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, 75 insertions, 0 deletions

diff --git a/drivers/hid/hid-rakk.c b/drivers/hid/hid-rakk.c
new file mode 100644
index 000000000..1140058a7
--- /dev/null
+++ b/drivers/hid/hid-rakk.c
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *  HID driver for Rakk devices
+ *
+ *  Copyright (c) 2026 Karl Cayme
+ *
+ *  The Rakk Dasig X gaming mouse has a faulty HID report descriptor that
+ *  declares USAGE_MAXIMUM = 3 (buttons 1-3) while actually sending 5 button
+ *  bits (REPORT_COUNT = 5). This causes the kernel to ignore side buttons
+ *  (buttons 4 and 5). This driver fixes the descriptor so all 5 buttons
+ *  are properly recognized across 3 modes (wired, dongle, and Bluetooth).
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include "hid-ids.h"
+
+/*
+ * The faulty byte is at offset 17 in the report descriptor for all three
+ * connection modes (USB direct, wireless dongle, and Bluetooth).
+ *
+ * Bytes 16-17 are: 0x29 0x03 (USAGE_MAXIMUM = 3)
+ * The fix changes byte 17 to 0x05 (USAGE_MAXIMUM = 5).
+ *
+ * Original descriptor bytes 0-17:
+ *   05 01 09 02 a1 01 85 01 09 01 a1 00 05 09 19 01 29 03
+ *                                                       ^^
+ *   Should be 0x05 to declare 5 buttons instead of 3.
+ */
+#define RAKK_RDESC_USAGE_MAX_OFFSET	17
+#define RAKK_RDESC_USAGE_MAX_ORIG	0x03
+#define RAKK_RDESC_USAGE_MAX_FIXED	0x05
+#define RAKK_RDESC_USB_SIZE		193
+#define RAKK_RDESC_DONGLE_SIZE		150
+#define RAKK_RDESC_BT_SIZE		89
+
+static const __u8 *rakk_report_fixup(struct hid_device *hdev, __u8 *rdesc,
+				     unsigned int *rsize)
+{
+	if (((*rsize == RAKK_RDESC_USB_SIZE &&
+	      hdev->product == USB_DEVICE_ID_TELINK_RAKK_DASIG_X) ||
+	     (*rsize == RAKK_RDESC_DONGLE_SIZE &&
+	      hdev->product == USB_DEVICE_ID_TELINK_RAKK_DASIG_X_DONGLE) ||
+	     (*rsize == RAKK_RDESC_BT_SIZE &&
+	      hdev->product == USB_DEVICE_ID_TELINK_RAKK_DASIG_X_BT)) &&
+	    rdesc[RAKK_RDESC_USAGE_MAX_OFFSET] == RAKK_RDESC_USAGE_MAX_ORIG) {
+		hid_info(hdev, "fixing Rakk Dasig X button count (3 -> 5)\n");
+		rdesc[RAKK_RDESC_USAGE_MAX_OFFSET] = RAKK_RDESC_USAGE_MAX_FIXED;
+	}
+
+	return rdesc;
+}
+
+static const struct hid_device_id rakk_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_TELINK,
+			 USB_DEVICE_ID_TELINK_RAKK_DASIG_X) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_TELINK,
+			 USB_DEVICE_ID_TELINK_RAKK_DASIG_X_DONGLE) },
+	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_TELINK,
+			       USB_DEVICE_ID_TELINK_RAKK_DASIG_X_BT) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, rakk_devices);
+
+static struct hid_driver rakk_driver = {
+	.name = "rakk",
+	.id_table = rakk_devices,
+	.report_fixup = rakk_report_fixup,
+};
+module_hid_driver(rakk_driver);
+
+MODULE_DESCRIPTION("HID driver for Rakk Dasig X mouse - fix side button support");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Karl Cayme");