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, 217 insertions, 0 deletions

diff --git a/drivers/mfd/max77843.c b/drivers/mfd/max77843.c
new file mode 100644
index 000000000..2a48577b1
--- /dev/null
+++ b/drivers/mfd/max77843.c
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+// MFD core driver for the Maxim MAX77843
+//
+// Copyright (C) 2015 Samsung Electronics
+// Author: Jaewon Kim <jaewon02.kim@samsung.com>
+// Author: Beomho Seo <beomho.seo@samsung.com>
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/max77693-common.h>
+#include <linux/mfd/max77843-private.h>
+#include <linux/platform_device.h>
+
+static const struct mfd_cell max77843_devs[] = {
+	{
+		.name = "max77843-muic",
+		.of_compatible = "maxim,max77843-muic",
+	}, {
+		.name = "max77843-regulator",
+		.of_compatible = "maxim,max77843-regulator",
+	}, {
+		.name = "max77843-charger",
+		.of_compatible = "maxim,max77843-charger"
+	}, {
+		.name = "max77843-fuelgauge",
+		.of_compatible = "maxim,max77843-fuelgauge",
+	}, {
+		.name = "max77843-haptic",
+		.of_compatible = "maxim,max77843-haptic",
+	},
+};
+
+static const struct regmap_config max77843_charger_regmap_config = {
+	.reg_bits	= 8,
+	.val_bits	= 8,
+	.max_register	= MAX77843_CHG_REG_END,
+};
+
+static const struct regmap_config max77843_regmap_config = {
+	.reg_bits	= 8,
+	.val_bits	= 8,
+	.max_register	= MAX77843_SYS_REG_END,
+};
+
+static const struct regmap_irq max77843_irqs[] = {
+	/* TOPSYS interrupts */
+	{ .reg_offset = 0, .mask = MAX77843_SYS_IRQ_SYSUVLO_INT, },
+	{ .reg_offset = 0, .mask = MAX77843_SYS_IRQ_SYSOVLO_INT, },
+	{ .reg_offset = 0, .mask = MAX77843_SYS_IRQ_TSHDN_INT, },
+	{ .reg_offset = 0, .mask = MAX77843_SYS_IRQ_TM_INT, },
+};
+
+static const struct regmap_irq_chip max77843_irq_chip = {
+	.name		= "max77843",
+	.status_base	= MAX77843_SYS_REG_SYSINTSRC,
+	.mask_base	= MAX77843_SYS_REG_SYSINTMASK,
+	.num_regs	= 1,
+	.irqs		= max77843_irqs,
+	.num_irqs	= ARRAY_SIZE(max77843_irqs),
+};
+
+/* Charger and Charger regulator use same regmap. */
+static int max77843_chg_init(struct max77693_dev *max77843)
+{
+	int ret;
+
+	max77843->i2c_chg = i2c_new_dummy_device(max77843->i2c->adapter, I2C_ADDR_CHG);
+	if (IS_ERR(max77843->i2c_chg)) {
+		dev_err(&max77843->i2c->dev,
+				"Cannot allocate I2C device for Charger\n");
+		return PTR_ERR(max77843->i2c_chg);
+	}
+	i2c_set_clientdata(max77843->i2c_chg, max77843);
+
+	max77843->regmap_chg = devm_regmap_init_i2c(max77843->i2c_chg,
+			&max77843_charger_regmap_config);
+	if (IS_ERR(max77843->regmap_chg)) {
+		ret = PTR_ERR(max77843->regmap_chg);
+		goto err_chg_i2c;
+	}
+
+	return 0;
+
+err_chg_i2c:
+	i2c_unregister_device(max77843->i2c_chg);
+
+	return ret;
+}
+
+static int max77843_probe(struct i2c_client *i2c)
+{
+	const struct i2c_device_id *id = i2c_client_get_device_id(i2c);
+	struct max77693_dev *max77843;
+	unsigned int reg_data;
+	int ret;
+
+	max77843 = devm_kzalloc(&i2c->dev, sizeof(*max77843), GFP_KERNEL);
+	if (!max77843)
+		return -ENOMEM;
+
+	i2c_set_clientdata(i2c, max77843);
+	max77843->dev = &i2c->dev;
+	max77843->i2c = i2c;
+	max77843->irq = i2c->irq;
+	max77843->type = id->driver_data;
+
+	max77843->regmap = devm_regmap_init_i2c(i2c,
+			&max77843_regmap_config);
+	if (IS_ERR(max77843->regmap)) {
+		dev_err(&i2c->dev, "Failed to allocate topsys register map\n");
+		return PTR_ERR(max77843->regmap);
+	}
+
+	ret = regmap_add_irq_chip(max77843->regmap, max77843->irq,
+			IRQF_TRIGGER_LOW | IRQF_ONESHOT | IRQF_SHARED,
+			0, &max77843_irq_chip, &max77843->irq_data_topsys);
+	if (ret) {
+		dev_err(&i2c->dev, "Failed to add TOPSYS IRQ chip\n");
+		return ret;
+	}
+
+	ret = regmap_read(max77843->regmap,
+			MAX77843_SYS_REG_PMICID, &reg_data);
+	if (ret < 0) {
+		dev_err(&i2c->dev, "Failed to read PMIC ID\n");
+		goto err_pmic_id;
+	}
+	dev_info(&i2c->dev, "device ID: 0x%x\n", reg_data);
+
+	ret = max77843_chg_init(max77843);
+	if (ret) {
+		dev_err(&i2c->dev, "Failed to init Charger\n");
+		goto err_pmic_id;
+	}
+
+	ret = regmap_update_bits(max77843->regmap,
+				 MAX77843_SYS_REG_INTSRCMASK,
+				 MAX77843_INTSRC_MASK_MASK,
+				 (unsigned int)~MAX77843_INTSRC_MASK_MASK);
+	if (ret < 0) {
+		dev_err(&i2c->dev, "Failed to unmask interrupt source\n");
+		goto err_pmic_id;
+	}
+
+	ret = mfd_add_devices(max77843->dev, -1, max77843_devs,
+			      ARRAY_SIZE(max77843_devs), NULL, 0, NULL);
+	if (ret < 0) {
+		dev_err(&i2c->dev, "Failed to add mfd device\n");
+		goto err_pmic_id;
+	}
+
+	device_init_wakeup(max77843->dev, true);
+
+	return 0;
+
+err_pmic_id:
+	regmap_del_irq_chip(max77843->irq, max77843->irq_data_topsys);
+
+	return ret;
+}
+
+static const struct of_device_id max77843_dt_match[] = {
+	{ .compatible = "maxim,max77843", },
+	{ },
+};
+
+static const struct i2c_device_id max77843_id[] = {
+	{ "max77843", TYPE_MAX77843, },
+	{ },
+};
+
+static int __maybe_unused max77843_suspend(struct device *dev)
+{
+	struct i2c_client *i2c = to_i2c_client(dev);
+	struct max77693_dev *max77843 = i2c_get_clientdata(i2c);
+
+	disable_irq(max77843->irq);
+	if (device_may_wakeup(dev))
+		enable_irq_wake(max77843->irq);
+
+	return 0;
+}
+
+static int __maybe_unused max77843_resume(struct device *dev)
+{
+	struct i2c_client *i2c = to_i2c_client(dev);
+	struct max77693_dev *max77843 = i2c_get_clientdata(i2c);
+
+	if (device_may_wakeup(dev))
+		disable_irq_wake(max77843->irq);
+	enable_irq(max77843->irq);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(max77843_pm, max77843_suspend, max77843_resume);
+
+static struct i2c_driver max77843_i2c_driver = {
+	.driver	= {
+		.name = "max77843",
+		.pm = &max77843_pm,
+		.of_match_table = max77843_dt_match,
+		.suppress_bind_attrs = true,
+	},
+	.probe = max77843_probe,
+	.id_table = max77843_id,
+};
+
+static int __init max77843_i2c_init(void)
+{
+	return i2c_add_driver(&max77843_i2c_driver);
+}
+subsys_initcall(max77843_i2c_init);