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, 167 insertions, 0 deletions

diff --git a/drivers/hid/hid-a4tech.c b/drivers/hid/hid-a4tech.c
new file mode 100644
index 000000000..54bfaf611
--- /dev/null
+++ b/drivers/hid/hid-a4tech.c
@@ -0,0 +1,167 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for some a4tech "special" devices
+ *
+ *  Copyright (c) 1999 Andreas Gal
+ *  Copyright (c) 2000-2005 Vojtech Pavlik <vojtech@suse.cz>
+ *  Copyright (c) 2005 Michael Haboustak <mike-@cinci.rr.com> for Concept2, Inc
+ *  Copyright (c) 2006-2007 Jiri Kosina
+ *  Copyright (c) 2008 Jiri Slaby
+ */
+
+/*
+ */
+
+#include <linux/device.h>
+#include <linux/input.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#include "hid-ids.h"
+
+#define A4_2WHEEL_MOUSE_HACK_7	0x01
+#define A4_2WHEEL_MOUSE_HACK_B8	0x02
+
+#define A4_WHEEL_ORIENTATION	(HID_UP_GENDESK | 0x000000b8)
+
+struct a4tech_sc {
+	unsigned long quirks;
+	unsigned int hw_wheel;
+	__s32 delayed_value;
+};
+
+static int a4_input_mapping(struct hid_device *hdev, struct hid_input *hi,
+			    struct hid_field *field, struct hid_usage *usage,
+			    unsigned long **bit, int *max)
+{
+	struct a4tech_sc *a4 = hid_get_drvdata(hdev);
+
+	if (a4->quirks & A4_2WHEEL_MOUSE_HACK_B8 &&
+	    usage->hid == A4_WHEEL_ORIENTATION) {
+		/*
+		 * We do not want to have this usage mapped to anything as it's
+		 * nonstandard and doesn't really behave like an HID report.
+		 * It's only selecting the orientation (vertical/horizontal) of
+		 * the previous mouse wheel report. The input_events will be
+		 * generated once both reports are recorded in a4_event().
+		 */
+		return -1;
+	}
+
+	return 0;
+
+}
+
+static int a4_input_mapped(struct hid_device *hdev, struct hid_input *hi,
+		struct hid_field *field, struct hid_usage *usage,
+		unsigned long **bit, int *max)
+{
+	struct a4tech_sc *a4 = hid_get_drvdata(hdev);
+
+	if (usage->type == EV_REL && usage->code == REL_WHEEL_HI_RES) {
+		set_bit(REL_HWHEEL, *bit);
+		set_bit(REL_HWHEEL_HI_RES, *bit);
+	}
+
+	if ((a4->quirks & A4_2WHEEL_MOUSE_HACK_7) && usage->hid == 0x00090007)
+		return -1;
+
+	return 0;
+}
+
+static int a4_event(struct hid_device *hdev, struct hid_field *field,
+		struct hid_usage *usage, __s32 value)
+{
+	struct a4tech_sc *a4 = hid_get_drvdata(hdev);
+	struct input_dev *input;
+
+	if (!(hdev->claimed & HID_CLAIMED_INPUT) || !field->hidinput)
+		return 0;
+
+	input = field->hidinput->input;
+
+	if (a4->quirks & A4_2WHEEL_MOUSE_HACK_B8) {
+		if (usage->type == EV_REL && usage->code == REL_WHEEL_HI_RES) {
+			a4->delayed_value = value;
+			return 1;
+		}
+
+		if (usage->hid == A4_WHEEL_ORIENTATION) {
+			input_event(input, EV_REL, value ? REL_HWHEEL :
+					REL_WHEEL, a4->delayed_value);
+			input_event(input, EV_REL, value ? REL_HWHEEL_HI_RES :
+					REL_WHEEL_HI_RES, a4->delayed_value * 120);
+			return 1;
+		}
+	}
+
+	if ((a4->quirks & A4_2WHEEL_MOUSE_HACK_7) && usage->hid == 0x00090007) {
+		a4->hw_wheel = !!value;
+		return 1;
+	}
+
+	if (usage->code == REL_WHEEL_HI_RES && a4->hw_wheel) {
+		input_event(input, usage->type, REL_HWHEEL, value);
+		input_event(input, usage->type, REL_HWHEEL_HI_RES, value * 120);
+		return 1;
+	}
+
+	return 0;
+}
+
+static int a4_probe(struct hid_device *hdev, const struct hid_device_id *id)
+{
+	struct a4tech_sc *a4;
+	int ret;
+
+	a4 = devm_kzalloc(&hdev->dev, sizeof(*a4), GFP_KERNEL);
+	if (a4 == NULL) {
+		hid_err(hdev, "can't alloc device descriptor\n");
+		return -ENOMEM;
+	}
+
+	a4->quirks = id->driver_data;
+
+	hid_set_drvdata(hdev, a4);
+
+	ret = hid_parse(hdev);
+	if (ret) {
+		hid_err(hdev, "parse failed\n");
+		return ret;
+	}
+
+	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+	if (ret) {
+		hid_err(hdev, "hw start failed\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id a4_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_A4TECH, USB_DEVICE_ID_A4TECH_WCP32PU),
+		.driver_data = A4_2WHEEL_MOUSE_HACK_7 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_A4TECH, USB_DEVICE_ID_A4TECH_X5_005D),
+		.driver_data = A4_2WHEEL_MOUSE_HACK_B8 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_A4TECH, USB_DEVICE_ID_A4TECH_RP_649),
+		.driver_data = A4_2WHEEL_MOUSE_HACK_B8 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_A4TECH, USB_DEVICE_ID_A4TECH_NB_95),
+		.driver_data = A4_2WHEEL_MOUSE_HACK_B8 },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, a4_devices);
+
+static struct hid_driver a4_driver = {
+	.name = "a4tech",
+	.id_table = a4_devices,
+	.input_mapping = a4_input_mapping,
+	.input_mapped = a4_input_mapped,
+	.event = a4_event,
+	.probe = a4_probe,
+};
+module_hid_driver(a4_driver);
+
+MODULE_DESCRIPTION("HID driver for some a4tech \"special\" devices");
+MODULE_LICENSE("GPL");