selftests: Fix runner.sh for non-bash shells

Commit 2964f6b ("selftests: Use ktap helpers for runner.sh") added a
number of bashisms and updated the interpreter specified for the script to
be /bin/bash to reflect this. Unfortunately this does not actually achieve
anything in production since the main way runner.sh is invoked is from the
top level run_kselftest.sh which sources it rather than running it as a
separate script and specifies the shell as /bin/sh. This means that on
systems where /bin/sh is not bash (such as Debian where /bin/sh defaults to
being dash) we see failures:

./run_kselftest.sh: 195: ./kselftest/runner.sh: Syntax error: "(" unexpected (expecting "}")

These bashisms come from this part of the change:

  4. In runner.sh run_one(), get the return value and use ktap helpers for
     all pass/fail reporting. This allows counting pass/fail numbers in the
     main process.

which uses a bash array to track all the subtests being run. Convert this
to use a simple flat variable instead.

Link: https://lore.kernel.org/r/[email protected]
Fixes: 2964f6b ("selftests: Use ktap helpers for runner.sh")
Signed-off-by: Mark Brown <[email protected]>
Signed-off-by: Shuah Khan <[email protected]>

Author: broonie

tools/testing/selftests/kselftest/runner.sh

@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/bin/sh
 # SPDX-License-Identifier: GPL-2.0
 #
 # Runs a set of tests in a given subdirectory.
@@ -193,7 +193,7 @@ run_many()
 	DIR="${PWD#${BASE_DIR}/}"
 	test_num=0
 	local rc
-	pids=()
+	pids=
 
 	for TEST in "$@"; do
 		BASENAME_TEST=$(basename $TEST)
@@ -204,15 +204,15 @@ run_many()
 		fi
 		if [ -n "$RUN_IN_NETNS" ]; then
 			run_in_netns &
-			pids+=($!)
+			pids="$pids $!"
 		else
 			run_one "$DIR" "$TEST" "$test_num"
 		fi
 	done
 
 	# These variables are outputs of ktap_helpers.sh but since we've
 	# run the test in a subprocess we need to update them manually
-	for pid in "${pids[@]}"; do
+	for pid in $pids; do
 		wait "$pid"
 		rc=$?
 		case "$rc" in