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, 304 insertions, 0 deletions

diff --git a/drivers/input/misc/apanel.c b/drivers/input/misc/apanel.c
new file mode 100644
index 000000000..3eb02a64a
--- /dev/null
+++ b/drivers/input/misc/apanel.c
@@ -0,0 +1,304 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Fujitsu Lifebook Application Panel button drive
+ *
+ *  Copyright (C) 2007 Stephen Hemminger <shemminger@linux-foundation.org>
+ *  Copyright (C) 2001-2003 Jochen Eisinger <jochen@penguin-breeder.org>
+ *
+ * Many Fujitsu Lifebook laptops have a small panel of buttons that are
+ * accessible via the i2c/smbus interface. This driver polls those
+ * buttons and generates input events.
+ *
+ * For more details see:
+ *	http://apanel.sourceforge.net/tech.php
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/ioport.h>
+#include <linux/io.h>
+#include <linux/input.h>
+#include <linux/i2c.h>
+#include <linux/leds.h>
+
+#define APANEL_NAME	"Fujitsu Application Panel"
+#define APANEL		"apanel"
+
+/* How often we poll keys - msecs */
+#define POLL_INTERVAL_DEFAULT	1000
+
+/* Magic constants in BIOS that tell about buttons */
+enum apanel_devid {
+	APANEL_DEV_NONE	  = 0,
+	APANEL_DEV_APPBTN = 1,
+	APANEL_DEV_CDBTN  = 2,
+	APANEL_DEV_LCD	  = 3,
+	APANEL_DEV_LED	  = 4,
+
+	APANEL_DEV_MAX,
+};
+
+enum apanel_chip {
+	CHIP_NONE    = 0,
+	CHIP_OZ992C  = 1,
+	CHIP_OZ163T  = 2,
+	CHIP_OZ711M3 = 4,
+};
+
+/* Result of BIOS snooping/probing -- what features are supported */
+static enum apanel_chip device_chip[APANEL_DEV_MAX];
+
+#define MAX_PANEL_KEYS	12
+
+struct apanel {
+	struct input_dev *idev;
+	struct i2c_client *client;
+	unsigned short keymap[MAX_PANEL_KEYS];
+	u16 nkeys;
+	struct led_classdev mail_led;
+};
+
+static const unsigned short apanel_keymap[MAX_PANEL_KEYS] = {
+	[0] = KEY_MAIL,
+	[1] = KEY_WWW,
+	[2] = KEY_PROG2,
+	[3] = KEY_PROG1,
+
+	[8] = KEY_FORWARD,
+	[9] = KEY_REWIND,
+	[10] = KEY_STOPCD,
+	[11] = KEY_PLAYPAUSE,
+};
+
+static void report_key(struct input_dev *input, unsigned keycode)
+{
+	dev_dbg(input->dev.parent, "report key %#x\n", keycode);
+	input_report_key(input, keycode, 1);
+	input_sync(input);
+
+	input_report_key(input, keycode, 0);
+	input_sync(input);
+}
+
+/* Poll for key changes
+ *
+ * Read Application keys via SMI
+ *  A (0x4), B (0x8), Internet (0x2), Email (0x1).
+ *
+ * CD keys:
+ * Forward (0x100), Rewind (0x200), Stop (0x400), Pause (0x800)
+ */
+static void apanel_poll(struct input_dev *idev)
+{
+	struct apanel *ap = input_get_drvdata(idev);
+	u8 cmd = device_chip[APANEL_DEV_APPBTN] == CHIP_OZ992C ? 0 : 8;
+	s32 data;
+	int i;
+
+	data = i2c_smbus_read_word_data(ap->client, cmd);
+	if (data < 0)
+		return;	/* ignore errors (due to ACPI??) */
+
+	/* write back to clear latch */
+	i2c_smbus_write_word_data(ap->client, cmd, 0);
+
+	if (!data)
+		return;
+
+	dev_dbg(&idev->dev, APANEL ": data %#x\n", data);
+	for (i = 0; i < idev->keycodemax; i++)
+		if ((1u << i) & data)
+			report_key(idev, ap->keymap[i]);
+}
+
+static int mail_led_set(struct led_classdev *led,
+			 enum led_brightness value)
+{
+	struct apanel *ap = container_of(led, struct apanel, mail_led);
+	u16 led_bits = value != LED_OFF ? 0x8000 : 0x0000;
+
+	return i2c_smbus_write_word_data(ap->client, 0x10, led_bits);
+}
+
+static int apanel_probe(struct i2c_client *client)
+{
+	struct apanel *ap;
+	struct input_dev *idev;
+	u8 cmd = device_chip[APANEL_DEV_APPBTN] == CHIP_OZ992C ? 0 : 8;
+	int i, err;
+
+	ap = devm_kzalloc(&client->dev, sizeof(*ap), GFP_KERNEL);
+	if (!ap)
+		return -ENOMEM;
+
+	idev = devm_input_allocate_device(&client->dev);
+	if (!idev)
+		return -ENOMEM;
+
+	ap->idev = idev;
+	ap->client = client;
+
+	i2c_set_clientdata(client, ap);
+
+	err = i2c_smbus_write_word_data(client, cmd, 0);
+	if (err) {
+		dev_warn(&client->dev, "smbus write error %d\n", err);
+		return err;
+	}
+
+	input_set_drvdata(idev, ap);
+
+	idev->name = APANEL_NAME " buttons";
+	idev->phys = "apanel/input0";
+	idev->id.bustype = BUS_HOST;
+
+	memcpy(ap->keymap, apanel_keymap, sizeof(apanel_keymap));
+	idev->keycode = ap->keymap;
+	idev->keycodesize = sizeof(ap->keymap[0]);
+	idev->keycodemax = (device_chip[APANEL_DEV_CDBTN] != CHIP_NONE) ? 12 : 4;
+
+	set_bit(EV_KEY, idev->evbit);
+	for (i = 0; i < idev->keycodemax; i++)
+		if (ap->keymap[i])
+			set_bit(ap->keymap[i], idev->keybit);
+
+	err = input_setup_polling(idev, apanel_poll);
+	if (err)
+		return err;
+
+	input_set_poll_interval(idev, POLL_INTERVAL_DEFAULT);
+
+	err = input_register_device(idev);
+	if (err)
+		return err;
+
+	if (device_chip[APANEL_DEV_LED] != CHIP_NONE) {
+		ap->mail_led.name = "mail:blue";
+		ap->mail_led.brightness_set_blocking = mail_led_set;
+		err = devm_led_classdev_register(&client->dev, &ap->mail_led);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+static void apanel_shutdown(struct i2c_client *client)
+{
+	struct apanel *ap = i2c_get_clientdata(client);
+
+	if (device_chip[APANEL_DEV_LED] != CHIP_NONE)
+		led_set_brightness(&ap->mail_led, LED_OFF);
+}
+
+static const struct i2c_device_id apanel_id[] = {
+	{ .name = "fujitsu_apanel" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, apanel_id);
+
+static struct i2c_driver apanel_driver = {
+	.driver = {
+		.name = APANEL,
+	},
+	.probe		= apanel_probe,
+	.shutdown	= apanel_shutdown,
+	.id_table	= apanel_id,
+};
+
+/* Scan the system ROM for the signature "FJKEYINF" */
+static __init const void __iomem *bios_signature(const void __iomem *bios)
+{
+	ssize_t offset;
+	const unsigned char signature[] = "FJKEYINF";
+
+	for (offset = 0; offset < 0x10000; offset += 0x10) {
+		if (check_signature(bios + offset, signature,
+				    sizeof(signature)-1))
+			return bios + offset;
+	}
+	pr_notice(APANEL ": Fujitsu BIOS signature '%s' not found...\n",
+		  signature);
+	return NULL;
+}
+
+static int __init apanel_init(void)
+{
+	void __iomem *bios;
+	const void __iomem *p;
+	u8 devno;
+	unsigned char i2c_addr;
+	int found = 0;
+
+	bios = ioremap(0xF0000, 0x10000); /* Can't fail */
+
+	p = bios_signature(bios);
+	if (!p) {
+		iounmap(bios);
+		return -ENODEV;
+	}
+
+	/* just use the first address */
+	p += 8;
+	i2c_addr = readb(p + 3) >> 1;
+
+	for ( ; (devno = readb(p)) & 0x7f; p += 4) {
+		unsigned char method, slave, chip;
+
+		method = readb(p + 1);
+		chip = readb(p + 2);
+		slave = readb(p + 3) >> 1;
+
+		if (slave != i2c_addr) {
+			pr_notice(APANEL ": only one SMBus slave "
+				  "address supported, skipping device...\n");
+			continue;
+		}
+
+		/* translate alternative device numbers */
+		switch (devno) {
+		case 6:
+			devno = APANEL_DEV_APPBTN;
+			break;
+		case 7:
+			devno = APANEL_DEV_LED;
+			break;
+		}
+
+		if (devno >= APANEL_DEV_MAX)
+			pr_notice(APANEL ": unknown device %u found\n", devno);
+		else if (device_chip[devno] != CHIP_NONE)
+			pr_warn(APANEL ": duplicate entry for devno %u\n",
+				devno);
+
+		else if (method != 1 && method != 2 && method != 4) {
+			pr_notice(APANEL ": unknown method %u for devno %u\n",
+				  method, devno);
+		} else {
+			device_chip[devno] = (enum apanel_chip) chip;
+			++found;
+		}
+	}
+	iounmap(bios);
+
+	if (found == 0) {
+		pr_info(APANEL ": no input devices reported by BIOS\n");
+		return -EIO;
+	}
+
+	return i2c_add_driver(&apanel_driver);
+}
+module_init(apanel_init);
+
+static void __exit apanel_cleanup(void)
+{
+	i2c_del_driver(&apanel_driver);
+}
+module_exit(apanel_cleanup);
+
+MODULE_AUTHOR("Stephen Hemminger <shemminger@linux-foundation.org>");
+MODULE_DESCRIPTION(APANEL_NAME " driver");
+MODULE_LICENSE("GPL");
+
+MODULE_ALIAS("dmi:*:svnFUJITSU:pnLifeBook*:pvr*:rvnFUJITSU:*");
+MODULE_ALIAS("dmi:*:svnFUJITSU:pnLifebook*:pvr*:rvnFUJITSU:*");