From: Miroslav Lichvar <mlichvar@redhat.com>
Date: Wed, 28 Aug 2024 08:49:52 +0000 (+0200)
Subject: sources: replace unreachable sources before selection
X-Git-Tag: 4.6~6
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=78b9c13a11b63348a2060b8f3b55662b3ec2c814;p=thirdparty%2Fchrony.git

sources: replace unreachable sources before selection

The commit c43efccf0273 ("sources: update source selection with
unreachable sources") caused a high rate of failures in the
148-replacement test (1 falseticker vs 2 unreachable sources). This was
due to a larger fraction of the replacement attempts being made for the
source incorrectly marked as a falseticker instead of the second
unreachable source and the random process needed more time to get to the
expected state with both unreachable sources replaced.

When updating reachability of an unreachable source, try to request the
replacement of the source before calling the source selection, where
other sources may be replaced, to better balance the different
replacement attempts.
---

diff --git a/sources.c b/sources.c
index 26144484..ff7a7925 100644
--- a/sources.c
+++ b/sources.c
@@ -526,11 +526,6 @@ SRC_UpdateReachability(SRC_Instance inst, int reachable)
   if (inst->reachability_size < SOURCE_REACH_BITS)
       inst->reachability_size++;
 
-  /* Source selection can change with unreachable sources */
-  if (inst->reachability == 0) {
-    SRC_SelectSource(NULL);
-  }
-
   /* Check if special reference update mode failed */
   if (REF_GetMode() != REF_ModeNormal && special_mode_end()) {
     REF_SetUnsynchronised();
@@ -539,6 +534,10 @@ SRC_UpdateReachability(SRC_Instance inst, int reachable)
   /* Try to replace unreachable NTP sources */
   if (inst->reachability == 0 && inst->reachability_size == SOURCE_REACH_BITS)
     handle_bad_source(inst);
+
+  /* Source selection can change with unreachable sources */
+  if (inst->reachability == 0)
+    SRC_SelectSource(NULL);
 }
 
 /* ================================================== */
diff --git a/test/simulation/148-replacement b/test/simulation/148-replacement
index f15fc4d3..d09fba6e 100755
--- a/test/simulation/148-replacement
+++ b/test/simulation/148-replacement
@@ -53,4 +53,28 @@ check_log_messages "2010-01-01T0[5-9]:.*Source 192.168.123.. replaced with" 0 15
 check_file_messages "20.*192.168.123.* 11.1   6  6 " 20 500 measurements.log || test_fail
 rm -f tmp/measurements.log
 
+# 2 replaceable falsetickers and 1 replaceable unreachable server
+servers=6
+falsetickers=2
+base_delay="(+ 1e-4 (* -1 (equal 0.1 to 3)))"
+client_server_conf="
+server nodes-4-1.net1.clk
+server nodes-5-2.net1.clk
+server nodes-6-3.net1.clk"
+
+run_test || test_fail
+check_chronyd_exit || test_fail
+check_source_selection && test_fail
+check_packet_interval || test_fail
+check_sync || test_fail
+
+check_log_messages "Can't synchronise: no majority" 1 1 || test_fail
+check_log_messages "Detected falseticker" 0 2 || test_fail
+check_log_messages "Source 192.168.123.. replaced with" 3 60 || test_fail
+check_log_messages "Source 192.168.123.1 replaced with" 1 25 || test_fail
+check_log_messages "Source 192.168.123.2 replaced with" 1 25 || test_fail
+check_log_messages "Source 192.168.123.3 replaced with" 1 25 || test_fail
+check_file_messages "20.*192.168.123.* 11.1   6  6 " 50 800 measurements.log || test_fail
+rm -f tmp/measurements.log
+
 test_pass