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, 130 insertions, 0 deletions

diff --git a/drivers/input/misc/ab8500-ponkey.c b/drivers/input/misc/ab8500-ponkey.c
new file mode 100644
index 000000000..a9b901368
--- /dev/null
+++ b/drivers/input/misc/ab8500-ponkey.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) ST-Ericsson SA 2010
+ *
+ * Author: Sundar Iyer <sundar.iyer@stericsson.com> for ST-Ericsson
+ *
+ * AB8500 Power-On Key handler
+ */
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/abx500/ab8500.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+
+/**
+ * struct ab8500_ponkey - ab8500 ponkey information
+ * @idev: pointer to input device
+ * @ab8500: ab8500 parent
+ * @irq_dbf: irq number for falling transition
+ * @irq_dbr: irq number for rising transition
+ */
+struct ab8500_ponkey {
+	struct input_dev	*idev;
+	struct ab8500		*ab8500;
+	int			irq_dbf;
+	int			irq_dbr;
+};
+
+/* AB8500 gives us an interrupt when ONKEY is held */
+static irqreturn_t ab8500_ponkey_handler(int irq, void *data)
+{
+	struct ab8500_ponkey *ponkey = data;
+
+	if (irq == ponkey->irq_dbf)
+		input_report_key(ponkey->idev, KEY_POWER, true);
+	else if (irq == ponkey->irq_dbr)
+		input_report_key(ponkey->idev, KEY_POWER, false);
+
+	input_sync(ponkey->idev);
+
+	return IRQ_HANDLED;
+}
+
+static int ab8500_ponkey_probe(struct platform_device *pdev)
+{
+	struct ab8500 *ab8500 = dev_get_drvdata(pdev->dev.parent);
+	struct ab8500_ponkey *ponkey;
+	struct input_dev *input;
+	int irq_dbf, irq_dbr;
+	int error;
+
+	irq_dbf = platform_get_irq_byname(pdev, "ONKEY_DBF");
+	if (irq_dbf < 0)
+		return irq_dbf;
+
+	irq_dbr = platform_get_irq_byname(pdev, "ONKEY_DBR");
+	if (irq_dbr < 0)
+		return irq_dbr;
+
+	ponkey = devm_kzalloc(&pdev->dev, sizeof(struct ab8500_ponkey),
+			      GFP_KERNEL);
+	if (!ponkey)
+		return -ENOMEM;
+
+	input = devm_input_allocate_device(&pdev->dev);
+	if (!input)
+		return -ENOMEM;
+
+	ponkey->idev = input;
+	ponkey->ab8500 = ab8500;
+	ponkey->irq_dbf = irq_dbf;
+	ponkey->irq_dbr = irq_dbr;
+
+	input->name = "AB8500 POn(PowerOn) Key";
+	input->dev.parent = &pdev->dev;
+
+	input_set_capability(input, EV_KEY, KEY_POWER);
+
+	error = devm_request_any_context_irq(&pdev->dev, ponkey->irq_dbf,
+					     ab8500_ponkey_handler, 0,
+					     "ab8500-ponkey-dbf", ponkey);
+	if (error < 0) {
+		dev_err(ab8500->dev, "Failed to request dbf IRQ#%d: %d\n",
+			ponkey->irq_dbf, error);
+		return error;
+	}
+
+	error = devm_request_any_context_irq(&pdev->dev, ponkey->irq_dbr,
+					     ab8500_ponkey_handler, 0,
+					     "ab8500-ponkey-dbr", ponkey);
+	if (error < 0) {
+		dev_err(ab8500->dev, "Failed to request dbr IRQ#%d: %d\n",
+			ponkey->irq_dbr, error);
+		return error;
+	}
+
+	error = input_register_device(ponkey->idev);
+	if (error) {
+		dev_err(ab8500->dev, "Can't register input device: %d\n", error);
+		return error;
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id ab8500_ponkey_match[] = {
+	{ .compatible = "stericsson,ab8500-ponkey", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, ab8500_ponkey_match);
+#endif
+
+static struct platform_driver ab8500_ponkey_driver = {
+	.driver		= {
+		.name	= "ab8500-poweron-key",
+		.of_match_table = of_match_ptr(ab8500_ponkey_match),
+	},
+	.probe		= ab8500_ponkey_probe,
+};
+module_platform_driver(ab8500_ponkey_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Sundar Iyer <sundar.iyer@stericsson.com>");
+MODULE_DESCRIPTION("ST-Ericsson AB8500 Power-ON(Pon) Key driver");