torture: Abstract jitter.sh start/stop into scripts

This commit creates jitterstart.sh and jitterstop.sh scripts that handle
the starting and stopping of the jitter.sh scripts.  These must be sourced
using the bash "." command to allow the generated script to wait on the
backgrounded jitter.sh scripts.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

3 files changed, 62 insertions, 5 deletions

diff --git a/tools/testing/selftests/rcutorture/bin/jitterstart.sh b/tools/testing/selftests/rcutorture/bin/jitterstart.sh
new file mode 100644
index 000000000000..3d710ad291c3
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/bin/jitterstart.sh
@@ -0,0 +1,37 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Start up the specified number of jitter.sh scripts in the background.
+#
+# Usage: . jitterstart.sh n jittering-dir duration [ sleepmax [ spinmax ] ]
+#
+# n: Number of jitter.sh scripts to start up.
+# jittering-dir: Directory in which to put "jittering" file.
+# duration: Time to run in seconds.
+# sleepmax: Maximum microseconds to sleep, defaults to one second.
+# spinmax: Maximum microseconds to spin, defaults to one millisecond.
+#
+# Copyright (C) 2021 Facebook, Inc.
+#
+# Authors: Paul E. McKenney <paulmck@kernel.org>
+
+jitter_n=$1
+if test -z "$jitter_n"
+then
+	echo jitterstart.sh: Missing count of jitter.sh scripts to start.
+	exit 33
+fi
+jittering_dir=$2
+if test -z "$jittering_dir"
+then
+	echo jitterstart.sh: Missing directory in which to place jittering file.
+	exit 34
+fi
+shift
+shift
+
+touch ${jittering_dir}/jittering
+for ((jitter_i = 1; jitter_i <= $jitter_n; jitter_i++))
+do
+	jitter.sh $jitter_i "${jittering_dir}/jittering" "$@" &
+done
diff --git a/tools/testing/selftests/rcutorture/bin/jitterstop.sh b/tools/testing/selftests/rcutorture/bin/jitterstop.sh
new file mode 100644
index 000000000000..576a4cf4b79a
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/bin/jitterstop.sh
@@ -0,0 +1,23 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Remove the "jittering" file, signaling the jitter.sh scripts to stop,
+# then wait for them to terminate.
+#
+# Usage: . jitterstop.sh jittering-dir
+#
+# jittering-dir: Directory containing "jittering" file.
+#
+# Copyright (C) 2021 Facebook, Inc.
+#
+# Authors: Paul E. McKenney <paulmck@kernel.org>
+
+jittering_dir=$1
+if test -z "$jittering_dir"
+then
+	echo jitterstop.sh: Missing directory in which to place jittering file.
+	exit 34
+fi
+
+rm -f ${jittering_dir}/jittering
+wait
diff --git a/tools/testing/selftests/rcutorture/bin/kvm.sh b/tools/testing/selftests/rcutorture/bin/kvm.sh
index a2ee3f2fff3c..d6973e4a2ecf 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm.sh
@@ -502,15 +502,12 @@ function dump(first, pastlast, batchnum)
 	print "if test -n \"$needqemurun\""
 	print "then"
 	print "\techo ---- Starting kernels. `date` | tee -a " rd "log";
-	print "\ttouch " rd "jittering"
-	for (j = 0; j < njitter; j++)
-		print "\tjitter.sh " j " " rd "jittering " dur " " ja[2] " " ja[3] "&"
+	print "\t. jitterstart.sh " njitter " " rd " " dur " " ja[2] " " ja[3]
 	print "\twhile ls $runfiles > /dev/null 2>&1"
 	print "\tdo"
 	print "\t\t:"
 	print "\tdone"
-	print "\trm -f " rd "jittering"
-	print "\twait"
+	print "\t. jitterstop.sh " rd
 	print "\techo ---- All kernel runs complete. `date` | tee -a " rd "log";
 	print "else"
 	print "\twait"