commit 7d7afc64686d1442c736aa6493f0e61271365b2a
author Victor Boivie <boivie@webrtc.org> Wed Sep 22 10:14:26 2021
committer WebRTC LUCI CQ <webrtc-scoped@luci-project-accounts.iam.gserviceaccount.com> Wed Sep 22 13:27:37 2021
tree e4182739ded6768bd1ef3f19de45f13502d0a065
parent 9def99487e3b41a044ae4854ff620b8ff817f10f

dcsctp: Fix accidental re-use of variable

This was caused by change 231229 and was later caught when reviewing the
code. The rtt variable was accidentally re-used for another purpose, and
then assumed to still be used to represent the rtt.

There have been no issues found with this re-use, but it was wrong.

Bug: webrtc:12614
Change-Id: If1a180315cf833e293f78c54c3c3b29394a19a20
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/232610
Reviewed-by: Florent Castelli <orphis@webrtc.org>
Commit-Queue: Victor Boivie <boivie@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#35064}

net/dcsctp/tx/retransmission_timeout.cc

diff --git a/net/dcsctp/tx/retransmission_timeout.cc b/net/dcsctp/tx/retransmission_timeout.cc
index 2cb59f1..ee7c48b 100644
--- a/net/dcsctp/tx/retransmission_timeout.cc
+++ b/net/dcsctp/tx/retransmission_timeout.cc
@@ -23,7 +23,7 @@
       rto_(*options.rto_initial) {}
 
 void RetransmissionTimeout::ObserveRTT(DurationMs measured_rtt) {
-  int32_t rtt = *measured_rtt;
+  const int32_t rtt = *measured_rtt;
 
   // Unrealistic values will be skipped. If a wrongly measured (or otherwise
   // corrupt) value was processed, it could change the state in a way that would
@@ -40,13 +40,13 @@
     scaled_rtt_var_ = (rtt / 2) << kRttVarShift;
     first_measurement_ = false;
   } else {
-    rtt -= (scaled_srtt_ >> kRttShift);
-    scaled_srtt_ += rtt;
-    if (rtt < 0) {
-      rtt = -rtt;
+    int32_t rtt_diff = rtt - (scaled_srtt_ >> kRttShift);
+    scaled_srtt_ += rtt_diff;
+    if (rtt_diff < 0) {
+      rtt_diff = -rtt_diff;
     }
-    rtt -= (scaled_rtt_var_ >> kRttVarShift);
-    scaled_rtt_var_ += rtt;
+    rtt_diff -= (scaled_rtt_var_ >> kRttVarShift);
+    scaled_rtt_var_ += rtt_diff;
   }
   rto_ = (scaled_srtt_ >> kRttShift) + scaled_rtt_var_;