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, 60 insertions, 0 deletions

diff --git a/drivers/hid/hid-xinmo.c b/drivers/hid/hid-xinmo.c
new file mode 100644
index 000000000..66b8bfb6e
--- /dev/null
+++ b/drivers/hid/hid-xinmo.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for Xin-Mo devices, currently only the Dual Arcade controller.
+ *  Fixes the negative axis event values (the devices sends -2) to match the
+ *  logical axis minimum of the HID report descriptor (the report announces
+ *  -1). It is needed because hid-input discards out of bounds values.
+ *  (This module is based on "hid-saitek" and "hid-lg".)
+ *
+ *  Copyright (c) 2013 Olivier Scherler
+ */
+
+/*
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+
+#include "hid-ids.h"
+
+/*
+ * Fix negative events that are out of bounds.
+ */
+static int xinmo_event(struct hid_device *hdev, struct hid_field *field,
+		struct hid_usage *usage, __s32 value)
+{
+	switch (usage->code) {
+	case ABS_X:
+	case ABS_Y:
+	case ABS_Z:
+	case ABS_RX:
+		if (value < -1) {
+			input_event(field->hidinput->input, usage->type,
+				usage->code, -1);
+			return 1;
+		}
+		break;
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id xinmo_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_XIN_MO, USB_DEVICE_ID_XIN_MO_DUAL_ARCADE) },
+	{ HID_USB_DEVICE(USB_VENDOR_ID_XIN_MO, USB_DEVICE_ID_THT_2P_ARCADE) },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(hid, xinmo_devices);
+
+static struct hid_driver xinmo_driver = {
+	.name = "xinmo",
+	.id_table = xinmo_devices,
+	.event = xinmo_event
+};
+
+module_hid_driver(xinmo_driver);
+MODULE_DESCRIPTION("HID driver for Xin-Mo devices");
+MODULE_LICENSE("GPL");