ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

9 files changed, 1128 insertions, 0 deletions

diff --git a/tools/testing/selftests/cpufreq/.gitignore b/tools/testing/selftests/cpufreq/.gitignore
new file mode 100644
index 000000000..67604e91e
--- /dev/null
+++ b/tools/testing/selftests/cpufreq/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+cpufreq_selftest.*
diff --git a/tools/testing/selftests/cpufreq/Makefile b/tools/testing/selftests/cpufreq/Makefile
new file mode 100644
index 000000000..9b2ccb10b
--- /dev/null
+++ b/tools/testing/selftests/cpufreq/Makefile
@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: GPL-2.0
+all:
+
+TEST_PROGS := main.sh
+TEST_FILES := cpu.sh cpufreq.sh governor.sh module.sh special-tests.sh
+EXTRA_CLEAN := cpufreq_selftest.dmesg_cpufreq.txt cpufreq_selftest.dmesg_full.txt cpufreq_selftest.txt
+
+include ../lib.mk
+
+clean:
diff --git a/tools/testing/selftests/cpufreq/config b/tools/testing/selftests/cpufreq/config
new file mode 100644
index 000000000..ce5068f5a
--- /dev/null
+++ b/tools/testing/selftests/cpufreq/config
@@ -0,0 +1,7 @@
+CONFIG_CPU_FREQ=y
+CONFIG_CPU_FREQ_STAT=y
+CONFIG_CPU_FREQ_GOV_POWERSAVE=y
+CONFIG_CPU_FREQ_GOV_USERSPACE=y
+CONFIG_CPU_FREQ_GOV_ONDEMAND=y
+CONFIG_CPU_FREQ_GOV_CONSERVATIVE=y
+CONFIG_CPU_FREQ_GOV_SCHEDUTIL=y
diff --git a/tools/testing/selftests/cpufreq/cpu.sh b/tools/testing/selftests/cpufreq/cpu.sh
new file mode 100755
index 000000000..39fdcdfb8
--- /dev/null
+++ b/tools/testing/selftests/cpufreq/cpu.sh
@@ -0,0 +1,85 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# CPU helpers
+
+# protect against multiple inclusion
+if [ $FILE_CPU ]; then
+	return 0
+else
+	FILE_CPU=DONE
+fi
+
+source cpufreq.sh
+
+for_each_cpu()
+{
+	cpus=$(ls $CPUROOT | grep "cpu[0-9].*")
+	for cpu in $cpus; do
+		$@ $cpu
+	done
+}
+
+for_each_non_boot_cpu()
+{
+	cpus=$(ls $CPUROOT | grep "cpu[1-9].*")
+	for cpu in $cpus; do
+		$@ $cpu
+	done
+}
+
+#$1: cpu
+offline_cpu()
+{
+	printf "Offline $1\n"
+	echo 0 > $CPUROOT/$1/online
+}
+
+#$1: cpu
+online_cpu()
+{
+	printf "Online $1\n"
+	echo 1 > $CPUROOT/$1/online
+}
+
+#$1: cpu
+reboot_cpu()
+{
+	offline_cpu $1
+	online_cpu $1
+}
+
+# Reboot CPUs
+# param: number of times we want to run the loop
+reboot_cpus()
+{
+	printf "** Test: Running ${FUNCNAME[0]} for $1 loops **\n\n"
+
+	for i in `seq 1 $1`; do
+		for_each_non_boot_cpu offline_cpu
+		for_each_non_boot_cpu online_cpu
+		printf "\n"
+	done
+
+	printf "\n%s\n\n" "------------------------------------------------"
+}
+
+# Prints warning for all CPUs with missing cpufreq directory
+print_unmanaged_cpus()
+{
+	for_each_cpu cpu_should_have_cpufreq_directory
+}
+
+# Counts CPUs with cpufreq directories
+count_cpufreq_managed_cpus()
+{
+	count=0;
+
+	for cpu in `ls $CPUROOT | grep "cpu[0-9].*"`; do
+		if [ -d $CPUROOT/$cpu/cpufreq ]; then
+			let count=count+1;
+		fi
+	done
+
+	echo $count;
+}
diff --git a/tools/testing/selftests/cpufreq/cpufreq.sh b/tools/testing/selftests/cpufreq/cpufreq.sh
new file mode 100755
index 000000000..9927b654f
--- /dev/null
+++ b/tools/testing/selftests/cpufreq/cpufreq.sh
@@ -0,0 +1,264 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+# protect against multiple inclusion
+if [ $FILE_CPUFREQ ]; then
+	return 0
+else
+	FILE_CPUFREQ=DONE
+fi
+
+source cpu.sh
+
+
+# $1: cpu
+cpu_should_have_cpufreq_directory()
+{
+	if [ ! -d $CPUROOT/$1/cpufreq ]; then
+		printf "Warning: No cpufreq directory present for $1\n"
+	fi
+}
+
+cpu_should_not_have_cpufreq_directory()
+{
+	if [ -d $CPUROOT/$1/cpufreq ]; then
+		printf "Warning: cpufreq directory present for $1\n"
+	fi
+}
+
+for_each_policy()
+{
+	policies=$(ls $CPUFREQROOT| grep "policy[0-9].*")
+	for policy in $policies; do
+		$@ $policy
+	done
+}
+
+for_each_policy_concurrent()
+{
+	policies=$(ls $CPUFREQROOT| grep "policy[0-9].*")
+	for policy in $policies; do
+		$@ $policy &
+	done
+}
+
+# $1: Path
+read_cpufreq_files_in_dir()
+{
+	local files=`ls $1`
+
+	printf "Printing directory: $1\n\n"
+
+	for file in $files; do
+		if [ -f $1/$file ]; then
+			printf "$file:"
+			#file is readable ?
+			local rfile=$(ls -l $1/$file | awk '$1 ~ /^.*r.*/ { print $NF; }')
+
+			if [ ! -z $rfile ]; then
+				cat $1/$file
+			else
+				printf "$file is not readable\n"
+			fi
+		else
+			printf "\n"
+			read_cpufreq_files_in_dir "$1/$file"
+		fi
+	done
+	printf "\n"
+}
+
+
+read_all_cpufreq_files()
+{
+	printf "** Test: Running ${FUNCNAME[0]} **\n\n"
+
+	read_cpufreq_files_in_dir $CPUFREQROOT
+
+	printf "%s\n\n" "------------------------------------------------"
+}
+
+
+# UPDATE CPUFREQ FILES
+
+# $1: directory path
+update_cpufreq_files_in_dir()
+{
+	local files=`ls $1`
+
+	printf "Updating directory: $1\n\n"
+
+	for file in $files; do
+		if [ -f $1/$file ]; then
+			# file is readable and writable ?
+			local rwfile=$(ls -l $1/$file | awk '$1 ~ /^.*rw.*/ { print $NF; }')
+
+			if [ ! -z $rwfile ]; then
+				# scaling_setspeed is a special file and we
+				# should skip updating it
+				if [ $file != "scaling_setspeed" ]; then
+					local val=$(cat $1/$file)
+					printf "Writing $val to: $file\n"
+					echo $val > $1/$file
+				fi
+			fi
+		else
+			printf "\n"
+			update_cpufreq_files_in_dir "$1/$file"
+		fi
+	done
+
+	printf "\n"
+}
+
+# Update all writable files with their existing values
+update_all_cpufreq_files()
+{
+	printf "** Test: Running ${FUNCNAME[0]} **\n\n"
+
+	update_cpufreq_files_in_dir $CPUFREQROOT
+
+	printf "%s\n\n" "------------------------------------------------"
+}
+
+
+# CHANGE CPU FREQUENCIES
+
+# $1: policy
+find_current_freq()
+{
+	cat $CPUFREQROOT/$1/scaling_cur_freq
+}
+
+# $1: policy
+# $2: frequency
+set_cpu_frequency()
+{
+	printf "Change frequency for $1 to $2\n"
+	echo $2 > $CPUFREQROOT/$1/scaling_setspeed
+}
+
+# $1: policy
+test_all_frequencies()
+{
+	local filepath="$CPUFREQROOT/$1"
+
+	backup_governor $1
+
+	local found=$(switch_governor $1 "userspace")
+	if [ $found = 1 ]; then
+		printf "${FUNCNAME[0]}: userspace governor not available for: $1\n"
+		return;
+	fi
+
+	printf "Switched governor for $1 to userspace\n\n"
+
+	local freqs=$(cat $filepath/scaling_available_frequencies)
+	printf "Available frequencies for $1: $freqs\n\n"
+
+	# Set all frequencies one-by-one
+	for freq in $freqs; do
+		set_cpu_frequency $1 $freq
+	done
+
+	printf "\n"
+
+	restore_governor $1
+}
+
+# $1: loop count
+shuffle_frequency_for_all_cpus()
+{
+	printf "** Test: Running ${FUNCNAME[0]} for $1 loops **\n\n"
+
+	for i in `seq 1 $1`; do
+		for_each_policy test_all_frequencies
+	done
+	printf "\n%s\n\n" "------------------------------------------------"
+}
+
+# Basic cpufreq tests
+cpufreq_basic_tests()
+{
+	printf "*** RUNNING CPUFREQ SANITY TESTS ***\n"
+	printf "====================================\n\n"
+
+	count=$(count_cpufreq_managed_cpus)
+	if [ $count = 0 ]; then
+		ktap_exit_fail_msg "No cpu is managed by cpufreq core, exiting\n"
+	else
+		printf "CPUFreq manages: $count CPUs\n\n"
+	fi
+
+	# Detect & print which CPUs are not managed by cpufreq
+	print_unmanaged_cpus
+
+	# read/update all cpufreq files
+	read_all_cpufreq_files
+	update_all_cpufreq_files
+
+	# hotplug cpus
+	reboot_cpus 5
+
+	# Test all frequencies
+	shuffle_frequency_for_all_cpus 2
+
+	# Test all governors
+	shuffle_governors_for_all_cpus 1
+}
+
+# Suspend/resume
+# $1: "suspend" or "hibernate", $2: loop count
+do_suspend()
+{
+	printf "** Test: Running ${FUNCNAME[0]}: Trying $1 for $2 loops **\n\n"
+
+	# Is the directory available
+	if [ ! -d $SYSFS/power/ -o ! -f $SYSFS/power/state ]; then
+		printf "$SYSFS/power/state not available\n"
+		return 1
+	fi
+
+	if [ $1 = "suspend" ]; then
+		filename="mem"
+	elif [ $1 = "hibernate" ]; then
+		filename="disk"
+	else
+		printf "$1 is not a valid option\n"
+		return 1
+	fi
+
+	if [ -n $filename ]; then
+		present=$(cat $SYSFS/power/state | grep $filename)
+
+		if [ -z "$present" ]; then
+			printf "Tried to $1 but $filename isn't present in $SYSFS/power/state\n"
+			return 1;
+		fi
+
+		for i in `seq 1 $2`; do
+			printf "Starting $1\n"
+
+			if [ "$3" = "rtc" ]; then
+				if ! command -v rtcwake &> /dev/null; then
+					printf "rtcwake could not be found, please install it.\n"
+					return 1
+				fi
+
+				rtcwake -m $filename -s 15
+
+				if [ $? -ne 0 ]; then
+					printf "Failed to suspend using RTC wake alarm\n"
+					return 1
+				fi
+			else
+				echo $filename > $SYSFS/power/state
+			fi
+
+			printf "Came out of $1\n"
+
+			printf "Do basic tests after finishing $1 to verify cpufreq state\n\n"
+			cpufreq_basic_tests
+		done
+	fi
+}
diff --git a/tools/testing/selftests/cpufreq/governor.sh b/tools/testing/selftests/cpufreq/governor.sh
new file mode 100755
index 000000000..cf59e63f8
--- /dev/null
+++ b/tools/testing/selftests/cpufreq/governor.sh
@@ -0,0 +1,170 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Test governors
+
+# protect against multiple inclusion
+if [ $FILE_GOVERNOR ]; then
+	return 0
+else
+	FILE_GOVERNOR=DONE
+fi
+
+source cpu.sh
+source cpufreq.sh
+
+CUR_GOV=
+CUR_FREQ=
+
+# Per-policy backup, keyed by policy so multiple policies can be saved at once
+# (backup_governor/restore_governor also keep CUR_GOV/CUR_FREQ for callers that
+# read them directly).
+declare -A SAVED_GOVERNORS
+declare -A SAVED_FREQS
+
+# Find governor's directory path
+# $1: policy, $2: governor
+find_gov_directory()
+{
+	if [ -d $CPUFREQROOT/$2 ]; then
+		printf "$CPUFREQROOT/$2\n"
+	elif [ -d $CPUFREQROOT/$1/$2 ]; then
+		printf "$CPUFREQROOT/$1/$2\n"
+	else
+		printf "INVALID\n"
+	fi
+}
+
+# $1: policy
+find_current_governor()
+{
+	cat $CPUFREQROOT/$1/scaling_governor
+}
+
+# $1: policy
+backup_governor()
+{
+	CUR_GOV=$(find_current_governor $1)
+	SAVED_GOVERNORS[$1]=$CUR_GOV
+
+	printf "Governor backup done for $1: $CUR_GOV\n"
+
+	if [ $CUR_GOV == "userspace" ]; then
+		CUR_FREQ=$(find_current_freq $1)
+		SAVED_FREQS[$1]=$CUR_FREQ
+		printf "Governor frequency backup done for $1: $CUR_FREQ\n"
+	fi
+
+	printf "\n"
+}
+
+# $1: policy
+restore_governor()
+{
+	CUR_GOV=${SAVED_GOVERNORS[$1]}
+	__switch_governor $1 $CUR_GOV
+
+	printf "Governor restored for $1 to $CUR_GOV\n"
+
+	if [ $CUR_GOV == "userspace" ]; then
+		CUR_FREQ=${SAVED_FREQS[$1]}
+		set_cpu_frequency $1 $CUR_FREQ
+		printf "Governor frequency restored for $1: $CUR_FREQ\n"
+	fi
+
+	printf "\n"
+}
+
+# Save/restore governors for every policy at once
+save_all_governors()
+{
+	for_each_policy backup_governor
+}
+
+restore_all_governors()
+{
+	for_each_policy restore_governor
+}
+
+# param:
+# $1: policy, $2: governor
+__switch_governor()
+{
+	echo $2 > $CPUFREQROOT/$1/scaling_governor
+}
+
+# param:
+# $1: cpu, $2: governor
+__switch_governor_for_cpu()
+{
+	echo $2 > $CPUROOT/$1/cpufreq/scaling_governor
+}
+
+# SWITCH GOVERNORS
+
+# $1: cpu, $2: governor
+switch_governor()
+{
+	local filepath=$CPUFREQROOT/$1/scaling_available_governors
+
+	# check if governor is available
+	local found=$(cat $filepath | grep $2 | wc -l)
+	if [ $found = 0 ]; then
+		echo 1;
+		return
+	fi
+
+	__switch_governor $1 $2
+	echo 0;
+}
+
+# $1: policy, $2: governor
+switch_show_governor()
+{
+	# switch governor
+	__switch_governor $1 $2
+
+	printf "\nSwitched governor for $1 to $2\n\n"
+
+	if [ $2 == "userspace" -o $2 == "powersave" -o $2 == "performance" ]; then
+		printf "No files to read for $2 governor\n\n"
+		return
+	fi
+
+	# show governor files
+	local govpath=$(find_gov_directory $1 $2)
+	read_cpufreq_files_in_dir $govpath
+}
+
+# $1: function to be called, $2: policy
+call_for_each_governor()
+{
+	local filepath=$CPUFREQROOT/$2/scaling_available_governors
+
+	# Exit if cpu isn't managed by cpufreq core
+	if [ ! -f $filepath ]; then
+		return;
+	fi
+
+	backup_governor $2
+
+	local governors=$(cat $filepath)
+	printf "Available governors for $2: $governors\n"
+
+	for governor in $governors; do
+		$1 $2 $governor
+	done
+
+	restore_governor $2
+}
+
+# $1: loop count
+shuffle_governors_for_all_cpus()
+{
+	printf "** Test: Running ${FUNCNAME[0]} for $1 loops **\n\n"
+
+	for i in `seq 1 $1`; do
+		for_each_policy call_for_each_governor switch_show_governor
+	done
+	printf "%s\n\n" "------------------------------------------------"
+}
diff --git a/tools/testing/selftests/cpufreq/main.sh b/tools/testing/selftests/cpufreq/main.sh
new file mode 100755
index 000000000..f12ff7416
--- /dev/null
+++ b/tools/testing/selftests/cpufreq/main.sh
@@ -0,0 +1,218 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+source cpu.sh
+source cpufreq.sh
+source governor.sh
+source module.sh
+source special-tests.sh
+
+DIR="$(dirname $(readlink -f "$0"))"
+source "${DIR}"/../kselftest/ktap_helpers.sh
+
+FUNC=basic	# do basic tests by default
+OUTFILE=cpufreq_selftest
+SYSFS=
+CPUROOT=
+CPUFREQROOT=
+
+helpme()
+{
+	printf "Usage: $0 [-h] [-todg args]
+	[-h <help>]
+	[-o <output-file-for-dump>]
+	[-t <basic: Basic cpufreq testing
+	     suspend: suspend/resume,
+	     hibernate: hibernate/resume,
+	     suspend_rtc: suspend/resume back using the RTC wakeup alarm,
+	     hibernate_rtc: hibernate/resume back using the RTC wakeup alarm,
+	     modtest: test driver or governor modules. Only to be used with -d or -g options,
+	     sptest1: Simple governor switch to produce lockdep.
+	     sptest2: Concurrent governor switch to produce lockdep.
+	     sptest3: Governor races, shuffle between governors quickly.
+	     sptest4: CPU hotplugs with updates to cpufreq files.>]
+	[-d <driver's module name: only with \"-t modtest>\"]
+	[-g <governor's module name: only with \"-t modtest>\"]
+	\n"
+	exit "${KSFT_FAIL}"
+}
+
+prerequisite()
+{
+	msg="skip all tests:"
+
+	if [ $UID != 0 ]; then
+		ktap_skip_all "$msg must be run as root"
+		exit "${KSFT_SKIP}"
+	fi
+
+	taskset -p 01 $$
+
+	SYSFS=`mount -t sysfs | head -1 | awk '{ print $3 }'`
+
+	if [ ! -d "$SYSFS" ]; then
+		ktap_skip_all "$msg sysfs is not mounted"
+		exit "${KSFT_SKIP}"
+	fi
+
+	CPUROOT=$SYSFS/devices/system/cpu
+	CPUFREQROOT="$CPUROOT/cpufreq"
+
+	if ! ls $CPUROOT/cpu* > /dev/null 2>&1; then
+		ktap_skip_all "$msg cpus not available in sysfs"
+		exit "${KSFT_SKIP}"
+	fi
+
+	if ! ls $CPUROOT/cpufreq > /dev/null 2>&1; then
+		ktap_skip_all "$msg cpufreq directory not available in sysfs"
+		exit "${KSFT_SKIP}"
+	fi
+}
+
+parse_arguments()
+{
+	while getopts ht:o:d:g: arg
+	do
+		case $arg in
+			h) # --help
+				helpme
+				;;
+
+			t) # --func_type (Function to perform: basic, suspend, hibernate,
+			   # suspend_rtc, hibernate_rtc, modtest, sptest1/2/3/4 (default: basic))
+				FUNC=$OPTARG
+				;;
+
+			o) # --output-file (Output file to store dumps)
+				OUTFILE=$OPTARG
+				;;
+
+			d) # --driver-mod-name (Name of the driver module)
+				DRIVER_MOD=$OPTARG
+				;;
+
+			g) # --governor-mod-name (Name of the governor module)
+				GOVERNOR_MOD=$OPTARG
+				;;
+
+			\?)
+				helpme
+				;;
+		esac
+	done
+}
+
+do_test()
+{
+	# Check if CPUs are managed by cpufreq or not
+	count=$(count_cpufreq_managed_cpus)
+
+	if [ $count = 0 -a $FUNC != "modtest" ]; then
+		ktap_exit_fail_msg "No cpu is managed by cpufreq core, exiting"
+	fi
+
+	case "$FUNC" in
+		"basic")
+		cpufreq_basic_tests
+		;;
+
+		"suspend")
+		do_suspend "suspend" 1
+		;;
+
+		"hibernate")
+		do_suspend "hibernate" 1
+		;;
+
+		"suspend_rtc")
+                do_suspend "suspend" 1 rtc
+                ;;
+
+                "hibernate_rtc")
+                do_suspend "hibernate" 1 rtc
+                ;;
+
+		"modtest")
+		# Do we have modules in place?
+		if [ -z $DRIVER_MOD ] && [ -z $GOVERNOR_MOD ]; then
+			ktap_exit_fail_msg "No driver or governor module passed with -d or -g"
+		fi
+
+		if [ $DRIVER_MOD ]; then
+			if [ $GOVERNOR_MOD ]; then
+				module_test $DRIVER_MOD $GOVERNOR_MOD
+			else
+				module_driver_test $DRIVER_MOD
+			fi
+		else
+			if [ $count = 0 ]; then
+				ktap_exit_fail_msg "No cpu is managed by cpufreq core, exiting"
+			fi
+
+			module_governor_test $GOVERNOR_MOD
+		fi
+		;;
+
+		"sptest1")
+		simple_lockdep
+		;;
+
+		"sptest2")
+		concurrent_lockdep
+		;;
+
+		"sptest3")
+		governor_race
+		;;
+
+		"sptest4")
+		hotplug_with_updates
+		;;
+
+		*)
+		ktap_print_msg "Invalid [-f] function type"
+		helpme
+		;;
+	esac
+}
+
+# clear dumps
+# $1: file name
+clear_dumps()
+{
+	echo "" > $1.txt
+	echo "" > $1.dmesg_cpufreq.txt
+	echo "" > $1.dmesg_full.txt
+}
+
+# $1: output file name
+dmesg_dumps()
+{
+	dmesg | grep cpufreq >> $1.dmesg_cpufreq.txt
+
+	# We may need the full logs as well
+	dmesg >> $1.dmesg_full.txt
+}
+
+ktap_print_header
+
+# Parse arguments
+parse_arguments $@
+
+ktap_set_plan 1
+
+# Make sure all requirements are met
+prerequisite
+
+# Run requested functions
+clear_dumps $OUTFILE
+do_test | tee -a $OUTFILE.txt
+if [ "${PIPESTATUS[0]}" -ne 0 ]; then
+    exit ${PIPESTATUS[0]};
+fi
+dmesg_dumps $OUTFILE
+
+ktap_test_pass "Completed successfully"
+
+ktap_print_totals
+exit "${KSFT_PASS}"
diff --git a/tools/testing/selftests/cpufreq/module.sh b/tools/testing/selftests/cpufreq/module.sh
new file mode 100755
index 000000000..7f2667e0a
--- /dev/null
+++ b/tools/testing/selftests/cpufreq/module.sh
@@ -0,0 +1,242 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Modules specific tests cases
+
+# protect against multiple inclusion
+if [ $FILE_MODULE ]; then
+	return 0
+else
+	FILE_MODULE=DONE
+fi
+
+source cpu.sh
+source cpufreq.sh
+source governor.sh
+
+# Check basic insmod/rmmod
+# $1: module
+test_basic_insmod_rmmod()
+{
+	printf "** Test: Running ${FUNCNAME[0]} **\n\n"
+
+	printf "Inserting $1 module\n"
+	# insert module
+	insmod $1
+	if [ $? != 0 ]; then
+		ktap_exit_fail_msg "Insmod $1 failed\n"
+	fi
+
+	printf "Removing $1 module\n"
+	# remove module
+	rmmod $1
+	if [ $? != 0 ]; then
+		ktap_exit_fail_msg "rmmod $1 failed\n"
+	fi
+
+	printf "\n"
+}
+
+# Insert cpufreq driver module and perform basic tests
+# $1: cpufreq-driver module to insert
+# $2: If we want to play with CPUs (1) or not (0)
+module_driver_test_single()
+{
+	printf "** Test: Running ${FUNCNAME[0]} for driver $1 and cpus_hotplug=$2 **\n\n"
+
+	if [ $2 -eq 1 ]; then
+		# offline all non-boot CPUs
+		for_each_non_boot_cpu offline_cpu
+		printf "\n"
+	fi
+
+	# insert module
+	printf "Inserting $1 module\n\n"
+	insmod $1
+	if [ $? != 0 ]; then
+		printf "Insmod $1 failed\n"
+		return;
+	fi
+
+	if [ $2 -eq 1 ]; then
+		# online all non-boot CPUs
+		for_each_non_boot_cpu online_cpu
+		printf "\n"
+	fi
+
+	# run basic tests
+	cpufreq_basic_tests
+
+	# remove module
+	printf "Removing $1 module\n\n"
+	rmmod $1
+	if [ $? != 0 ]; then
+		printf "rmmod $1 failed\n"
+		return;
+	fi
+
+	# There shouldn't be any cpufreq directories now.
+	for_each_cpu cpu_should_not_have_cpufreq_directory
+	printf "\n"
+}
+
+# $1: cpufreq-driver module to insert
+module_driver_test()
+{
+	printf "** Test: Running ${FUNCNAME[0]} **\n\n"
+
+	# check if module is present or not
+	ls $1 > /dev/null
+	if [ $? != 0 ]; then
+		printf "$1: not present in `pwd` folder\n"
+		return;
+	fi
+
+	# test basic module tests
+	test_basic_insmod_rmmod $1
+
+	# Do simple module test
+	module_driver_test_single $1 0
+
+	# Remove CPUs before inserting module and then bring them back
+	module_driver_test_single $1 1
+	printf "\n"
+}
+
+# find governor name based on governor module name
+# $1: governor module name
+find_gov_name()
+{
+	if [ $1 = "cpufreq_ondemand.ko" ]; then
+		printf "ondemand"
+	elif [ $1 = "cpufreq_conservative.ko" ]; then
+		printf "conservative"
+	elif [ $1 = "cpufreq_userspace.ko" ]; then
+		printf "userspace"
+	elif [ $1 = "cpufreq_performance.ko" ]; then
+		printf "performance"
+	elif [ $1 = "cpufreq_powersave.ko" ]; then
+		printf "powersave"
+	elif [ $1 = "cpufreq_schedutil.ko" ]; then
+		printf "schedutil"
+	fi
+}
+
+# $1: governor string, $2: governor module, $3: policy
+# example: module_governor_test_single "ondemand" "cpufreq_ondemand.ko" 2
+module_governor_test_single()
+{
+	printf "** Test: Running ${FUNCNAME[0]} for $3 **\n\n"
+
+	backup_governor $3
+
+	# switch to new governor
+	printf "Switch from $CUR_GOV to $1\n"
+	switch_show_governor $3 $1
+
+	# try removing module, it should fail as governor is used
+	printf "Removing $2 module\n\n"
+	rmmod $2
+	if [ $? = 0 ]; then
+		printf "WARN: rmmod $2 succeeded even if governor is used\n"
+		insmod $2
+	else
+		printf "Pass: unable to remove $2 while it is being used\n\n"
+	fi
+
+	# switch back to old governor
+	printf "Switchback to $CUR_GOV from $1\n"
+	restore_governor $3
+	printf "\n"
+}
+
+# Insert cpufreq governor module and perform basic tests
+# $1: cpufreq-governor module to insert
+module_governor_test()
+{
+	printf "** Test: Running ${FUNCNAME[0]} **\n\n"
+
+	# check if module is present or not
+	ls $1 > /dev/null
+	if [ $? != 0 ]; then
+		printf "$1: not present in `pwd` folder\n"
+		return;
+	fi
+
+	# test basic module tests
+	test_basic_insmod_rmmod $1
+
+	# insert module
+	printf "Inserting $1 module\n\n"
+	insmod $1
+	if [ $? != 0 ]; then
+		printf "Insmod $1 failed\n"
+		return;
+	fi
+
+	# switch to new governor for each cpu
+	for_each_policy module_governor_test_single $(find_gov_name $1) $1
+
+	# remove module
+	printf "Removing $1 module\n\n"
+	rmmod $1
+	if [ $? != 0 ]; then
+		printf "rmmod $1 failed\n"
+		return;
+	fi
+	printf "\n"
+}
+
+# test modules: driver and governor
+# $1: driver module, $2: governor module
+module_test()
+{
+	printf "** Test: Running ${FUNCNAME[0]} **\n\n"
+
+	# check if modules are present or not
+	ls $1 $2 > /dev/null
+	if [ $? != 0 ]; then
+		printf "$1 or $2: is not present in `pwd` folder\n"
+		return;
+	fi
+
+	# TEST1: Insert gov after driver
+	# insert driver module
+	printf "Inserting $1 module\n\n"
+	insmod $1
+	if [ $? != 0 ]; then
+		printf "Insmod $1 failed\n"
+		return;
+	fi
+
+	# run governor tests
+	module_governor_test $2
+
+	# remove driver module
+	printf "Removing $1 module\n\n"
+	rmmod $1
+	if [ $? != 0 ]; then
+		printf "rmmod $1 failed\n"
+		return;
+	fi
+
+	# TEST2: Insert driver after governor
+	# insert governor module
+	printf "Inserting $2 module\n\n"
+	insmod $2
+	if [ $? != 0 ]; then
+		printf "Insmod $2 failed\n"
+		return;
+	fi
+
+	# run governor tests
+	module_driver_test $1
+
+	# remove driver module
+	printf "Removing $2 module\n\n"
+	rmmod $2
+	if [ $? != 0 ]; then
+		printf "rmmod $2 failed\n"
+		return;
+	fi
+}
diff --git a/tools/testing/selftests/cpufreq/special-tests.sh b/tools/testing/selftests/cpufreq/special-tests.sh
new file mode 100755
index 000000000..e87ed7c8e
--- /dev/null
+++ b/tools/testing/selftests/cpufreq/special-tests.sh
@@ -0,0 +1,130 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+#
+# Special test cases reported by people
+
+# Testcase 1: Reported here: http://marc.info/?l=linux-pm&m=140618592709858&w=2
+
+# protect against multiple inclusion
+if [ $FILE_SPECIAL ]; then
+	return 0
+else
+	FILE_SPECIAL=DONE
+fi
+
+source cpu.sh
+source cpufreq.sh
+source governor.sh
+
+# Test 1
+# $1: policy
+__simple_lockdep()
+{
+	# switch to ondemand
+	__switch_governor $1 "ondemand"
+
+	# cat ondemand files
+	local ondir=$(find_gov_directory $1 "ondemand")
+	if [ -z $ondir ]; then
+		printf "${FUNCNAME[0]}Ondemand directory not created, quit"
+		return
+	fi
+
+	cat $ondir/*
+
+	# switch to conservative
+	__switch_governor $1 "conservative"
+}
+
+simple_lockdep()
+{
+	printf "** Test: Running ${FUNCNAME[0]} **\n"
+
+	save_all_governors
+	for_each_policy __simple_lockdep
+	restore_all_governors
+}
+
+# Test 2
+# $1: policy
+__concurrent_lockdep()
+{
+	for i in `seq 0 100`; do
+		__simple_lockdep $1
+	done
+}
+
+concurrent_lockdep()
+{
+	printf "** Test: Running ${FUNCNAME[0]} **\n"
+
+	save_all_governors
+	for_each_policy_concurrent __concurrent_lockdep
+	wait
+	restore_all_governors
+}
+
+# Test 3
+quick_shuffle()
+{
+	# this is called concurrently from governor_race
+	for I in `seq 1000`
+	do
+		echo ondemand | tee $CPUFREQROOT/policy*/scaling_governor &
+		echo userspace | tee $CPUFREQROOT/policy*/scaling_governor &
+	done
+	wait
+}
+
+governor_race()
+{
+	printf "** Test: Running ${FUNCNAME[0]} **\n"
+
+	save_all_governors
+
+	# run 8 concurrent instances
+	for I in `seq 8`
+	do
+		quick_shuffle &
+	done
+	wait
+
+	restore_all_governors
+}
+
+# Test 4
+# $1: cpu
+hotplug_with_updates_cpu()
+{
+	local filepath="$CPUROOT/$1/cpufreq"
+
+	# switch to ondemand
+	__switch_governor_for_cpu $1 "ondemand"
+
+	for i in `seq 1 5000`
+	do
+		reboot_cpu $1
+	done &
+
+	local freqs=$(cat $filepath/scaling_available_frequencies)
+	local oldfreq=$(cat $filepath/scaling_min_freq)
+
+	for j in `seq 1 5000`
+	do
+		# Set all frequencies one-by-one
+		for freq in $freqs; do
+			echo $freq > $filepath/scaling_min_freq
+		done
+	done
+
+	# restore old freq
+	echo $oldfreq > $filepath/scaling_min_freq
+}
+
+hotplug_with_updates()
+{
+	save_all_governors
+	for_each_non_boot_cpu hotplug_with_updates_cpu
+	wait
+	restore_all_governors
+}