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, 165 insertions, 0 deletions

diff --git a/drivers/input/keyboard/ipaq-micro-keys.c b/drivers/input/keyboard/ipaq-micro-keys.c
new file mode 100644
index 000000000..ebd991de7
--- /dev/null
+++ b/drivers/input/keyboard/ipaq-micro-keys.c
@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * h3600 atmel micro companion support, key subdevice
+ * based on previous kernel 2.4 version
+ * Author : Alessandro Gardich <gremlin@gremlin.it>
+ * Author : Linus Walleij <linus.walleij@linaro.org>
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/fs.h>
+#include <linux/interrupt.h>
+#include <linux/sched.h>
+#include <linux/pm.h>
+#include <linux/sysctl.h>
+#include <linux/proc_fs.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/input.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/ipaq-micro.h>
+
+static const u16 micro_keycodes[] = {
+	KEY_RECORD,		/* 1:  Record button			*/
+	KEY_CALENDAR,		/* 2:  Calendar				*/
+	KEY_ADDRESSBOOK,	/* 3:  Contacts (looks like Outlook)	*/
+	KEY_MAIL,		/* 4:  Envelope (Q on older iPAQs)	*/
+	KEY_HOMEPAGE,		/* 5:  Start (looks like swoopy arrow)	*/
+	KEY_UP,			/* 6:  Up				*/
+	KEY_RIGHT,		/* 7:  Right				*/
+	KEY_LEFT,		/* 8:  Left				*/
+	KEY_DOWN,		/* 9:  Down				*/
+};
+
+struct ipaq_micro_keys {
+	struct ipaq_micro *micro;
+	struct input_dev *input;
+	u16 codes[ARRAY_SIZE(micro_keycodes)];
+};
+
+static void micro_key_receive(void *data, int len, unsigned char *msg)
+{
+	struct ipaq_micro_keys *keys = data;
+	int key, down;
+
+	if (len < 1)
+		return;
+
+	down = 0x80 & msg[0];
+	key  = 0x7f & msg[0];
+
+	if (key < ARRAY_SIZE(micro_keycodes)) {
+		input_report_key(keys->input, keys->codes[key], down);
+		input_sync(keys->input);
+	}
+}
+
+static void micro_key_start(struct ipaq_micro_keys *keys)
+{
+	guard(spinlock_irq)(&keys->micro->lock);
+
+	keys->micro->key = micro_key_receive;
+	keys->micro->key_data = keys;
+}
+
+static void micro_key_stop(struct ipaq_micro_keys *keys)
+{
+	guard(spinlock_irq)(&keys->micro->lock);
+
+	keys->micro->key = NULL;
+	keys->micro->key_data = NULL;
+}
+
+static int micro_key_open(struct input_dev *input)
+{
+	struct ipaq_micro_keys *keys = input_get_drvdata(input);
+
+	micro_key_start(keys);
+
+	return 0;
+}
+
+static void micro_key_close(struct input_dev *input)
+{
+	struct ipaq_micro_keys *keys = input_get_drvdata(input);
+
+	micro_key_stop(keys);
+}
+
+static int micro_key_probe(struct platform_device *pdev)
+{
+	struct ipaq_micro_keys *keys;
+	int error;
+	int i;
+
+	keys = devm_kzalloc(&pdev->dev, sizeof(*keys), GFP_KERNEL);
+	if (!keys)
+		return -ENOMEM;
+
+	keys->micro = dev_get_drvdata(pdev->dev.parent);
+
+	keys->input = devm_input_allocate_device(&pdev->dev);
+	if (!keys->input)
+		return -ENOMEM;
+
+	keys->input->keycodesize = sizeof(micro_keycodes[0]);
+	keys->input->keycodemax = ARRAY_SIZE(micro_keycodes);
+	memcpy(keys->codes, micro_keycodes, sizeof(keys->codes));
+
+	keys->input->keycode = keys->codes;
+
+	__set_bit(EV_KEY, keys->input->evbit);
+	for (i = 0; i < ARRAY_SIZE(micro_keycodes); i++)
+		__set_bit(micro_keycodes[i], keys->input->keybit);
+
+	keys->input->name = "h3600 micro keys";
+	keys->input->open = micro_key_open;
+	keys->input->close = micro_key_close;
+	input_set_drvdata(keys->input, keys);
+
+	error = input_register_device(keys->input);
+	if (error)
+		return error;
+
+	platform_set_drvdata(pdev, keys);
+	return 0;
+}
+
+static int micro_key_suspend(struct device *dev)
+{
+	struct ipaq_micro_keys *keys = dev_get_drvdata(dev);
+
+	micro_key_stop(keys);
+
+	return 0;
+}
+
+static int micro_key_resume(struct device *dev)
+{
+	struct ipaq_micro_keys *keys = dev_get_drvdata(dev);
+	struct input_dev *input = keys->input;
+
+	guard(mutex)(&input->mutex);
+
+	if (input_device_enabled(input))
+		micro_key_start(keys);
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(micro_key_dev_pm_ops,
+				micro_key_suspend, micro_key_resume);
+
+static struct platform_driver micro_key_device_driver = {
+	.driver = {
+		.name    = "ipaq-micro-keys",
+		.pm	= pm_sleep_ptr(&micro_key_dev_pm_ops),
+	},
+	.probe   = micro_key_probe,
+};
+module_platform_driver(micro_key_device_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("driver for iPAQ Atmel micro keys");
+MODULE_ALIAS("platform:ipaq-micro-keys");