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, 173 insertions, 0 deletions

diff --git a/drivers/mfd/88pm886.c b/drivers/mfd/88pm886.c
new file mode 100644
index 000000000..f8401d5e6
--- /dev/null
+++ b/drivers/mfd/88pm886.c
@@ -0,0 +1,173 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/i2c.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/regmap.h>
+
+#include <linux/mfd/88pm886.h>
+
+static const struct regmap_config pm886_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = PM886_REG_RTC_SPARE6,
+};
+
+static const struct regmap_config pm886_regmap_battery_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = PM886_REG_CLS_CONFIG1,
+};
+
+static const struct regmap_irq pm886_regmap_irqs[] = {
+	REGMAP_IRQ_REG(PM886_IRQ_ONKEY, 0, PM886_INT_ENA1_ONKEY),
+};
+
+static const struct regmap_irq_chip pm886_regmap_irq_chip = {
+	.name = "88pm886",
+	.irqs = pm886_regmap_irqs,
+	.num_irqs = ARRAY_SIZE(pm886_regmap_irqs),
+	.num_regs = 4,
+	.status_base = PM886_REG_INT_STATUS1,
+	.ack_base = PM886_REG_INT_STATUS1,
+	.unmask_base = PM886_REG_INT_ENA_1,
+};
+
+static const struct resource pm886_onkey_resources[] = {
+	DEFINE_RES_IRQ_NAMED(PM886_IRQ_ONKEY, "88pm886-onkey"),
+};
+
+static const struct mfd_cell pm886_devs[] = {
+	MFD_CELL_NAME("88pm886-gpadc"),
+	MFD_CELL_RES("88pm886-onkey", pm886_onkey_resources),
+	MFD_CELL_NAME("88pm886-regulator"),
+	MFD_CELL_NAME("88pm886-rtc"),
+};
+
+static int pm886_power_off_handler(struct sys_off_data *sys_off_data)
+{
+	struct pm886_chip *chip = sys_off_data->cb_data;
+	struct regmap *regmap = chip->regmap;
+	struct device *dev = &chip->client->dev;
+	int err;
+
+	err = regmap_update_bits(regmap, PM886_REG_MISC_CONFIG1, PM886_SW_PDOWN, PM886_SW_PDOWN);
+	if (err) {
+		dev_err(dev, "Failed to power off the device: %d\n", err);
+		return NOTIFY_BAD;
+	}
+	return NOTIFY_DONE;
+}
+
+static int pm886_setup_irq(struct pm886_chip *chip,
+		struct regmap_irq_chip_data **irq_data)
+{
+	struct regmap *regmap = chip->regmap;
+	struct device *dev = &chip->client->dev;
+	int err;
+
+	/* Set interrupt clearing mode to clear on write. */
+	err = regmap_update_bits(regmap, PM886_REG_MISC_CONFIG2,
+			PM886_INT_INV | PM886_INT_CLEAR | PM886_INT_MASK_MODE,
+			PM886_INT_WC);
+	if (err) {
+		dev_err(dev, "Failed to set interrupt clearing mode: %d\n", err);
+		return err;
+	}
+
+	err = devm_regmap_add_irq_chip(dev, regmap, chip->client->irq,
+					IRQF_ONESHOT, 0, &pm886_regmap_irq_chip,
+					irq_data);
+	if (err) {
+		dev_err(dev, "Failed to request IRQ: %d\n", err);
+		return err;
+	}
+
+	return 0;
+}
+
+static int pm886_probe(struct i2c_client *client)
+{
+	struct regmap *regmap, *regmap_battery;
+	struct regmap_irq_chip_data *irq_data;
+	struct device *dev = &client->dev;
+	struct i2c_client *battery_page;
+	struct pm886_chip *chip;
+	unsigned int chip_id;
+	int err;
+
+	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	chip->client = client;
+	chip->chip_id = (uintptr_t)device_get_match_data(dev);
+	i2c_set_clientdata(client, chip);
+
+	regmap = devm_regmap_init_i2c(client, &pm886_regmap_config);
+	if (IS_ERR(regmap))
+		return dev_err_probe(dev, PTR_ERR(regmap), "Failed to initialize regmap\n");
+	chip->regmap = regmap;
+
+	err = regmap_read(regmap, PM886_REG_ID, &chip_id);
+	if (err)
+		return dev_err_probe(dev, err, "Failed to read chip ID\n");
+
+	if (chip->chip_id != chip_id)
+		return dev_err_probe(dev, -EINVAL, "Unsupported chip: 0x%x\n", chip_id);
+
+	battery_page = devm_i2c_new_dummy_device(dev, client->adapter,
+						 client->addr + PM886_PAGE_OFFSET_BATTERY);
+	if (IS_ERR(battery_page))
+		return dev_err_probe(dev, PTR_ERR(battery_page),
+				     "Failed to initialize battery page\n");
+
+	regmap_battery = devm_regmap_init_i2c(battery_page, &pm886_regmap_battery_config);
+	if (IS_ERR(regmap_battery))
+		return dev_err_probe(dev, PTR_ERR(regmap_battery),
+				     "Failed to initialize battery regmap\n");
+	chip->regmap_battery = regmap_battery;
+
+	err = pm886_setup_irq(chip, &irq_data);
+	if (err)
+		return err;
+
+	err = devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE, pm886_devs, ARRAY_SIZE(pm886_devs),
+				NULL, 0, regmap_irq_get_domain(irq_data));
+	if (err)
+		return dev_err_probe(dev, err, "Failed to add devices\n");
+
+	err = devm_register_power_off_handler(dev, pm886_power_off_handler, chip);
+	if (err)
+		return dev_err_probe(dev, err, "Failed to register power off handler\n");
+
+	if (device_property_read_bool(dev, "wakeup-source")) {
+		err = devm_device_init_wakeup(dev);
+		if (err)
+			return dev_err_probe(dev, err, "Failed to init wakeup\n");
+	}
+
+	return 0;
+}
+
+static const struct of_device_id pm886_of_match[] = {
+	{ .compatible = "marvell,88pm886-a1", .data = (void *)PM886_A1_CHIP_ID },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, pm886_of_match);
+
+static struct i2c_driver pm886_i2c_driver = {
+	.driver = {
+		.name = "88pm886",
+		.of_match_table = pm886_of_match,
+	},
+	.probe = pm886_probe,
+};
+module_i2c_driver(pm886_i2c_driver);
+
+MODULE_DESCRIPTION("Marvell 88PM886 PMIC driver");
+MODULE_AUTHOR("Karel Balej <balejk@matfyz.cz>");
+MODULE_LICENSE("GPL");