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, 79 insertions, 0 deletions

diff --git a/drivers/hid/hid-ezkey.c b/drivers/hid/hid-ezkey.c
new file mode 100644
index 000000000..0e28bc0b8
--- /dev/null
+++ b/drivers/hid/hid-ezkey.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID driver for some ezkey "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 "hid-ids.h"
+
+#define ez_map_rel(c)	hid_map_usage(hi, usage, bit, max, EV_REL, (c))
+#define ez_map_key(c)	hid_map_usage(hi, usage, bit, max, EV_KEY, (c))
+
+static int ez_input_mapping(struct hid_device *hdev, struct hid_input *hi,
+		struct hid_field *field, struct hid_usage *usage,
+		unsigned long **bit, int *max)
+{
+	if ((usage->hid & HID_USAGE_PAGE) != HID_UP_CONSUMER)
+		return 0;
+
+	switch (usage->hid & HID_USAGE) {
+	case 0x230: ez_map_key(BTN_MOUSE);	break;
+	case 0x231: ez_map_rel(REL_WHEEL);	break;
+	/*
+	 * this keyboard has a scrollwheel implemented in
+	 * totally broken way. We map this usage temporarily
+	 * to HWHEEL and handle it in the event quirk handler
+	 */
+	case 0x232: ez_map_rel(REL_HWHEEL);	break;
+	default:
+		return 0;
+	}
+	return 1;
+}
+
+static int ez_event(struct hid_device *hdev, struct hid_field *field,
+		struct hid_usage *usage, __s32 value)
+{
+	if (!(hdev->claimed & HID_CLAIMED_INPUT) || !field->hidinput ||
+			!usage->type)
+		return 0;
+
+	/* handle the temporary quirky mapping to HWHEEL */
+	if (usage->type == EV_REL && usage->code == REL_HWHEEL) {
+		struct input_dev *input = field->hidinput->input;
+		input_event(input, usage->type, REL_WHEEL, -value);
+		return 1;
+	}
+
+	return 0;
+}
+
+static const struct hid_device_id ez_devices[] = {
+	{ HID_USB_DEVICE(USB_VENDOR_ID_EZKEY, USB_DEVICE_ID_BTC_8193) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, ez_devices);
+
+static struct hid_driver ez_driver = {
+	.name = "ezkey",
+	.id_table = ez_devices,
+	.input_mapping = ez_input_mapping,
+	.event = ez_event,
+};
+module_hid_driver(ez_driver);
+
+MODULE_DESCRIPTION("HID driver for some ezkey \"special\" devices");
+MODULE_LICENSE("GPL");