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>

5 files changed, 365 insertions, 0 deletions

diff --git a/tools/leds/.gitignore b/tools/leds/.gitignore
new file mode 100644
index 000000000..06bd3ee1b
--- /dev/null
+++ b/tools/leds/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+uledmon
diff --git a/tools/leds/Makefile b/tools/leds/Makefile
new file mode 100644
index 000000000..7b6bed13d
--- /dev/null
+++ b/tools/leds/Makefile
@@ -0,0 +1,13 @@
+# SPDX-License-Identifier: GPL-2.0
+# Makefile for LEDs tools
+
+CFLAGS = -Wall -Wextra -g -I../../include/uapi
+
+all: uledmon led_hw_brightness_mon
+%: %.c
+	$(CC) $(CFLAGS) -o $@ $^
+
+clean:
+	$(RM) uledmon led_hw_brightness_mon
+
+.PHONY: all clean
diff --git a/tools/leds/get_led_device_info.sh b/tools/leds/get_led_device_info.sh
new file mode 100755
index 000000000..ccfa442db
--- /dev/null
+++ b/tools/leds/get_led_device_info.sh
@@ -0,0 +1,201 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+led_common_defs_path="include/dt-bindings/leds/common.h"
+
+num_args=$#
+if [ $num_args -eq 1 ]; then
+        linux_top=$(dirname `realpath $0` | awk -F/     \
+                        '{                              \
+                                i=1;                    \
+                                while (i <= NF - 2) {   \
+                                        printf $i"/";   \
+                                        i++;            \
+                                };                      \
+                        }')
+	led_defs_path=$linux_top/$led_common_defs_path
+elif [ $num_args -eq 2 ]; then
+        led_defs_path=`realpath $2`
+else
+	echo "Usage: get_led_device_info.sh LED_CDEV_PATH [LED_COMMON_DEFS_PATH]"
+	exit 1
+fi
+
+if [ ! -f $led_defs_path ]; then
+	echo "$led_defs_path doesn't exist"
+	exit 1
+fi
+
+led_cdev_path=`echo $1 | sed s'/\/$//'`
+
+ls "$led_cdev_path/brightness" > /dev/null 2>&1
+if [ $? -ne 0 ]; then
+	echo "Device \"$led_cdev_path\" does not exist."
+	exit 1
+fi
+
+bus=`readlink $led_cdev_path/device/subsystem | sed s'/.*\///'`
+usb_subdev=`readlink $led_cdev_path | grep usb | sed s'/\(.*usb[0-9]*\/[0-9]*-[0-9]*\)\/.*/\1/'`
+ls "$led_cdev_path/device/of_node/compatible" > /dev/null 2>&1
+of_node_missing=$?
+
+if [ "$bus" = "input" ]; then
+	input_node=`readlink $led_cdev_path/device | sed s'/.*\///'`
+	if [ ! -z "$usb_subdev" ]; then
+		bus="usb"
+	fi
+fi
+
+if [ "$bus" = "usb" ]; then
+	usb_interface=`readlink $led_cdev_path | sed s'/.*\(usb[0-9]*\)/\1/' | cut -d\/ -f3`
+	cd $led_cdev_path/../$usb_subdev
+	driver=`readlink $usb_interface/driver | sed s'/.*\///'`
+	if [ -d "$usb_interface/ieee80211" ]; then
+		wifi_phy=`ls -l $usb_interface/ieee80211 | grep phy | awk '{print $9}'`
+	fi
+	idVendor=`cat idVendor`
+	idProduct=`cat idProduct`
+	manufacturer=`cat manufacturer`
+	product=`cat product`
+elif [ "$bus" = "input" ]; then
+	cd $led_cdev_path
+	product=`cat device/name`
+	driver=`cat device/device/driver/description`
+elif [ $of_node_missing -eq 0 ]; then
+	cd $led_cdev_path
+	compatible=`cat device/of_node/compatible`
+	if [ "$compatible" = "gpio-leds" ]; then
+		driver="leds-gpio"
+	elif [ "$compatible" = "pwm-leds" ]; then
+		driver="leds-pwm"
+	else
+		manufacturer=`echo $compatible | awk -F, '{print $1}'`
+		product=`echo $compatible | awk -F, '{print $2}'`
+	fi
+else
+	echo "Unknown device type."
+	exit 1
+fi
+
+printf "\n#####################################\n"
+printf "# LED class device hardware details #\n"
+printf "#####################################\n\n"
+
+printf "bus:\t\t\t$bus\n"
+
+if [ ! -z "$idVendor" ]; then
+	printf "idVendor:\t\t$idVendor\n"
+fi
+
+if [ ! -z "$idProduct" ]; then
+	printf "idProduct:\t\t$idProduct\n"
+fi
+
+if [ ! -z "$manufacturer" ]; then
+	printf "manufacturer:\t\t$manufacturer\n"
+fi
+
+if [ ! -z "$product" ]; then
+	printf "product:\t\t$product\n"
+fi
+
+if [ ! -z "$driver" ]; then
+	printf "driver:\t\t\t$driver\n"
+fi
+
+if [ ! -z "$input_node" ]; then
+	printf "associated input node:\t$input_node\n"
+fi
+
+printf "\n####################################\n"
+printf "# LED class device name validation #\n"
+printf "####################################\n\n"
+
+led_name=`echo $led_cdev_path | sed s'/.*\///'`
+
+num_sections=`echo $led_name | awk -F: '{print NF}'`
+
+if [ $num_sections -eq 1 ]; then
+	printf "\":\" delimiter not detected.\t[ FAILED ]\n"
+	exit 1
+elif [ $num_sections -eq 2 ]; then
+	color=`echo $led_name | cut -d: -f1`
+	function=`echo $led_name | cut -d: -f2`
+elif [ $num_sections -eq 3 ]; then
+	devicename=`echo $led_name | cut -d: -f1`
+	color=`echo $led_name | cut -d: -f2`
+	function=`echo $led_name | cut -d: -f3`
+else
+	printf "Detected %d sections in the LED class device name - should the script be updated?\n" $num_sections
+	exit 1
+fi
+
+S_DEV="devicename"
+S_CLR="color     "
+S_FUN="function  "
+status_tab=20
+
+print_msg_ok()
+{
+	local section_name="$1"
+	local section_val="$2"
+	local msg="$3"
+	printf "$section_name :\t%-${status_tab}.${status_tab}s %s %s\n" "$section_val" "[ OK ]    " "$msg"
+}
+
+print_msg_failed()
+{
+	local section_name="$1"
+	local section_val="$2"
+	local msg="$3"
+	printf "$section_name :\t%-${status_tab}.${status_tab}s %s %s\n" "$section_val" "[ FAILED ]" "$msg"
+}
+
+if [ ! -z "$input_node" ]; then
+	expected_devname=$input_node
+elif [ ! -z "$wifi_phy" ]; then
+	expected_devname=$wifi_phy
+fi
+
+if [ ! -z "$devicename" ]; then
+	if [ ! -z "$expected_devname" ]; then
+		if [ "$devicename" = "$expected_devname" ]; then
+			print_msg_ok "$S_DEV" "$devicename"
+		else
+			print_msg_failed "$S_DEV" "$devicename" "Expected: $expected_devname"
+		fi
+	else
+		if [ "$devicename" = "$manufacturer" ]; then
+			print_msg_failed "$S_DEV" "$devicename" "Redundant: use of vendor name is discouraged"
+		elif [ "$devicename" = "$product" ]; then
+			print_msg_failed "$S_DEV" "$devicename" "Redundant: use of product name is discouraged"
+		else
+			print_msg_failed "$S_DEV" "$devicename" "Unknown devicename - should the script be updated?"
+		fi
+	fi
+elif [ ! -z "$expected_devname" ]; then
+	print_msg_failed "$S_DEV" "blank" "Expected: $expected_devname"
+fi
+
+if [ ! -z "$color" ]; then
+	color_upper=`echo $color | tr [:lower:] [:upper:]`
+	color_id_definition=$(cat $led_defs_path | grep "_$color_upper\s" | awk '{print $2}')
+	if [ ! -z "$color_id_definition" ]; then
+		print_msg_ok "$S_CLR" "$color" "Matching definition: $color_id_definition"
+	else
+		print_msg_failed "$S_CLR" "$color" "Definition not found in $led_defs_path"
+	fi
+
+fi
+
+if [ ! -z "$function" ]; then
+	# strip optional enumerator
+	function=`echo $function | sed s'/\(.*\)-[0-9]*$/\1/'`
+	fun_definition=$(cat $led_defs_path | grep "\"$function\"" | awk '{print $2}')
+	if [ ! -z "$fun_definition" ]; then
+		print_msg_ok "$S_FUN" "$function" "Matching definition: $fun_definition"
+	else
+		print_msg_failed "$S_FUN" "$function" "Definition not found in $led_defs_path"
+	fi
+
+fi
diff --git a/tools/leds/led_hw_brightness_mon.c b/tools/leds/led_hw_brightness_mon.c
new file mode 100644
index 000000000..eb65ae988
--- /dev/null
+++ b/tools/leds/led_hw_brightness_mon.c
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * led_hw_brightness_mon.c
+ *
+ * This program monitors LED brightness level changes having its origin
+ * in hardware/firmware, i.e. outside of kernel control.
+ * A timestamp and brightness value is printed each time the brightness changes.
+ *
+ * Usage: led_hw_brightness_mon <device-name>
+ *
+ * <device-name> is the name of the LED class device to be monitored. Pressing
+ * CTRL+C will exit.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <linux/uleds.h>
+
+int main(int argc, char const *argv[])
+{
+	int fd, ret;
+	char brightness_file_path[LED_MAX_NAME_SIZE + 11];
+	struct pollfd pollfd;
+	struct timespec ts;
+	char buf[11];
+
+	if (argc != 2) {
+		fprintf(stderr, "Requires <device-name> argument\n");
+		return 1;
+	}
+
+	snprintf(brightness_file_path, LED_MAX_NAME_SIZE,
+		 "/sys/class/leds/%s/brightness_hw_changed", argv[1]);
+
+	fd = open(brightness_file_path, O_RDONLY);
+	if (fd == -1) {
+		printf("Failed to open %s file\n", brightness_file_path);
+		return 1;
+	}
+
+	/*
+	 * read may fail if no hw brightness change has occurred so far,
+	 * but it is required to avoid spurious poll notifications in
+	 * the opposite case.
+	 */
+	read(fd, buf, sizeof(buf));
+
+	pollfd.fd = fd;
+	pollfd.events = POLLPRI;
+
+	while (1) {
+		ret = poll(&pollfd, 1, -1);
+		if (ret == -1) {
+			printf("Failed to poll %s file (%d)\n",
+				brightness_file_path, ret);
+			ret = 1;
+			break;
+		}
+
+		clock_gettime(CLOCK_MONOTONIC, &ts);
+
+		ret = read(fd, buf, sizeof(buf));
+		if (ret < 0)
+			break;
+
+		ret = lseek(pollfd.fd, 0, SEEK_SET);
+		if (ret < 0) {
+			printf("lseek failed (%d)\n", ret);
+			break;
+		}
+
+		printf("[%ld.%09ld] %d\n", ts.tv_sec, ts.tv_nsec, atoi(buf));
+	}
+
+	close(fd);
+
+	return ret;
+}
diff --git a/tools/leds/uledmon.c b/tools/leds/uledmon.c
new file mode 100644
index 000000000..c15a39c1f
--- /dev/null
+++ b/tools/leds/uledmon.c
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * uledmon.c
+ *
+ * This program creates a new userspace LED class device and monitors it. A
+ * timestamp and brightness value is printed each time the brightness changes.
+ *
+ * Usage: uledmon <device-name>
+ *
+ * <device-name> is the name of the LED class device to be created. Pressing
+ * CTRL+C will exit.
+ */
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <linux/uleds.h>
+
+int main(int argc, char const *argv[])
+{
+	struct uleds_user_dev uleds_dev;
+	int fd, ret;
+	int brightness;
+	struct timespec ts;
+
+	if (argc != 2) {
+		fprintf(stderr, "Requires <device-name> argument\n");
+		return 1;
+	}
+
+	strncpy(uleds_dev.name, argv[1], LED_MAX_NAME_SIZE);
+	uleds_dev.max_brightness = 100;
+
+	fd = open("/dev/uleds", O_RDWR);
+	if (fd == -1) {
+		perror("Failed to open /dev/uleds");
+		return 1;
+	}
+
+	ret = write(fd, &uleds_dev, sizeof(uleds_dev));
+	if (ret == -1) {
+		perror("Failed to write to /dev/uleds");
+		close(fd);
+		return 1;
+	}
+
+	while (1) {
+		ret = read(fd, &brightness, sizeof(brightness));
+		if (ret == -1) {
+			perror("Failed to read from /dev/uleds");
+			close(fd);
+			return 1;
+		}
+		clock_gettime(CLOCK_MONOTONIC, &ts);
+		printf("[%ld.%09ld] %u\n", ts.tv_sec, ts.tv_nsec, brightness);
+	}
+
+	close(fd);
+
+	return 0;
+}