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, 184 insertions, 0 deletions

diff --git a/drivers/hid/hid-holtek-kbd.c b/drivers/hid/hid-holtek-kbd.c
new file mode 100644
index 000000000..d13543517
--- /dev/null
+++ b/drivers/hid/hid-holtek-kbd.c
@@ -0,0 +1,184 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * HID driver for Holtek keyboard
+ * Copyright (c) 2012 Tom Harwood
+*/
+
+/*
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include <linux/usb.h>
+
+#include "hid-ids.h"
+#include "usbhid/usbhid.h"
+
+/* Holtek based keyboards (USB ID 04d9:a055) have the following issues:
+ * - The report descriptor specifies an excessively large number of consumer
+ *   usages (2^15), which is more than HID_MAX_USAGES. This prevents proper
+ *   parsing of the report descriptor.
+ * - The report descriptor reports on caps/scroll/num lock key presses, but
+ *   doesn't have an LED output usage block.
+ *
+ * The replacement descriptor below fixes the number of consumer usages,
+ * and provides an LED output usage block. LED output events are redirected
+ * to the boot interface.
+ */
+
+static const __u8 holtek_kbd_rdesc_fixed[] = {
+	/* Original report descriptor, with reduced number of consumer usages */
+	0x05, 0x01,         /*  Usage Page (Desktop),                         */
+	0x09, 0x80,         /*  Usage (Sys Control),                          */
+	0xA1, 0x01,         /*  Collection (Application),                     */
+	0x85, 0x01,         /*      Report ID (1),                            */
+	0x19, 0x81,         /*      Usage Minimum (Sys Power Down),           */
+	0x29, 0x83,         /*      Usage Maximum (Sys Wake Up),              */
+	0x15, 0x00,         /*      Logical Minimum (0),                      */
+	0x25, 0x01,         /*      Logical Maximum (1),                      */
+	0x95, 0x03,         /*      Report Count (3),                         */
+	0x75, 0x01,         /*      Report Size (1),                          */
+	0x81, 0x02,         /*      Input (Variable),                         */
+	0x95, 0x01,         /*      Report Count (1),                         */
+	0x75, 0x05,         /*      Report Size (5),                          */
+	0x81, 0x01,         /*      Input (Constant),                         */
+	0xC0,               /*  End Collection,                               */
+	0x05, 0x0C,         /*  Usage Page (Consumer),                        */
+	0x09, 0x01,         /*  Usage (Consumer Control),                     */
+	0xA1, 0x01,         /*  Collection (Application),                     */
+	0x85, 0x02,         /*      Report ID (2),                            */
+	0x19, 0x00,         /*      Usage Minimum (00h),                      */
+	0x2A, 0xFF, 0x2F,   /*      Usage Maximum (0x2FFF), previously 0x7FFF */
+	0x15, 0x00,         /*      Logical Minimum (0),                      */
+	0x26, 0xFF, 0x2F,   /*      Logical Maximum (0x2FFF),previously 0x7FFF*/
+	0x95, 0x01,         /*      Report Count (1),                         */
+	0x75, 0x10,         /*      Report Size (16),                         */
+	0x81, 0x00,         /*      Input,                                    */
+	0xC0,               /*  End Collection,                               */
+	0x05, 0x01,         /*  Usage Page (Desktop),                         */
+	0x09, 0x06,         /*  Usage (Keyboard),                             */
+	0xA1, 0x01,         /*  Collection (Application),                     */
+	0x85, 0x03,         /*      Report ID (3),                            */
+	0x95, 0x38,         /*      Report Count (56),                        */
+	0x75, 0x01,         /*      Report Size (1),                          */
+	0x15, 0x00,         /*      Logical Minimum (0),                      */
+	0x25, 0x01,         /*      Logical Maximum (1),                      */
+	0x05, 0x07,         /*      Usage Page (Keyboard),                    */
+	0x19, 0xE0,         /*      Usage Minimum (KB Leftcontrol),           */
+	0x29, 0xE7,         /*      Usage Maximum (KB Right GUI),             */
+	0x19, 0x00,         /*      Usage Minimum (None),                     */
+	0x29, 0x2F,         /*      Usage Maximum (KB Lboxbracket And Lbrace),*/
+	0x81, 0x02,         /*      Input (Variable),                         */
+	0xC0,               /*  End Collection,                               */
+	0x05, 0x01,         /*  Usage Page (Desktop),                         */
+	0x09, 0x06,         /*  Usage (Keyboard),                             */
+	0xA1, 0x01,         /*  Collection (Application),                     */
+	0x85, 0x04,         /*      Report ID (4),                            */
+	0x95, 0x38,         /*      Report Count (56),                        */
+	0x75, 0x01,         /*      Report Size (1),                          */
+	0x15, 0x00,         /*      Logical Minimum (0),                      */
+	0x25, 0x01,         /*      Logical Maximum (1),                      */
+	0x05, 0x07,         /*      Usage Page (Keyboard),                    */
+	0x19, 0x30,         /*      Usage Minimum (KB Rboxbracket And Rbrace),*/
+	0x29, 0x67,         /*      Usage Maximum (KP Equals),                */
+	0x81, 0x02,         /*      Input (Variable),                         */
+	0xC0,               /*  End Collection                                */
+
+	/* LED usage for the boot protocol interface */
+	0x05, 0x01,         /*  Usage Page (Desktop),                         */
+	0x09, 0x06,         /*  Usage (Keyboard),                             */
+	0xA1, 0x01,         /*  Collection (Application),                     */
+	0x05, 0x08,         /*      Usage Page (LED),                         */
+	0x19, 0x01,         /*      Usage Minimum (01h),                      */
+	0x29, 0x03,         /*      Usage Maximum (03h),                      */
+	0x15, 0x00,         /*      Logical Minimum (0),                      */
+	0x25, 0x01,         /*      Logical Maximum (1),                      */
+	0x75, 0x01,         /*      Report Size (1),                          */
+	0x95, 0x03,         /*      Report Count (3),                         */
+	0x91, 0x02,         /*      Output (Variable),                        */
+	0x95, 0x05,         /*      Report Count (5),                         */
+	0x91, 0x01,         /*      Output (Constant),                        */
+	0xC0,               /*  End Collection                                */
+};
+
+static const __u8 *holtek_kbd_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+		unsigned int *rsize)
+{
+	struct usb_interface *intf = to_usb_interface(hdev->dev.parent);
+
+	if (intf->cur_altsetting->desc.bInterfaceNumber == 1) {
+		*rsize = sizeof(holtek_kbd_rdesc_fixed);
+		return holtek_kbd_rdesc_fixed;
+	}
+	return rdesc;
+}
+
+static int holtek_kbd_input_event(struct input_dev *dev, unsigned int type,
+		unsigned int code,
+		int value)
+{
+	struct hid_device *hid = input_get_drvdata(dev);
+	struct usb_device *usb_dev = hid_to_usb_dev(hid);
+
+	/* Locate the boot interface, to receive the LED change events */
+	struct usb_interface *boot_interface = usb_ifnum_to_if(usb_dev, 0);
+	struct hid_device *boot_hid;
+	struct hid_input *boot_hid_input;
+
+	if (unlikely(boot_interface == NULL))
+		return -ENODEV;
+
+	boot_hid = usb_get_intfdata(boot_interface);
+	if (list_empty(&boot_hid->inputs)) {
+		hid_err(hid, "no inputs found\n");
+		return -ENODEV;
+	}
+	boot_hid_input = list_first_entry(&boot_hid->inputs,
+		struct hid_input, list);
+
+	return boot_hid_input->input->event(boot_hid_input->input, type, code,
+			value);
+}
+
+static int holtek_kbd_probe(struct hid_device *hdev,
+		const struct hid_device_id *id)
+{
+	struct usb_interface *intf;
+	int ret;
+
+	if (!hid_is_usb(hdev))
+		return -EINVAL;
+
+	ret = hid_parse(hdev);
+	if (!ret)
+		ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+
+	intf = to_usb_interface(hdev->dev.parent);
+	if (!ret && intf->cur_altsetting->desc.bInterfaceNumber == 1) {
+		struct hid_input *hidinput;
+		list_for_each_entry(hidinput, &hdev->inputs, list) {
+			hidinput->input->event = holtek_kbd_input_event;
+		}
+	}
+
+	return ret;
+}
+
+static const struct hid_device_id holtek_kbd_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_HOLTEK_ALT,
+			USB_DEVICE_ID_HOLTEK_ALT_KEYBOARD) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, holtek_kbd_devices);
+
+static struct hid_driver holtek_kbd_driver = {
+	.name = "holtek_kbd",
+	.id_table = holtek_kbd_devices,
+	.report_fixup = holtek_kbd_report_fixup,
+	.probe = holtek_kbd_probe
+};
+module_hid_driver(holtek_kbd_driver);
+
+MODULE_DESCRIPTION("HID driver for Holtek keyboard");
+MODULE_LICENSE("GPL");