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, 98 insertions, 0 deletions

diff --git a/drivers/hid/hid-generic.c b/drivers/hid/hid-generic.c
new file mode 100644
index 000000000..c2de91674
--- /dev/null
+++ b/drivers/hid/hid-generic.c
@@ -0,0 +1,98 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  HID support for Linux
+ *
+ *  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) 2007-2008 Oliver Neukum
+ *  Copyright (c) 2006-2012 Jiri Kosina
+ *  Copyright (c) 2012 Henrik Rydberg
+ */
+
+/*
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/unaligned.h>
+#include <asm/byteorder.h>
+
+#include <linux/hid.h>
+
+static struct hid_driver hid_generic;
+
+static int __check_hid_generic(struct device_driver *drv, void *data)
+{
+	struct hid_driver *hdrv = to_hid_driver(drv);
+	struct hid_device *hdev = data;
+
+	if (hdrv == &hid_generic)
+		return 0;
+
+	return hid_match_device(hdev, hdrv) != NULL;
+}
+
+static bool hid_generic_match(struct hid_device *hdev,
+			      bool ignore_special_driver)
+{
+	if (ignore_special_driver)
+		return true;
+
+	if (hdev->quirks & HID_QUIRK_IGNORE_SPECIAL_DRIVER)
+		return true;
+
+	if (hdev->quirks & HID_QUIRK_HAVE_SPECIAL_DRIVER)
+		return false;
+
+	/*
+	 * If any other driver wants the device, leave the device to this other
+	 * driver.
+	 */
+	if (bus_for_each_drv(&hid_bus_type, NULL, hdev, __check_hid_generic))
+		return false;
+
+	return true;
+}
+
+static int hid_generic_probe(struct hid_device *hdev,
+			     const struct hid_device_id *id)
+{
+	int ret;
+
+	hdev->quirks |= HID_QUIRK_INPUT_PER_APP;
+
+	ret = hid_parse(hdev);
+	if (ret)
+		return ret;
+
+	return hid_hw_start(hdev, HID_CONNECT_DEFAULT);
+}
+
+static int hid_generic_reset_resume(struct hid_device *hdev)
+{
+	if (hdev->claimed & HID_CLAIMED_INPUT)
+		hidinput_reset_resume(hdev);
+
+	return 0;
+}
+
+static const struct hid_device_id hid_table[] = {
+	{ HID_DEVICE(HID_BUS_ANY, HID_GROUP_ANY, HID_ANY_ID, HID_ANY_ID) },
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, hid_table);
+
+static struct hid_driver hid_generic = {
+	.name = "hid-generic",
+	.id_table = hid_table,
+	.match = hid_generic_match,
+	.probe = hid_generic_probe,
+	.reset_resume = hid_generic_reset_resume,
+};
+module_hid_driver(hid_generic);
+
+MODULE_AUTHOR("Henrik Rydberg");
+MODULE_DESCRIPTION("HID generic driver");
+MODULE_LICENSE("GPL");