The calculation of RTTVAR involves the subtraction of two unsigned
numbers which
may causes rollover and results in very high values of RTTVAR when RTT > SRTT.
With this patch it is possible to set RTOmin = 1 to get the minimum of RTO at
4 times the clock granularity.
Change Notes:
v2)
*Replaced abs() by abs64() and long by __s64, changed patch
description.
Signed-off-by: Christian Schoch <e0326715@xxxxxxxxxxxxxxxxxxxx>
CC: Vlad Yasevich <vyasevich@xxxxxxxxx>
CC: Sridhar Samudrala <sri@xxxxxxxxxx>
CC: Neil Horman <nhorman@xxxxxxxxxxxxx>
CC: linux-sctp@xxxxxxxxxxxxxxx
---
diff --git a/net/sctp/transport.c b/net/sctp/transport.c
index 953c21e..206cf52 100644
--- a/net/sctp/transport.c
+++ b/net/sctp/transport.c
@@ -331,7 +331,7 @@ void sctp_transport_update_rto(struct
sctp_transport *tp, __u32 rtt)
* 1/8, rto_alpha would be expressed as 3.
*/
tp->rttvar = tp->rttvar - (tp->rttvar >> net->sctp.rto_beta)
- + ((abs(tp->srtt - rtt)) >> net->sctp.rto_beta);
+ + (((__u32)abs64((__s64)tp->srtt -
(__s64)rtt)) >> net->sctp.rto_beta);
tp->srtt = tp->srtt - (tp->srtt >> net->sctp.rto_alpha)
+ (rtt >> net->sctp.rto_alpha);
} else {
--
--
To unsubscribe from this list: send the line "unsubscribe linux-sctp" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
