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, 156 insertions, 0 deletions

diff --git a/drivers/hid/hid-lgff.c b/drivers/hid/hid-lgff.c
new file mode 100644
index 000000000..aed4ddc39
--- /dev/null
+++ b/drivers/hid/hid-lgff.c
@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Force feedback support for hid-compliant for some of the devices from
+ * Logitech, namely:
+ * - WingMan Cordless RumblePad
+ * - WingMan Force 3D
+ *
+ *  Copyright (c) 2002-2004 Johann Deneux
+ *  Copyright (c) 2006 Anssi Hannula <anssi.hannula@gmail.com>
+ */
+
+/*
+ *
+ * Should you need to contact me, the author, you can do so by
+ * e-mail - mail your message to <johann.deneux@it.uu.se>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/input.h>
+#include <linux/hid.h>
+
+#include "hid-lg.h"
+
+struct dev_type {
+	u16 idVendor;
+	u16 idProduct;
+	const signed short *ff;
+};
+
+static const signed short ff_rumble[] = {
+	FF_RUMBLE,
+	-1
+};
+
+static const signed short ff_joystick[] = {
+	FF_CONSTANT,
+	-1
+};
+
+static const signed short ff_joystick_ac[] = {
+	FF_CONSTANT,
+	FF_AUTOCENTER,
+	-1
+};
+
+static const struct dev_type devices[] = {
+	{ 0x046d, 0xc211, ff_rumble },
+	{ 0x046d, 0xc219, ff_rumble },
+	{ 0x046d, 0xc283, ff_joystick },
+	{ 0x046d, 0xc286, ff_joystick_ac },
+	{ 0x046d, 0xc287, ff_joystick_ac },
+	{ 0x046d, 0xc293, ff_joystick },
+	{ 0x046d, 0xc295, ff_joystick },
+};
+
+static int hid_lgff_play(struct input_dev *dev, void *data, struct ff_effect *effect)
+{
+	struct hid_device *hid = input_get_drvdata(dev);
+	struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
+	struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
+	int x, y;
+	unsigned int left, right;
+
+#define CLAMP(x) if (x < 0) x = 0; if (x > 0xff) x = 0xff
+
+	switch (effect->type) {
+	case FF_CONSTANT:
+		x = effect->u.ramp.start_level + 0x7f;	/* 0x7f is center */
+		y = effect->u.ramp.end_level + 0x7f;
+		CLAMP(x);
+		CLAMP(y);
+		report->field[0]->value[0] = 0x51;
+		report->field[0]->value[1] = 0x08;
+		report->field[0]->value[2] = x;
+		report->field[0]->value[3] = y;
+		dbg_hid("(x, y)=(%04x, %04x)\n", x, y);
+		hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+		break;
+
+	case FF_RUMBLE:
+		right = effect->u.rumble.strong_magnitude;
+		left = effect->u.rumble.weak_magnitude;
+		right = right * 0xff / 0xffff;
+		left = left * 0xff / 0xffff;
+		CLAMP(left);
+		CLAMP(right);
+		report->field[0]->value[0] = 0x42;
+		report->field[0]->value[1] = 0x00;
+		report->field[0]->value[2] = left;
+		report->field[0]->value[3] = right;
+		dbg_hid("(left, right)=(%04x, %04x)\n", left, right);
+		hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+		break;
+	}
+	return 0;
+}
+
+static void hid_lgff_set_autocenter(struct input_dev *dev, u16 magnitude)
+{
+	struct hid_device *hid = input_get_drvdata(dev);
+	struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
+	struct hid_report *report = list_entry(report_list->next, struct hid_report, list);
+	__s32 *value = report->field[0]->value;
+	magnitude = (magnitude >> 12) & 0xf;
+	*value++ = 0xfe;
+	*value++ = 0x0d;
+	*value++ = magnitude;   /* clockwise strength */
+	*value++ = magnitude;   /* counter-clockwise strength */
+	*value++ = 0x80;
+	*value++ = 0x00;
+	*value = 0x00;
+	hid_hw_request(hid, report, HID_REQ_SET_REPORT);
+}
+
+int lgff_init(struct hid_device* hid)
+{
+	struct hid_input *hidinput;
+	struct input_dev *dev;
+	const signed short *ff_bits = ff_joystick;
+	int error;
+	int i;
+
+	if (list_empty(&hid->inputs)) {
+		hid_err(hid, "no inputs found\n");
+		return -ENODEV;
+	}
+	hidinput = list_entry(hid->inputs.next, struct hid_input, list);
+	dev = hidinput->input;
+
+	/* Check that the report looks ok */
+	if (!hid_validate_values(hid, HID_OUTPUT_REPORT, 0, 0, 7))
+		return -ENODEV;
+
+	for (i = 0; i < ARRAY_SIZE(devices); i++) {
+		if (dev->id.vendor == devices[i].idVendor &&
+		    dev->id.product == devices[i].idProduct) {
+			ff_bits = devices[i].ff;
+			break;
+		}
+	}
+
+	for (i = 0; ff_bits[i] >= 0; i++)
+		set_bit(ff_bits[i], dev->ffbit);
+
+	error = input_ff_create_memless(dev, NULL, hid_lgff_play);
+	if (error)
+		return error;
+
+	if ( test_bit(FF_AUTOCENTER, dev->ffbit) )
+		dev->ff->set_autocenter = hid_lgff_set_autocenter;
+
+	pr_info("Force feedback for Logitech force feedback devices by Johann Deneux <johann.deneux@it.uu.se>\n");
+
+	return 0;
+}