Fix a time race in Time-HiRes/t/itimer.t test

perl-5.29.1-Time-HiRes-t-itimer.t-avoid-race-condition.patch

@@ -0,0 +1,54 @@
+From ecbf46993f6ffbdc255f6ded3c6c05a8266a71e8 Mon Sep 17 00:00:00 2001
+From: David Mitchell <davem@iabyn.com>
+Date: Tue, 7 Aug 2018 12:26:31 +0100
+Subject: [PATCH] Time-HiRes/t/itimer.t: avoid race condition.
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+This test script sets a repeating interval timer going, and after 4
+'ticks' (SIGVTALRM), disables the timer (by setting it to zero).
+
+The main loop which does CPU burning, does a getitmer() every now and
+again, and when the value is zero, assumes the signal handler has
+disabled the timer,  and so finishes.
+
+The trouble was that it was checking the 'time left', which can reach
+zero because the interval timer has counted down to zero, and the signal
+handler is about to be called, but the interval hasn't been reset back
+to 0.4s yet.
+
+i.e. the code doesn't distinguish between "timer disabled" and "timer
+just reached zero".
+
+In that scenario, the cleanup code in the test script disables the
+SIGVTALRM handler while the timer is still active, and so the process
+gets killed if another signal is raised.
+
+This commit changes the test to check the second value returned by
+getitmer() for being zero rather than the first - the second being the
+repeat interval, whichb is always 0.4 until the timer is disabled.
+
+Signed-off-by: Petr Písař <ppisar@redhat.com>
+---
+ dist/Time-HiRes/t/itimer.t | 4 +++-
+ 1 file changed, 3 insertions(+), 1 deletion(-)
+
+diff --git a/dist/Time-HiRes/t/itimer.t b/dist/Time-HiRes/t/itimer.t
+index e196b1648c..432b224488 100644
+--- a/dist/Time-HiRes/t/itimer.t
++++ b/dist/Time-HiRes/t/itimer.t
+@@ -51,7 +51,9 @@ ok(defined $virt && abs($virt / 0.5) - 1 < $limit,
+ printf("# getitimer: %s\n", join(" ",
+        Time::HiRes::getitimer(&Time::HiRes::ITIMER_VIRTUAL)));
+ 
+-while (Time::HiRes::getitimer(&Time::HiRes::ITIMER_VIRTUAL)) {
++# burn CPU until the VTALRM signal handler sets the repeat interval to
++# zero, indicating that the timer has fired 4 times.
++while ((Time::HiRes::getitimer(&Time::HiRes::ITIMER_VIRTUAL))[1]) {
+     my $j;
+     for (1..1000) { $j++ } # Can't be unbreakable, must test getitimer().
+ }
+-- 
+2.14.4
+

perl.spec

@@ -187,6 +187,9 @@ Patch24:        perl-5.29.0-Make-utf8_to_uvchr-safer.patch
 Patch25:        perl-5.29.0-Fix-VC6-build-following-commit-aa3c16bd70.patch
 Patch26:        perl-5.29.1-Make-utf8_to_uvchr-slightly-safer.patch
 
+# Fix a time race in Time-HiRes/t/itimer.t test, in upstream after 5.29.1
+Patch27:        perl-5.29.1-Time-HiRes-t-itimer.t-avoid-race-condition.patch
+
 # Link XS modules to libperl.so with EU::CBuilder on Linux, bug #960048
 Patch200:       perl-5.16.3-Link-XS-modules-to-libperl.so-with-EU-CBuilder-on-Li.patch
 
@@ -2765,6 +2768,7 @@ Perl extension for Version Objects
 %patch24 -p1
 %patch25 -p1
 %patch26 -p1
+%patch27 -p1
 %patch200 -p1
 %patch201 -p1
 
@@ -2798,6 +2802,7 @@ perl -x patchlevel.h \
     'Fedora Patch24: Fix a buffer overrun in deprecated utf8_to_uvchr()' \
     'Fedora Patch25: Fix a buffer overrun in deprecated utf8_to_uvchr()' \
     'Fedora Patch26: Fix a buffer overrun in deprecated utf8_to_uvchr()' \
+    'Fedora Patch27: Fix a time race in Time-HiRes/t/itimer.t test' \
     'Fedora Patch200: Link XS modules to libperl.so with EU::CBuilder on Linux' \
     'Fedora Patch201: Link XS modules to libperl.so with EU::MM on Linux' \
     %{nil}
@@ -5089,6 +5094,7 @@ popd
 * Wed Sep 05 2018 Petr Pisar <ppisar@redhat.com> - 4:5.28.0-421
 - Fix a buffer overrun in deprecated S_is_utf8_common()
 - Fix a buffer overrun in deprecated utf8_to_uvchr()
+- Fix a time race in Time-HiRes/t/itimer.t test
 
 * Wed Aug 01 2018 Petr Pisar <ppisar@redhat.com> - 4:5.28.0-420
 - Fix a file descriptor leak in in-place edits (RT#133314)