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, 217 insertions, 0 deletions

diff --git a/drivers/input/serio/pcips2.c b/drivers/input/serio/pcips2.c
new file mode 100644
index 000000000..78f47b0ca
--- /dev/null
+++ b/drivers/input/serio/pcips2.c
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * linux/drivers/input/serio/pcips2.c
+ *
+ *  Copyright (C) 2003 Russell King, All Rights Reserved.
+ *
+ *  I'm not sure if this is a generic PS/2 PCI interface or specific to
+ *  the Mobility Electronics docking station.
+ */
+#include <linux/module.h>
+#include <linux/interrupt.h>
+#include <linux/ioport.h>
+#include <linux/input.h>
+#include <linux/pci.h>
+#include <linux/slab.h>
+#include <linux/serio.h>
+#include <linux/delay.h>
+#include <asm/io.h>
+
+#define PS2_CTRL		(0)
+#define PS2_STATUS		(1)
+#define PS2_DATA		(2)
+
+#define PS2_CTRL_CLK		(1<<0)
+#define PS2_CTRL_DAT		(1<<1)
+#define PS2_CTRL_TXIRQ		(1<<2)
+#define PS2_CTRL_ENABLE		(1<<3)
+#define PS2_CTRL_RXIRQ		(1<<4)
+
+#define PS2_STAT_CLK		(1<<0)
+#define PS2_STAT_DAT		(1<<1)
+#define PS2_STAT_PARITY		(1<<2)
+#define PS2_STAT_RXFULL		(1<<5)
+#define PS2_STAT_TXBUSY		(1<<6)
+#define PS2_STAT_TXEMPTY	(1<<7)
+
+struct pcips2_data {
+	struct serio	*io;
+	unsigned int	base;
+	struct pci_dev	*dev;
+};
+
+static int pcips2_write(struct serio *io, unsigned char val)
+{
+	struct pcips2_data *ps2if = io->port_data;
+	unsigned int stat;
+
+	do {
+		stat = inb(ps2if->base + PS2_STATUS);
+		cpu_relax();
+	} while (!(stat & PS2_STAT_TXEMPTY));
+
+	outb(val, ps2if->base + PS2_DATA);
+
+	return 0;
+}
+
+static irqreturn_t pcips2_interrupt(int irq, void *devid)
+{
+	struct pcips2_data *ps2if = devid;
+	unsigned char status, scancode;
+	int handled = 0;
+
+	do {
+		unsigned int flag;
+
+		status = inb(ps2if->base + PS2_STATUS);
+		if (!(status & PS2_STAT_RXFULL))
+			break;
+		handled = 1;
+		scancode = inb(ps2if->base + PS2_DATA);
+		if (status == 0xff && scancode == 0xff)
+			break;
+
+		flag = (status & PS2_STAT_PARITY) ? 0 : SERIO_PARITY;
+
+		if (hweight8(scancode) & 1)
+			flag ^= SERIO_PARITY;
+
+		serio_interrupt(ps2if->io, scancode, flag);
+	} while (1);
+	return IRQ_RETVAL(handled);
+}
+
+static void pcips2_flush_input(struct pcips2_data *ps2if)
+{
+	unsigned char status, scancode;
+
+	do {
+		status = inb(ps2if->base + PS2_STATUS);
+		if (!(status & PS2_STAT_RXFULL))
+			break;
+		scancode = inb(ps2if->base + PS2_DATA);
+		if (status == 0xff && scancode == 0xff)
+			break;
+	} while (1);
+}
+
+static int pcips2_open(struct serio *io)
+{
+	struct pcips2_data *ps2if = io->port_data;
+	int ret, val = 0;
+
+	outb(PS2_CTRL_ENABLE, ps2if->base);
+	pcips2_flush_input(ps2if);
+
+	ret = request_irq(ps2if->dev->irq, pcips2_interrupt, IRQF_SHARED,
+			  "pcips2", ps2if);
+	if (ret == 0)
+		val = PS2_CTRL_ENABLE | PS2_CTRL_RXIRQ;
+
+	outb(val, ps2if->base);
+
+	return ret;
+}
+
+static void pcips2_close(struct serio *io)
+{
+	struct pcips2_data *ps2if = io->port_data;
+
+	outb(0, ps2if->base);
+
+	free_irq(ps2if->dev->irq, ps2if);
+}
+
+static int pcips2_probe(struct pci_dev *dev, const struct pci_device_id *id)
+{
+	struct pcips2_data *ps2if;
+	struct serio *serio;
+	int ret;
+
+	ret = pci_enable_device(dev);
+	if (ret)
+		goto out;
+
+	ret = pci_request_regions(dev, "pcips2");
+	if (ret)
+		goto disable;
+
+	ps2if = kzalloc_obj(*ps2if);
+	serio = kzalloc_obj(*serio);
+	if (!ps2if || !serio) {
+		ret = -ENOMEM;
+		goto release;
+	}
+
+
+	serio->id.type		= SERIO_8042;
+	serio->write		= pcips2_write;
+	serio->open		= pcips2_open;
+	serio->close		= pcips2_close;
+	strscpy(serio->name, pci_name(dev), sizeof(serio->name));
+	strscpy(serio->phys, dev_name(&dev->dev), sizeof(serio->phys));
+	serio->port_data	= ps2if;
+	serio->dev.parent	= &dev->dev;
+	ps2if->io		= serio;
+	ps2if->dev		= dev;
+	ps2if->base		= pci_resource_start(dev, 0);
+
+	pci_set_drvdata(dev, ps2if);
+
+	serio_register_port(ps2if->io);
+	return 0;
+
+ release:
+	kfree(ps2if);
+	kfree(serio);
+	pci_release_regions(dev);
+ disable:
+	pci_disable_device(dev);
+ out:
+	return ret;
+}
+
+static void pcips2_remove(struct pci_dev *dev)
+{
+	struct pcips2_data *ps2if = pci_get_drvdata(dev);
+
+	serio_unregister_port(ps2if->io);
+	kfree(ps2if);
+	pci_release_regions(dev);
+	pci_disable_device(dev);
+}
+
+static const struct pci_device_id pcips2_ids[] = {
+	{
+		.vendor		= 0x14f2,	/* MOBILITY */
+		.device		= 0x0123,	/* Keyboard */
+		.subvendor	= PCI_ANY_ID,
+		.subdevice	= PCI_ANY_ID,
+		.class		= PCI_CLASS_INPUT_KEYBOARD << 8,
+		.class_mask	= 0xffff00,
+	},
+	{
+		.vendor		= 0x14f2,	/* MOBILITY */
+		.device		= 0x0124,	/* Mouse */
+		.subvendor	= PCI_ANY_ID,
+		.subdevice	= PCI_ANY_ID,
+		.class		= PCI_CLASS_INPUT_MOUSE << 8,
+		.class_mask	= 0xffff00,
+	},
+	{ 0, }
+};
+MODULE_DEVICE_TABLE(pci, pcips2_ids);
+
+static struct pci_driver pcips2_driver = {
+	.name			= "pcips2",
+	.id_table		= pcips2_ids,
+	.probe			= pcips2_probe,
+	.remove			= pcips2_remove,
+};
+
+module_pci_driver(pcips2_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Russell King <rmk@arm.linux.org.uk>");
+MODULE_DESCRIPTION("PCI PS/2 keyboard/mouse driver");