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, 406 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/elo.c b/drivers/input/touchscreen/elo.c
new file mode 100644
index 000000000..97aeec7ef
--- /dev/null
+++ b/drivers/input/touchscreen/elo.c
@@ -0,0 +1,406 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Elo serial touchscreen driver
+ *
+ * Copyright (c) 2004 Vojtech Pavlik
+ */
+
+
+/*
+ * This driver can handle serial Elo touchscreens using either the Elo standard
+ * 'E271-2210' 10-byte protocol, Elo legacy 'E281A-4002' 6-byte protocol, Elo
+ * legacy 'E271-140' 4-byte protocol and Elo legacy 'E261-280' 3-byte protocol.
+ */
+
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/serio.h>
+#include <linux/ctype.h>
+
+#define DRIVER_DESC	"Elo serial touchscreen driver"
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+/*
+ * Definitions & global arrays.
+ */
+
+#define ELO_MAX_LENGTH		10
+
+#define ELO10_PACKET_LEN	8
+#define ELO10_TOUCH		0x03
+#define ELO10_PRESSURE		0x80
+
+#define ELO10_LEAD_BYTE		'U'
+
+#define ELO10_ID_CMD		'i'
+
+#define ELO10_TOUCH_PACKET	'T'
+#define ELO10_ACK_PACKET	'A'
+#define ELI10_ID_PACKET		'I'
+
+/*
+ * Per-touchscreen data.
+ */
+
+struct elo {
+	struct input_dev *dev;
+	struct serio *serio;
+	struct mutex cmd_mutex;
+	struct completion cmd_done;
+	int id;
+	int idx;
+	unsigned char expected_packet;
+	unsigned char csum;
+	unsigned char data[ELO_MAX_LENGTH];
+	unsigned char response[ELO10_PACKET_LEN];
+	char phys[32];
+};
+
+static void elo_process_data_10(struct elo *elo, unsigned char data)
+{
+	struct input_dev *dev = elo->dev;
+
+	elo->data[elo->idx] = data;
+
+	switch (elo->idx++) {
+	case 0:
+		elo->csum = 0xaa;
+		if (data != ELO10_LEAD_BYTE) {
+			dev_dbg(&elo->serio->dev,
+				"unsynchronized data: 0x%02x\n", data);
+			elo->idx = 0;
+		}
+		break;
+
+	case 9:
+		elo->idx = 0;
+		if (data != elo->csum) {
+			dev_dbg(&elo->serio->dev,
+				"bad checksum: 0x%02x, expected 0x%02x\n",
+				 data, elo->csum);
+			break;
+		}
+		if (elo->data[1] != elo->expected_packet) {
+			if (elo->data[1] != ELO10_TOUCH_PACKET)
+				dev_dbg(&elo->serio->dev,
+					"unexpected packet: 0x%02x\n",
+					 elo->data[1]);
+			break;
+		}
+		if (likely(elo->data[1] == ELO10_TOUCH_PACKET)) {
+			input_report_abs(dev, ABS_X, (elo->data[4] << 8) | elo->data[3]);
+			input_report_abs(dev, ABS_Y, (elo->data[6] << 8) | elo->data[5]);
+			if (elo->data[2] & ELO10_PRESSURE)
+				input_report_abs(dev, ABS_PRESSURE,
+						(elo->data[8] << 8) | elo->data[7]);
+			input_report_key(dev, BTN_TOUCH, elo->data[2] & ELO10_TOUCH);
+			input_sync(dev);
+		} else if (elo->data[1] == ELO10_ACK_PACKET) {
+			if (elo->data[2] == '0')
+				elo->expected_packet = ELO10_TOUCH_PACKET;
+			complete(&elo->cmd_done);
+		} else {
+			memcpy(elo->response, &elo->data[1], ELO10_PACKET_LEN);
+			elo->expected_packet = ELO10_ACK_PACKET;
+		}
+		break;
+	}
+	elo->csum += data;
+}
+
+static void elo_process_data_6(struct elo *elo, unsigned char data)
+{
+	struct input_dev *dev = elo->dev;
+
+	elo->data[elo->idx] = data;
+
+	switch (elo->idx++) {
+
+	case 0:
+		if ((data & 0xc0) != 0xc0)
+			elo->idx = 0;
+		break;
+
+	case 1:
+		if ((data & 0xc0) != 0x80)
+			elo->idx = 0;
+		break;
+
+	case 2:
+		if ((data & 0xc0) != 0x40)
+			elo->idx = 0;
+		break;
+
+	case 3:
+		if (data & 0xc0) {
+			elo->idx = 0;
+			break;
+		}
+
+		input_report_abs(dev, ABS_X, ((elo->data[0] & 0x3f) << 6) | (elo->data[1] & 0x3f));
+		input_report_abs(dev, ABS_Y, ((elo->data[2] & 0x3f) << 6) | (elo->data[3] & 0x3f));
+
+		if (elo->id == 2) {
+			input_report_key(dev, BTN_TOUCH, 1);
+			input_sync(dev);
+			elo->idx = 0;
+		}
+
+		break;
+
+	case 4:
+		if (data) {
+			input_sync(dev);
+			elo->idx = 0;
+		}
+		break;
+
+	case 5:
+		if ((data & 0xf0) == 0) {
+			input_report_abs(dev, ABS_PRESSURE, elo->data[5]);
+			input_report_key(dev, BTN_TOUCH, !!elo->data[5]);
+		}
+		input_sync(dev);
+		elo->idx = 0;
+		break;
+	}
+}
+
+static void elo_process_data_3(struct elo *elo, unsigned char data)
+{
+	struct input_dev *dev = elo->dev;
+
+	elo->data[elo->idx] = data;
+
+	switch (elo->idx++) {
+
+	case 0:
+		if ((data & 0x7f) != 0x01)
+			elo->idx = 0;
+		break;
+	case 2:
+		input_report_key(dev, BTN_TOUCH, !(elo->data[1] & 0x80));
+		input_report_abs(dev, ABS_X, elo->data[1]);
+		input_report_abs(dev, ABS_Y, elo->data[2]);
+		input_sync(dev);
+		elo->idx = 0;
+		break;
+	}
+}
+
+static irqreturn_t elo_interrupt(struct serio *serio,
+		unsigned char data, unsigned int flags)
+{
+	struct elo *elo = serio_get_drvdata(serio);
+
+	switch (elo->id) {
+	case 0:
+		elo_process_data_10(elo, data);
+		break;
+
+	case 1:
+	case 2:
+		elo_process_data_6(elo, data);
+		break;
+
+	case 3:
+		elo_process_data_3(elo, data);
+		break;
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int elo_command_10(struct elo *elo, unsigned char *packet)
+{
+	int error;
+	int i;
+	unsigned char csum = 0xaa + ELO10_LEAD_BYTE;
+
+	guard(mutex)(&elo->cmd_mutex);
+
+	scoped_guard(serio_pause_rx, elo->serio) {
+		elo->expected_packet = toupper(packet[0]);
+		init_completion(&elo->cmd_done);
+	}
+
+	error = serio_write(elo->serio, ELO10_LEAD_BYTE);
+	if (error)
+		return error;
+
+	for (i = 0; i < ELO10_PACKET_LEN; i++) {
+		csum += packet[i];
+		error = serio_write(elo->serio, packet[i]);
+		if (error)
+			return error;
+	}
+
+	error = serio_write(elo->serio, csum);
+	if (error)
+		return error;
+
+	wait_for_completion_timeout(&elo->cmd_done, HZ);
+
+	if (elo->expected_packet != ELO10_TOUCH_PACKET)
+		return -EIO;
+
+	/* We are back in reporting mode, the command was ACKed */
+	memcpy(packet, elo->response, ELO10_PACKET_LEN);
+	return 0;
+}
+
+static int elo_setup_10(struct elo *elo)
+{
+	static const char * const elo_types[] = { "Accu", "Dura", "Intelli", "Carroll" };
+	struct input_dev *dev = elo->dev;
+	unsigned char packet[ELO10_PACKET_LEN] = { ELO10_ID_CMD };
+
+	if (elo_command_10(elo, packet))
+		return -1;
+
+	dev->id.version = (packet[5] << 8) | packet[4];
+
+	input_set_abs_params(dev, ABS_X, 96, 4000, 0, 0);
+	input_set_abs_params(dev, ABS_Y, 96, 4000, 0, 0);
+	if (packet[3] & ELO10_PRESSURE)
+		input_set_abs_params(dev, ABS_PRESSURE, 0, 255, 0, 0);
+
+	dev_info(&elo->serio->dev,
+		 "%sTouch touchscreen, fw: %02x.%02x, features: 0x%02x, controller: 0x%02x\n",
+		 elo_types[(packet[1] - '0') & 0x03],
+		 packet[5], packet[4], packet[3], packet[7]);
+
+	return 0;
+}
+
+/*
+ * elo_disconnect() is the opposite of elo_connect()
+ */
+
+static void elo_disconnect(struct serio *serio)
+{
+	struct elo *elo = serio_get_drvdata(serio);
+
+	input_get_device(elo->dev);
+	input_unregister_device(elo->dev);
+	serio_close(serio);
+	serio_set_drvdata(serio, NULL);
+	input_put_device(elo->dev);
+	kfree(elo);
+}
+
+/*
+ * elo_connect() is the routine that is called when someone adds a
+ * new serio device that supports Gunze protocol and registers it as
+ * an input device.
+ */
+
+static int elo_connect(struct serio *serio, struct serio_driver *drv)
+{
+	struct elo *elo;
+	struct input_dev *input_dev;
+	int err;
+
+	elo = kzalloc_obj(*elo);
+	input_dev = input_allocate_device();
+	if (!elo || !input_dev) {
+		err = -ENOMEM;
+		goto fail1;
+	}
+
+	elo->serio = serio;
+	elo->id = serio->id.id;
+	elo->dev = input_dev;
+	elo->expected_packet = ELO10_TOUCH_PACKET;
+	mutex_init(&elo->cmd_mutex);
+	init_completion(&elo->cmd_done);
+	scnprintf(elo->phys, sizeof(elo->phys), "%s/input0", serio->phys);
+
+	input_dev->name = "Elo Serial TouchScreen";
+	input_dev->phys = elo->phys;
+	input_dev->id.bustype = BUS_RS232;
+	input_dev->id.vendor = SERIO_ELO;
+	input_dev->id.product = elo->id;
+	input_dev->id.version = 0x0100;
+	input_dev->dev.parent = &serio->dev;
+
+	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
+	input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
+
+	serio_set_drvdata(serio, elo);
+	err = serio_open(serio, drv);
+	if (err)
+		goto fail2;
+
+	switch (elo->id) {
+
+	case 0: /* 10-byte protocol */
+		if (elo_setup_10(elo)) {
+			err = -EIO;
+			goto fail3;
+		}
+
+		break;
+
+	case 1: /* 6-byte protocol */
+		input_set_abs_params(input_dev, ABS_PRESSURE, 0, 15, 0, 0);
+		fallthrough;
+
+	case 2: /* 4-byte protocol */
+		input_set_abs_params(input_dev, ABS_X, 96, 4000, 0, 0);
+		input_set_abs_params(input_dev, ABS_Y, 96, 4000, 0, 0);
+		break;
+
+	case 3: /* 3-byte protocol */
+		input_set_abs_params(input_dev, ABS_X, 0, 255, 0, 0);
+		input_set_abs_params(input_dev, ABS_Y, 0, 255, 0, 0);
+		break;
+	}
+
+	err = input_register_device(elo->dev);
+	if (err)
+		goto fail3;
+
+	return 0;
+
+ fail3: serio_close(serio);
+ fail2:	serio_set_drvdata(serio, NULL);
+ fail1:	input_free_device(input_dev);
+	kfree(elo);
+	return err;
+}
+
+/*
+ * The serio driver structure.
+ */
+
+static const struct serio_device_id elo_serio_ids[] = {
+	{
+		.type	= SERIO_RS232,
+		.proto	= SERIO_ELO,
+		.id	= SERIO_ANY,
+		.extra	= SERIO_ANY,
+	},
+	{ 0 }
+};
+
+MODULE_DEVICE_TABLE(serio, elo_serio_ids);
+
+static struct serio_driver elo_drv = {
+	.driver		= {
+		.name	= "elo",
+	},
+	.description	= DRIVER_DESC,
+	.id_table	= elo_serio_ids,
+	.interrupt	= elo_interrupt,
+	.connect	= elo_connect,
+	.disconnect	= elo_disconnect,
+};
+
+module_serio_driver(elo_drv);