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, 208 insertions, 0 deletions

diff --git a/drivers/hid/hid-saitek.c b/drivers/hid/hid-saitek.c
new file mode 100644
index 000000000..6fe7c087c
--- /dev/null
+++ b/drivers/hid/hid-saitek.c
@@ -0,0 +1,208 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for Saitek devices.
+ *
+ *  PS1000 (USB gamepad):
+ *  Fixes the HID report descriptor by removing a non-existent axis and
+ *  clearing the constant bit on the input reports for buttons and d-pad.
+ *  (This module is based on "hid-ortek".)
+ *  Copyright (c) 2012 Andreas Hübner
+ *
+ *  R.A.T.7, R.A.T.9, M.M.O.7 (USB gaming mice):
+ *  Fixes the mode button which cycles through three constantly pressed
+ *  buttons. All three press events are mapped to one button and the
+ *  missing release event is generated immediately.
+ */
+
+/*
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+
+#include "hid-ids.h"
+
+#define SAITEK_FIX_PS1000	0x0001
+#define SAITEK_RELEASE_MODE_RAT7	0x0002
+#define SAITEK_RELEASE_MODE_MMO7	0x0004
+
+struct saitek_sc {
+	unsigned long quirks;
+	int mode;
+};
+
+static int saitek_probe(struct hid_device *hdev,
+		const struct hid_device_id *id)
+{
+	unsigned long quirks = id->driver_data;
+	struct saitek_sc *ssc;
+	int ret;
+
+	ssc = devm_kzalloc(&hdev->dev, sizeof(*ssc), GFP_KERNEL);
+	if (ssc == NULL) {
+		hid_err(hdev, "can't alloc saitek descriptor\n");
+		return -ENOMEM;
+	}
+
+	ssc->quirks = quirks;
+	ssc->mode = -1;
+
+	hid_set_drvdata(hdev, ssc);
+
+	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 __u8 *saitek_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+		unsigned int *rsize)
+{
+	struct saitek_sc *ssc = hid_get_drvdata(hdev);
+
+	if ((ssc->quirks & SAITEK_FIX_PS1000) && *rsize == 137 &&
+			rdesc[20] == 0x09 && rdesc[21] == 0x33 &&
+			rdesc[94] == 0x81 && rdesc[95] == 0x03 &&
+			rdesc[110] == 0x81 && rdesc[111] == 0x03) {
+
+		hid_info(hdev, "Fixing up Saitek PS1000 report descriptor\n");
+
+		/* convert spurious axis to a "noop" Logical Minimum (0) */
+		rdesc[20] = 0x15;
+		rdesc[21] = 0x00;
+
+		/* clear constant bit on buttons and d-pad */
+		rdesc[95] = 0x02;
+		rdesc[111] = 0x02;
+
+	}
+	return rdesc;
+}
+
+static int saitek_raw_event(struct hid_device *hdev,
+		struct hid_report *report, u8 *raw_data, int size)
+{
+	struct saitek_sc *ssc = hid_get_drvdata(hdev);
+
+	if (ssc->quirks & SAITEK_RELEASE_MODE_RAT7 && size == 7) {
+		/* R.A.T.7 uses bits 13, 14, 15 for the mode */
+		int mode = -1;
+		if (raw_data[1] & 0x01)
+			mode = 0;
+		else if (raw_data[1] & 0x02)
+			mode = 1;
+		else if (raw_data[1] & 0x04)
+			mode = 2;
+
+		/* clear mode bits */
+		raw_data[1] &= ~0x07;
+
+		if (mode != ssc->mode) {
+			hid_dbg(hdev, "entered mode %d\n", mode);
+			if (ssc->mode != -1) {
+				/* use bit 13 as the mode button */
+				raw_data[1] |= 0x04;
+			}
+			ssc->mode = mode;
+		}
+	} else if (ssc->quirks & SAITEK_RELEASE_MODE_MMO7 && size == 8) {
+
+		/* M.M.O.7 uses bits 8, 22, 23 for the mode */
+		int mode = -1;
+		if (raw_data[1] & 0x80)
+			mode = 0;
+		else if (raw_data[2] & 0x01)
+			mode = 1;
+		else if (raw_data[2] & 0x02)
+			mode = 2;
+
+		/* clear mode bits */
+		raw_data[1] &= ~0x80;
+		raw_data[2] &= ~0x03;
+
+		if (mode != ssc->mode) {
+			hid_dbg(hdev, "entered mode %d\n", mode);
+			if (ssc->mode != -1) {
+				/* use bit 8 as the mode button, bits 22
+				 * and 23 do not represent buttons
+				 * according to the HID report descriptor
+				 */
+				raw_data[1] |= 0x80;
+			}
+			ssc->mode = mode;
+		}
+	}
+
+	return 0;
+}
+
+static int saitek_event(struct hid_device *hdev, struct hid_field *field,
+		struct hid_usage *usage, __s32 value)
+{
+	struct saitek_sc *ssc = hid_get_drvdata(hdev);
+	struct input_dev *input = field->hidinput->input;
+
+	if (usage->type == EV_KEY && value &&
+			(((ssc->quirks & SAITEK_RELEASE_MODE_RAT7) &&
+			  usage->code - BTN_MOUSE == 10) ||
+			((ssc->quirks & SAITEK_RELEASE_MODE_MMO7) &&
+			 usage->code - BTN_MOUSE == 15))) {
+
+		input_report_key(input, usage->code, 1);
+
+		/* report missing release event */
+		input_report_key(input, usage->code, 0);
+
+		return 1;
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id saitek_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_SAITEK, USB_DEVICE_ID_SAITEK_PS1000),
+		.driver_data = SAITEK_FIX_PS1000 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_MADCATZ, USB_DEVICE_ID_MADCATZ_RAT5),
+		.driver_data = SAITEK_RELEASE_MODE_RAT7 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_SAITEK, USB_DEVICE_ID_SAITEK_RAT7_OLD),
+		.driver_data = SAITEK_RELEASE_MODE_RAT7 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_SAITEK, USB_DEVICE_ID_SAITEK_RAT7),
+		.driver_data = SAITEK_RELEASE_MODE_RAT7 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_SAITEK, USB_DEVICE_ID_SAITEK_RAT7_CONTAGION),
+		.driver_data = SAITEK_RELEASE_MODE_RAT7 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_SAITEK, USB_DEVICE_ID_SAITEK_RAT9),
+		.driver_data = SAITEK_RELEASE_MODE_RAT7 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_MADCATZ, USB_DEVICE_ID_MADCATZ_RAT9),
+		.driver_data = SAITEK_RELEASE_MODE_RAT7 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_SAITEK, USB_DEVICE_ID_SAITEK_MMO7),
+		.driver_data = SAITEK_RELEASE_MODE_MMO7 },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_MADCATZ, USB_DEVICE_ID_MADCATZ_MMO7),
+		.driver_data = SAITEK_RELEASE_MODE_MMO7 },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(hid, saitek_devices);
+
+static struct hid_driver saitek_driver = {
+	.name = "saitek",
+	.id_table = saitek_devices,
+	.probe = saitek_probe,
+	.report_fixup = saitek_report_fixup,
+	.raw_event = saitek_raw_event,
+	.event = saitek_event,
+};
+module_hid_driver(saitek_driver);
+
+MODULE_DESCRIPTION("HID driver for Saitek devices.");
+MODULE_LICENSE("GPL");