 +498,14 @@ void sctp_transport_update_rto(struct sctp_transport *tp, __u32 rtt)
* For example, assuming the default value of RTO.Alpha of
* 1/8, rto_alpha would be expressed as 3.
*/
- tp->rttvar = tp->rttvar - (tp->rttvar >> net->sctp.rto_beta)
- + (((__u32)abs((__s64)tp->srtt - (__s64)rtt)) >> net->sctp.rto_beta);
- tp->srtt = tp->srtt - (tp->srtt >> net->sctp.rto_alpha)
- + (rtt >> net->sctp.rto_alpha);
+ rto_beta = READ_ONCE(net->sctp.rto_beta);
+ if (rto_beta < 32)
+ tp->rttvar = tp->rttvar - (tp->rttvar >> rto_beta)
+ + (((__u32)abs((__s64)tp->srtt - (__s64)rtt)) >> rto_beta);
+ rto_alpha = READ_ONCE(net->sctp.rto_alpha);
+ if (rto_alpha < 32)
+ tp->srtt = tp->srtt - (tp->srtt >> rto_alpha)
+ + (rtt >> rto_alpha);
} else {
/* 6.3.1 C2) When the first RTT measurement R is made, set
* SRTT <- R, RTTVAR <- R/2.