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#!/usr/bin/bash
#
# Takes a list of modules and unloads them and all dependent modules.
# If a module cannot be unloaded (e.g. it's in use), an error is
# returned.
###############################################################################

SCRIPT_NAME="$(basename "$0")"
LCTL=${LCTL:-lctl}
if [[ -z "$DEBUG" ]]; then
	if [[ -n "$DEBUG_RMMOD" ]]; then
		DEBUG=true
	else
		DEBUG=false
	fi
fi

# Print help message
print_usage() {
	echo "$SCRIPT_NAME -h|--help"
	echo "$SCRIPT_NAME [-d|--debug-kernel] [modulesname...]"
	echo
	echo -e "\t-h, --help\t\tDisplay this help message"
	echo -e "\t-d, --debug-kernel\tDisplay lustre kernel debug messages"
	echo -e "\tmodulesname\t\tList of lustre modules to unload. By default"
	echo -e "\t\t\t\tldiskfs and libcfs (and their dependencies) are"
	echo -e "\t\t\t\tselected."
}

# Print kernel debug message for lustre modules
print_debug() {
	local debug_file

	$LCTL mark "$SCRIPT_NAME : Stop debug"
	if [[ $DEBUG_RMMOD == "-" ]]; then
		debug_file="" # dump to stdout
	elif [[ "${DEBUG_RMMOD:0:1}" == "/" ]]; then
		debug_file="$DEBUG_RMMOD"
	else
		debug_file=$TMP/${DEBUG_RMMOD:-debug}
	fi
	echo "Dump memory leak logs to $debug_file"
	$LCTL debug_kernel $debug_file
	DEBUG=false
}

# Unload all modules dependent on $1 (exclude removal of $1)
unload_dep_modules_exclusive() {
	local MODULE=$1

	local DEPS="$(lsmod | awk '($1 == "'$MODULE'") { print $4 }')"
	for SUBMOD in $(echo $DEPS | tr ',' ' '); do
		unload_dep_modules_inclusive $SUBMOD || return 1
	done
	return 0
}

# Unload all modules dependent on $1 (include removal of $1)
unload_dep_modules_inclusive() {
	local MODULE=$1

	# if $MODULE not loaded, return 0
	lsmod | grep -E -q "^\<$MODULE\>" || return 0
	unload_dep_modules_exclusive $MODULE || return 1

	if $DEBUG; then
		if [ "$MODULE" = 'libcfs' ]; then
			print_debug
		fi
		$LCTL mark "$SCRIPT_NAME : Unload $MODULE"
	fi

	rmmod $MODULE || return 1
	return 0
}

declare -a modules
while [ $# -gt 0 ]; do
	case "$1" in
		-h|--help)
			print_usage >&2
			exit 0
			;;
		-d|--debug-kernel)
			if lsmod | grep -E -q '^libcfs'; then
				DEBUG='true'
			else
				echo "Debug unavailable: libcfs is not loaded" >&2
			fi
			;;
		-*)
			echo "Error invalid option" >&2
			print_usage >&2
			exit 2
			;;
		*)
			modules+=("$1")
			;;
	esac
	shift
done

# To maintain backwards compatibility, ldiskfs and libcfs must be
# unloaded if no parameters are given, or if only the ldiskfs parameter
# is given. It's ugly, but is needed to emulate the prior functionality
if [ "${#modules[@]}" -eq 0 ] || [ "${modules[*]}" = "ldiskfs" ]; then
	unload_all=true
	modules=('lnet_selftest' 'ldiskfs' 'libcfs')
else
	unload_all=false
fi

export KMEMLEAK=${KMEMLEAK:-/sys/kernel/debug/kmemleak}
KMEMLEAK_MODS=/tmp/kmemleak-modules-list.txt
if [[ -w $KMEMLEAK ]]; then
	kmemleak_out=$(echo scan > $KMEMLEAK 2>&1 || true)

	if [[ "$kmemleak_out" =~ "Device or resource busy" ]]; then
		echo "kmemleak disabled"
		export KMEMLEAK=disabled
	else
		kmemleak_pre=/tmp/kmemleak-pre-unload.txt

		echo $kmemleak_out
		cat /proc/modules > $KMEMLEAK_MODS
		cat $KMEMLEAK > $kmemleak_pre
		[[ -s $kmemleak_pre ]] && logger -t leak-pre -f $kmemleak_pre
		rm -f $kmemleak_pre
		# Clear everything here so that only new leaks show up
		# after module unload
		echo clear > $KMEMLEAK
	fi
fi

# Manage debug
if $DEBUG; then
	echo "Lustre debug parameters:" >&2
	$LCTL get_param debug >&2
	$LCTL get_param debug_mb >&2

	$LCTL mark "$SCRIPT_NAME : Start debug"
fi

if $unload_all; then
	unload_dep_modules_inclusive 'ptlrpc' || exit 1
	# LNet may have an internal ref which can prevent LND modules from
	# unloading. Try to drop it before unloading modules.
	# NB: we squelch stderr because lnetctl/lctl may complain about
	# LNet being "busy", but this is normal. We're making a best effort
	# here.
	# Prefer lnetctl if it is present
	if [ -n "$(which lnetctl 2>/dev/null)" ]; then
		lnetctl lnet unconfigure 2>/dev/null
	elif [ -n "$(which lctl 2>/dev/null)" ]; then
		lctl net down 2>/dev/null | grep -v "LNET ready to unload"
	fi
fi

for mod in ${modules[*]}; do
	unload_dep_modules_inclusive $mod || exit 1
done

if $DEBUG; then
	print_debug
fi

if [[ -f $KMEMLEAK ]]; then
	kmemleak_post=/tmp/kmemleak-post-unload.txt

	echo scan > $KMEMLEAK 2>&1 | grep -v "Device or resource busy"
	cat $KMEMLEAK > $kmemleak_post
	[[ -s $kmemleak_post ]] && logger -t leak-mods -f $KMEMLEAK_MODS &&
		logger -t leak-post -f $kmemleak_post
	rm -f $kmemleak_post $KMEMLEAK_MODS
fi

exit 0