fuzz/llvm: add common.sh for llvm fuzzers

`common.sh` - add common function to start fuzzers in
parallel and quick sequential run

add `get_testn` - get number of test to run in parallel

Signed-off-by: Sebastian Brzezinka <sebastian.brzezinka@intel.com>
Change-Id: I7c70b5221887c29b495a1632545877ca7cca0945
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/16323
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>

test/fuzz/llvm/common.sh

@@ -0,0 +1,69 @@
+#!/usr/bin/env bash
+#  SPDX-License-Identifier: BSD-3-Clause
+#  Copyright (C) 2022 Intel Corporation
+#  All rights reserved.
+#
+
+# Store pids of parallel fuzzer tests
+pids=()
+
+function cleanup() {
+	rm -rf "$@"
+	# Make sure that there is no process left hanging
+	kill -9 "${pids[@]}" || :
+}
+
+function get_testn() {
+	local fuzz_num=$1
+	local mem_size=$2
+	local nproc
+	nproc=$(nproc)
+	# Choose lower value, best case scenario is one test per core
+	local testn=$((fuzz_num < nproc ? fuzz_num : nproc))
+
+	export HUGEMEM=$((mem_size * testn))
+	setup
+	TESTN=$testn
+}
+
+function start_llvm_fuzz_all() {
+	local testn=$1    # Number of test to run in parallel
+	local fuzz_num=$2 # Number of fuzzer tests
+	local time=$3     # Time available for all fuzzers
+	local core
+
+	# Calculate time for a single test and multiply it by number
+	# of test execute in parallel and round it up to 1 sek per test
+	timen=$(printf %d $(((time / fuzz_num) * testn)))
+	timen=$((timen == 0 ? 1 : timen))
+
+	for ((i = 0; i < fuzz_num; i++)); do
+		core=$(printf "0x%x" $((0x1 << (i % testn))))
+		start_llvm_fuzz $i $timen $core &> $output_dir/llvm/llvm_"$FUZZER"_$i.txt &
+		pids+=($!)
+
+		# Wait for processes to finish
+		if (((i + 1) % testn == 0 || fuzz_num - i - 1 == 0)); then
+			(
+				sleep $((timen * 10 + 100))
+				echo "Timeout $time"
+				exit 1
+			) &
+			timeout_pid=$!
+			for pid in "${pids[@]}"; do
+				wait $pid
+			done
+			kill $timeout_pid || :
+			pids=()
+		fi
+	done
+}
+
+function start_llvm_fuzz_short() {
+	local fuzz_num=$1
+	local time=$2
+
+	for ((i = 0; i < fuzz_num; i++)); do
+		start_llvm_fuzz $i $time 0x1
+	done
+}