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>

1 files changed, 320 insertions, 0 deletions

diff --git a/tools/perf/perf-completion.sh b/tools/perf/perf-completion.sh
new file mode 100644
index 000000000..69cba3c17
--- /dev/null
+++ b/tools/perf/perf-completion.sh
@@ -0,0 +1,320 @@
+# perf bash and zsh completion
+# SPDX-License-Identifier: GPL-2.0
+
+# Taken from git.git's completion script.
+__my_reassemble_comp_words_by_ref()
+{
+	local exclude i j first
+	# Which word separators to exclude?
+	exclude="${1//[^$COMP_WORDBREAKS]}"
+	cword_=$COMP_CWORD
+	if [ -z "$exclude" ]; then
+		words_=("${COMP_WORDS[@]}")
+		return
+	fi
+	# List of word completion separators has shrunk;
+	# re-assemble words to complete.
+	for ((i=0, j=0; i < ${#COMP_WORDS[@]}; i++, j++)); do
+		# Append each nonempty word consisting of just
+		# word separator characters to the current word.
+		first=t
+		while
+			[ $i -gt 0 ] &&
+			[ -n "${COMP_WORDS[$i]}" ] &&
+			# word consists of excluded word separators
+			[ "${COMP_WORDS[$i]//[^$exclude]}" = "${COMP_WORDS[$i]}" ]
+		do
+			# Attach to the previous token,
+			# unless the previous token is the command name.
+			if [ $j -ge 2 ] && [ -n "$first" ]; then
+				((j--))
+			fi
+			first=
+			words_[$j]=${words_[j]}${COMP_WORDS[i]}
+			if [ $i = $COMP_CWORD ]; then
+				cword_=$j
+			fi
+			if (($i < ${#COMP_WORDS[@]} - 1)); then
+				((i++))
+			else
+				# Done.
+				return
+			fi
+		done
+		words_[$j]=${words_[j]}${COMP_WORDS[i]}
+		if [ $i = $COMP_CWORD ]; then
+			cword_=$j
+		fi
+	done
+}
+
+# Define preload_get_comp_words_by_ref="false", if the function
+# __perf_get_comp_words_by_ref() is required instead.
+preload_get_comp_words_by_ref="true"
+
+if [ $preload_get_comp_words_by_ref = "true" ]; then
+	type _get_comp_words_by_ref &>/dev/null ||
+	preload_get_comp_words_by_ref="false"
+fi
+[ $preload_get_comp_words_by_ref = "true" ] ||
+__perf_get_comp_words_by_ref()
+{
+	local exclude cur_ words_ cword_
+	if [ "$1" = "-n" ]; then
+		exclude=$2
+		shift 2
+	fi
+	__my_reassemble_comp_words_by_ref "$exclude"
+	cur_=${words_[cword_]}
+	while [ $# -gt 0 ]; do
+		case "$1" in
+		cur)
+			cur=$cur_
+			;;
+		prev)
+			prev=${words_[$cword_-1]}
+			;;
+		words)
+			words=("${words_[@]}")
+			;;
+		cword)
+			cword=$cword_
+			;;
+		esac
+		shift
+	done
+}
+
+# Define preload__ltrim_colon_completions="false", if the function
+# __perf__ltrim_colon_completions() is required instead.
+preload__ltrim_colon_completions="true"
+
+if [ $preload__ltrim_colon_completions = "true" ]; then
+	type __ltrim_colon_completions &>/dev/null ||
+	preload__ltrim_colon_completions="false"
+fi
+[ $preload__ltrim_colon_completions = "true" ] ||
+__perf__ltrim_colon_completions()
+{
+	if [[ "$1" == *:* && "$COMP_WORDBREAKS" == *:* ]]; then
+		# Remove colon-word prefix from COMPREPLY items
+		local colon_word=${1%"${1##*:}"}
+		local i=${#COMPREPLY[*]}
+		while [[ $((--i)) -ge 0 ]]; do
+			COMPREPLY[$i]=${COMPREPLY[$i]#"$colon_word"}
+		done
+	fi
+}
+
+__perfcomp ()
+{
+	# Expansion of spaces to array is deliberate.
+	# shellcheck disable=SC2207
+	COMPREPLY=( $( compgen -W "$1" -- "$2" ) )
+}
+
+__perfcomp_colon ()
+{
+	__perfcomp "$1" "$2"
+	if [ $preload__ltrim_colon_completions = "true" ]; then
+		__ltrim_colon_completions $cur
+	else
+		__perf__ltrim_colon_completions $cur
+	fi
+}
+
+__perf_prev_skip_opts ()
+{
+	local i cmd_ cmds_
+
+	let i=cword-1
+	cmds_=$($cmd $1 --list-cmds)
+	prev_skip_opts=""
+	while [ $i -ge 0 ]; do
+		if [[ ${words[i]} == "$1" ]]; then
+			return
+		fi
+		for cmd_ in $cmds_; do
+			if [[ ${words[i]} == "$cmd_" ]]; then
+				prev_skip_opts=${words[i]}
+				return
+			fi
+		done
+		((i--))
+	done
+}
+
+__perf_main ()
+{
+	local cmd
+
+	cmd=${words[0]}
+	COMPREPLY=()
+
+	# Skip options backward and find the last perf command
+	__perf_prev_skip_opts
+	# List perf subcommands or long options
+	if [ -z $prev_skip_opts ]; then
+		if [[ $cur == --* ]]; then
+			cmds=$($cmd --list-opts)
+		else
+			cmds=$($cmd --list-cmds)
+		fi
+		__perfcomp "$cmds" "$cur"
+	# List possible events for -e option
+	elif [[ $prev == @("-e"|"--event") &&
+		$prev_skip_opts == @(record|stat|top) ]]; then
+
+		local cur1=${COMP_WORDS[COMP_CWORD]}
+		local raw_evts
+		local arr s tmp result cpu_evts
+
+		raw_evts=$($cmd list --raw-dump hw sw cache tracepoint pmu sdt)
+		# aarch64 doesn't have /sys/bus/event_source/devices/cpu/events
+		if [[ `uname -m` != aarch64 ]]; then
+			cpu_evts=$(ls /sys/bus/event_source/devices/cpu/events)
+		fi
+
+		if [[ "$cur1" == */* && ${cur1#*/} =~ ^[A-Z] ]]; then
+			OLD_IFS="$IFS"
+			IFS=" "
+			# Expansion of spaces to array is deliberate.
+			# shellcheck disable=SC2206
+			arr=($raw_evts)
+			IFS="$OLD_IFS"
+
+			for s in "${arr[@]}"
+			do
+				if [[ "$s" == *cpu/* ]]; then
+					tmp=${s#*cpu/}
+					result=$result" ""cpu/"${tmp^^}
+				else
+					result=$result" "$s
+				fi
+			done
+
+			evts=${result}" "${cpu_evts}
+		else
+			evts=${raw_evts}" "${cpu_evts}
+		fi
+
+		if [[ "$cur1" == , ]]; then
+			__perfcomp_colon "$evts" ""
+		else
+			__perfcomp_colon "$evts" "$cur1"
+		fi
+	elif [[ $prev == @("--pfm-events") &&
+		$prev_skip_opts == @(record|stat|top) ]]; then
+		local evts
+		evts=$($cmd list --raw-dump pfm)
+		__perfcomp "$evts" "$cur"
+	elif [[ $prev == @("-M"|"--metrics") &&
+		$prev_skip_opts == @(stat) ]]; then
+		local metrics
+		metrics=$($cmd list --raw-dump metric metricgroup)
+		__perfcomp "$metrics" "$cur"
+	else
+		# List subcommands for perf commands
+		if [[ $prev_skip_opts == @(kvm|kmem|mem|lock|sched|
+			|data|help|script|test|timechart|trace) ]]; then
+			subcmds=$($cmd $prev_skip_opts --list-cmds)
+			__perfcomp_colon "$subcmds" "$cur"
+		fi
+		# List long option names
+		if [[ $cur == --* ]];  then
+			subcmd=$prev_skip_opts
+			__perf_prev_skip_opts $subcmd
+			subcmd=$subcmd" "$prev_skip_opts
+			opts=$($cmd $subcmd --list-opts)
+			__perfcomp "$opts" "$cur"
+		fi
+	fi
+}
+
+if [[ -n ${ZSH_VERSION-} ]]; then
+	autoload -U +X compinit && compinit
+
+	__perfcomp ()
+	{
+		emulate -L zsh
+
+		local c IFS=$' \t\n'
+		local -a array
+
+		for c in ${=1}; do
+			case $c in
+			--*=*|*.) ;;
+			*) c="$c " ;;
+			esac
+			array[${#array[@]}+1]="$c"
+		done
+
+		compset -P '*[=:]'
+		compadd -Q -S '' -a -- array && _ret=0
+	}
+
+	__perfcomp_colon ()
+	{
+		emulate -L zsh
+
+		local cur_="${2-$cur}"
+		local c IFS=$' \t\n'
+		local -a array
+
+		if [[ "$cur_" == *:* ]]; then
+			local colon_word=${cur_%"${cur_##*:}"}
+		fi
+
+		for c in ${=1}; do
+			case $c in
+			--*=*|*.) ;;
+			*) c="$c " ;;
+			esac
+			array[$#array+1]=${c#"$colon_word"}
+		done
+
+		compset -P '*[=:]'
+		compadd -Q -S '' -a -- array && _ret=0
+	}
+
+	_perf ()
+	{
+		local _ret=1 cur cword prev
+		cur=${words[CURRENT]}
+		prev=${words[CURRENT-1]}
+		let cword=CURRENT-1
+		emulate ksh -c __perf_main
+		let _ret && _default && _ret=0
+		# _ret is only assigned 0 or 1, disable inaccurate analysis.
+		# shellcheck disable=SC2152
+		return _ret
+	}
+
+	compdef _perf perf
+	return
+fi
+
+type perf &>/dev/null &&
+_perf()
+{
+	if [[ "$COMP_WORDBREAKS" != *,* ]]; then
+		COMP_WORDBREAKS="${COMP_WORDBREAKS},"
+		export COMP_WORDBREAKS
+	fi
+
+	if [[ "$COMP_WORDBREAKS" == *:* ]]; then
+		COMP_WORDBREAKS="${COMP_WORDBREAKS/:/}"
+		export COMP_WORDBREAKS
+	fi
+
+	local cur words cword prev
+	if [ $preload_get_comp_words_by_ref = "true" ]; then
+		_get_comp_words_by_ref -n =:, cur words cword prev
+	else
+		__perf_get_comp_words_by_ref -n =:, cur words cword prev
+	fi
+	__perf_main
+} &&
+
+complete -o bashdefault -o default -o nospace -F _perf perf 2>/dev/null \
+	|| complete -o default -o nospace -F _perf perf