From: Remi Gacogne <remi.gacogne@powerdns.com>
Date: Thu, 29 Apr 2021 11:26:24 +0000 (+0200)
Subject: dnsdist: Exclude the TCP latency calculations from TSAN analysis
X-Git-Tag: dnsdist-1.7.0-alpha1~45^2~34
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=ccff36b21cf751c10effb130381517362acc0dc2;p=thirdparty%2Fpdns.git

dnsdist: Exclude the TCP latency calculations from TSAN analysis

They are indeed racy in some cases, but we do not care about perfect
accuracy there.
---

diff --git a/pdns/dnsdist-tcp.cc b/pdns/dnsdist-tcp.cc
index 6653cee5dd..aa4a47d31d 100644
--- a/pdns/dnsdist-tcp.cc
+++ b/pdns/dnsdist-tcp.cc
@@ -347,6 +347,11 @@ static IOState sendQueuedResponses(std::shared_ptr<IncomingTCPConnectionState>&
   return IOState::Done;
 }
 
+static void updateTCPLatency(const std::shared_ptr<DownstreamState>& ds, double udiff)
+{
+  ds->latencyUsecTCP = (127.0 * ds->latencyUsecTCP / 128.0) + udiff/128.0;
+}
+
 static void handleResponseSent(std::shared_ptr<IncomingTCPConnectionState>& state, const TCPResponse& currentResponse)
 {
   if (currentResponse.d_idstate.qtype == QType::AXFR || currentResponse.d_idstate.qtype == QType::IXFR) {
@@ -363,7 +368,7 @@ static void handleResponseSent(std::shared_ptr<IncomingTCPConnectionState>& stat
 
     ::handleResponseSent(ids, udiff, state->d_ci.remote, ds->remote, static_cast<unsigned int>(currentResponse.d_buffer.size()), currentResponse.d_cleartextDH);
 
-    ds->latencyUsecTCP = (127.0 * ds->latencyUsecTCP / 128.0) + udiff/128.0;
+    updateTCPLatency(ds, udiff);
   }
 }
 
diff --git a/pdns/dnsdistdist/dnsdist-tsan.supp b/pdns/dnsdistdist/dnsdist-tsan.supp
index 0899dde574..39ffe6cd48 100644
--- a/pdns/dnsdistdist/dnsdist-tsan.supp
+++ b/pdns/dnsdistdist/dnsdist-tsan.supp
@@ -1,6 +1,7 @@
 # Part of that code has a race indeed, where we read the value then update it
 # We don't really care for these metrics
 race:doLatencyStats
+race:updateTCPLatency
 race:handleStats
 race:ClientState::updateTCPMetrics
 race:DownstreamState::updateTCPMetrics