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, 205 insertions, 0 deletions

diff --git a/drivers/input/joystick/magellan.c b/drivers/input/joystick/magellan.c
new file mode 100644
index 000000000..201a049c8
--- /dev/null
+++ b/drivers/input/joystick/magellan.c
@@ -0,0 +1,205 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  Copyright (c) 1999-2001 Vojtech Pavlik
+ */
+
+/*
+ * Magellan and Space Mouse 6dof controller driver for Linux
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/serio.h>
+
+#define DRIVER_DESC	"Magellan and SpaceMouse 6dof controller driver"
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL");
+
+/*
+ * Definitions & global arrays.
+ */
+
+#define	MAGELLAN_MAX_LENGTH	32
+
+static int magellan_buttons[] = { BTN_0, BTN_1, BTN_2, BTN_3, BTN_4, BTN_5, BTN_6, BTN_7, BTN_8 };
+static int magellan_axes[] = { ABS_X, ABS_Y, ABS_Z, ABS_RX, ABS_RY, ABS_RZ };
+
+/*
+ * Per-Magellan data.
+ */
+
+struct magellan {
+	struct input_dev *dev;
+	int idx;
+	unsigned char data[MAGELLAN_MAX_LENGTH];
+	char phys[32];
+};
+
+/*
+ * magellan_crunch_nibbles() verifies that the bytes sent from the Magellan
+ * have correct upper nibbles for the lower ones, if not, the packet will
+ * be thrown away. It also strips these upper halves to simplify further
+ * processing.
+ */
+
+static int magellan_crunch_nibbles(unsigned char *data, int count)
+{
+	static const unsigned char nibbles[16] __nonstring = "0AB3D56GH9:K<MN?";
+
+	do {
+		if (data[count] == nibbles[data[count] & 0xf])
+			data[count] = data[count] & 0xf;
+		else
+			return -1;
+	} while (--count);
+
+	return 0;
+}
+
+static void magellan_process_packet(struct magellan* magellan)
+{
+	struct input_dev *dev = magellan->dev;
+	unsigned char *data = magellan->data;
+	int i, t;
+
+	if (!magellan->idx) return;
+
+	switch (magellan->data[0]) {
+
+		case 'd':				/* Axis data */
+			if (magellan->idx != 25) return;
+			if (magellan_crunch_nibbles(data, 24)) return;
+			for (i = 0; i < 6; i++)
+				input_report_abs(dev, magellan_axes[i],
+					(data[(i << 2) + 1] << 12 | data[(i << 2) + 2] << 8 |
+					 data[(i << 2) + 3] <<  4 | data[(i << 2) + 4]) - 32768);
+			break;
+
+		case 'k':				/* Button data */
+			if (magellan->idx != 4) return;
+			if (magellan_crunch_nibbles(data, 3)) return;
+			t = (data[1] << 1) | (data[2] << 5) | data[3];
+			for (i = 0; i < 9; i++) input_report_key(dev, magellan_buttons[i], (t >> i) & 1);
+			break;
+	}
+
+	input_sync(dev);
+}
+
+static irqreturn_t magellan_interrupt(struct serio *serio,
+		unsigned char data, unsigned int flags)
+{
+	struct magellan* magellan = serio_get_drvdata(serio);
+
+	if (data == '\r') {
+		magellan_process_packet(magellan);
+		magellan->idx = 0;
+	} else {
+		if (magellan->idx < MAGELLAN_MAX_LENGTH)
+			magellan->data[magellan->idx++] = data;
+	}
+	return IRQ_HANDLED;
+}
+
+/*
+ * magellan_disconnect() is the opposite of magellan_connect()
+ */
+
+static void magellan_disconnect(struct serio *serio)
+{
+	struct magellan* magellan = serio_get_drvdata(serio);
+
+	serio_close(serio);
+	serio_set_drvdata(serio, NULL);
+	input_unregister_device(magellan->dev);
+	kfree(magellan);
+}
+
+/*
+ * magellan_connect() is the routine that is called when someone adds a
+ * new serio device that supports Magellan protocol and registers it as
+ * an input device.
+ */
+
+static int magellan_connect(struct serio *serio, struct serio_driver *drv)
+{
+	struct magellan *magellan;
+	struct input_dev *input_dev;
+	int err = -ENOMEM;
+	int i;
+
+	magellan = kzalloc_obj(*magellan);
+	input_dev = input_allocate_device();
+	if (!magellan || !input_dev)
+		goto fail1;
+
+	magellan->dev = input_dev;
+	snprintf(magellan->phys, sizeof(magellan->phys), "%s/input0", serio->phys);
+
+	input_dev->name = "LogiCad3D Magellan / SpaceMouse";
+	input_dev->phys = magellan->phys;
+	input_dev->id.bustype = BUS_RS232;
+	input_dev->id.vendor = SERIO_MAGELLAN;
+	input_dev->id.product = 0x0001;
+	input_dev->id.version = 0x0100;
+	input_dev->dev.parent = &serio->dev;
+
+	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
+
+	for (i = 0; i < 9; i++)
+		set_bit(magellan_buttons[i], input_dev->keybit);
+
+	for (i = 0; i < 6; i++)
+		input_set_abs_params(input_dev, magellan_axes[i], -360, 360, 0, 0);
+
+	serio_set_drvdata(serio, magellan);
+
+	err = serio_open(serio, drv);
+	if (err)
+		goto fail2;
+
+	err = input_register_device(magellan->dev);
+	if (err)
+		goto fail3;
+
+	return 0;
+
+ fail3:	serio_close(serio);
+ fail2:	serio_set_drvdata(serio, NULL);
+ fail1:	input_free_device(input_dev);
+	kfree(magellan);
+	return err;
+}
+
+/*
+ * The serio driver structure.
+ */
+
+static const struct serio_device_id magellan_serio_ids[] = {
+	{
+		.type	= SERIO_RS232,
+		.proto	= SERIO_MAGELLAN,
+		.id	= SERIO_ANY,
+		.extra	= SERIO_ANY,
+	},
+	{ 0 }
+};
+
+MODULE_DEVICE_TABLE(serio, magellan_serio_ids);
+
+static struct serio_driver magellan_drv = {
+	.driver		= {
+		.name	= "magellan",
+	},
+	.description	= DRIVER_DESC,
+	.id_table	= magellan_serio_ids,
+	.interrupt	= magellan_interrupt,
+	.connect	= magellan_connect,
+	.disconnect	= magellan_disconnect,
+};
+
+module_serio_driver(magellan_drv);