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authorSchoch Christian <e0326715@student.tuwien.ac.at>2012-11-28 05:18:29 +0000
committerDavid S. Miller <davem@davemloft.net>2012-11-28 11:13:40 -0500
commit92d64c261e77cb2a6117887617e2a629fea6b67c (patch)
tree0021d03d1c34acb7ab099ad66bbec6f28d658613 /net/sctp
parent6e51fe7572590d8d86e93b547fab6693d305fd0d (diff)
sctp: Error in calculation of RTTvar
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@student.tuwien.ac.at> CC: Vlad Yasevich <vyasevich@gmail.com> CC: Sridhar Samudrala <sri@us.ibm.com> CC: Neil Horman <nhorman@tuxdriver.com> CC: linux-sctp@vger.kernel.org Acked-by: Vlad Yasevich <vyasevich@gmail.com> Acked-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/sctp')
-rw-r--r--net/sctp/transport.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/net/sctp/transport.c b/net/sctp/transport.c
index 953c21e4af97..206cf5238fd3 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 {