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, 148 insertions, 0 deletions

diff --git a/drivers/input/misc/wm831x-on.c b/drivers/input/misc/wm831x-on.c
new file mode 100644
index 000000000..18eb319bc
--- /dev/null
+++ b/drivers/input/misc/wm831x-on.c
@@ -0,0 +1,148 @@
+/*
+ * wm831x-on.c - WM831X ON pin driver
+ *
+ * Copyright (C) 2009 Wolfson Microelectronics plc
+ *
+ * This file is subject to the terms and conditions of the GNU General
+ * Public License. See the file "COPYING" in the main directory of this
+ * archive for more details.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/workqueue.h>
+#include <linux/mfd/wm831x/core.h>
+
+struct wm831x_on {
+	struct input_dev *dev;
+	struct delayed_work work;
+	struct wm831x *wm831x;
+};
+
+/*
+ * The chip gives us an interrupt when the ON pin is asserted but we
+ * then need to poll to see when the pin is deasserted.
+ */
+static void wm831x_poll_on(struct work_struct *work)
+{
+	struct wm831x_on *wm831x_on = container_of(work, struct wm831x_on,
+						   work.work);
+	struct wm831x *wm831x = wm831x_on->wm831x;
+	int poll, ret;
+
+	ret = wm831x_reg_read(wm831x, WM831X_ON_PIN_CONTROL);
+	if (ret >= 0) {
+		poll = !(ret & WM831X_ON_PIN_STS);
+
+		input_report_key(wm831x_on->dev, KEY_POWER, poll);
+		input_sync(wm831x_on->dev);
+	} else {
+		dev_err(wm831x->dev, "Failed to read ON status: %d\n", ret);
+		poll = 1;
+	}
+
+	if (poll)
+		schedule_delayed_work(&wm831x_on->work, 100);
+}
+
+static irqreturn_t wm831x_on_irq(int irq, void *data)
+{
+	struct wm831x_on *wm831x_on = data;
+
+	schedule_delayed_work(&wm831x_on->work, 0);
+
+	return IRQ_HANDLED;
+}
+
+static int wm831x_on_probe(struct platform_device *pdev)
+{
+	struct wm831x *wm831x = dev_get_drvdata(pdev->dev.parent);
+	struct wm831x_on *wm831x_on;
+	int irq = wm831x_irq(wm831x, platform_get_irq(pdev, 0));
+	int ret;
+
+	wm831x_on = devm_kzalloc(&pdev->dev, sizeof(struct wm831x_on),
+				 GFP_KERNEL);
+	if (!wm831x_on) {
+		dev_err(&pdev->dev, "Can't allocate data\n");
+		return -ENOMEM;
+	}
+
+	wm831x_on->wm831x = wm831x;
+	INIT_DELAYED_WORK(&wm831x_on->work, wm831x_poll_on);
+
+	wm831x_on->dev = devm_input_allocate_device(&pdev->dev);
+	if (!wm831x_on->dev) {
+		dev_err(&pdev->dev, "Can't allocate input dev\n");
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	wm831x_on->dev->evbit[0] = BIT_MASK(EV_KEY);
+	wm831x_on->dev->keybit[BIT_WORD(KEY_POWER)] = BIT_MASK(KEY_POWER);
+	wm831x_on->dev->name = "wm831x_on";
+	wm831x_on->dev->phys = "wm831x_on/input0";
+	wm831x_on->dev->dev.parent = &pdev->dev;
+
+	ret = request_threaded_irq(irq, NULL, wm831x_on_irq,
+				   IRQF_TRIGGER_RISING | IRQF_ONESHOT,
+				   "wm831x_on",
+				   wm831x_on);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "Unable to request IRQ: %d\n", ret);
+		goto err_input_dev;
+	}
+	ret = input_register_device(wm831x_on->dev);
+	if (ret) {
+		dev_dbg(&pdev->dev, "Can't register input device: %d\n", ret);
+		goto err_irq;
+	}
+
+	platform_set_drvdata(pdev, wm831x_on);
+
+	return 0;
+
+err_irq:
+	free_irq(irq, wm831x_on);
+err_input_dev:
+err:
+	return ret;
+}
+
+static void wm831x_on_remove(struct platform_device *pdev)
+{
+	struct wm831x_on *wm831x_on = platform_get_drvdata(pdev);
+	int irq = platform_get_irq(pdev, 0);
+
+	free_irq(irq, wm831x_on);
+	cancel_delayed_work_sync(&wm831x_on->work);
+}
+
+static struct platform_driver wm831x_on_driver = {
+	.probe		= wm831x_on_probe,
+	.remove		= wm831x_on_remove,
+	.driver		= {
+		.name	= "wm831x-on",
+	},
+};
+module_platform_driver(wm831x_on_driver);
+
+MODULE_ALIAS("platform:wm831x-on");
+MODULE_DESCRIPTION("WM831x ON pin");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Mark Brown <broonie@opensource.wolfsonmicro.com>");
+