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, 220 insertions, 0 deletions

diff --git a/drivers/mfd/max77541.c b/drivers/mfd/max77541.c
new file mode 100644
index 000000000..f91b4f537
--- /dev/null
+++ b/drivers/mfd/max77541.c
@@ -0,0 +1,220 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2022 Analog Devices, Inc.
+ * Driver for the MAX77540 and MAX77541
+ */
+
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/max77541.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+
+static const struct regmap_config max77541_regmap_config = {
+	.reg_bits   = 8,
+	.val_bits   = 8,
+};
+
+static const struct regmap_irq max77541_src_irqs[] = {
+	{ .mask = MAX77541_BIT_INT_SRC_TOPSYS },
+	{ .mask = MAX77541_BIT_INT_SRC_BUCK },
+};
+
+static const struct regmap_irq_chip max77541_src_irq_chip = {
+	.name		= "max77541-src",
+	.status_base	= MAX77541_REG_INT_SRC,
+	.mask_base	= MAX77541_REG_INT_SRC_M,
+	.num_regs	= 1,
+	.irqs		= max77541_src_irqs,
+	.num_irqs       = ARRAY_SIZE(max77541_src_irqs),
+};
+
+static const struct regmap_irq max77541_topsys_irqs[] = {
+	{ .mask = MAX77541_BIT_TOPSYS_INT_TJ_120C },
+	{ .mask = MAX77541_BIT_TOPSYS_INT_TJ_140C },
+	{ .mask = MAX77541_BIT_TOPSYS_INT_TSHDN },
+	{ .mask = MAX77541_BIT_TOPSYS_INT_UVLO },
+	{ .mask = MAX77541_BIT_TOPSYS_INT_ALT_SWO },
+	{ .mask = MAX77541_BIT_TOPSYS_INT_EXT_FREQ_DET },
+};
+
+static const struct regmap_irq_chip max77541_topsys_irq_chip = {
+	.name		= "max77541-topsys",
+	.status_base	= MAX77541_REG_TOPSYS_INT,
+	.mask_base	= MAX77541_REG_TOPSYS_INT_M,
+	.num_regs	= 1,
+	.irqs		= max77541_topsys_irqs,
+	.num_irqs	= ARRAY_SIZE(max77541_topsys_irqs),
+};
+
+static const struct regmap_irq max77541_buck_irqs[] = {
+	{ .mask = MAX77541_BIT_BUCK_INT_M1_POK_FLT },
+	{ .mask = MAX77541_BIT_BUCK_INT_M2_POK_FLT },
+	{ .mask = MAX77541_BIT_BUCK_INT_M1_SCFLT },
+	{ .mask = MAX77541_BIT_BUCK_INT_M2_SCFLT },
+};
+
+static const struct regmap_irq_chip max77541_buck_irq_chip = {
+	.name		= "max77541-buck",
+	.status_base	= MAX77541_REG_BUCK_INT,
+	.mask_base	= MAX77541_REG_BUCK_INT_M,
+	.num_regs	= 1,
+	.irqs		= max77541_buck_irqs,
+	.num_irqs	= ARRAY_SIZE(max77541_buck_irqs),
+};
+
+static const struct regmap_irq max77541_adc_irqs[] = {
+	{ .mask = MAX77541_BIT_ADC_INT_CH1_I },
+	{ .mask = MAX77541_BIT_ADC_INT_CH2_I },
+	{ .mask = MAX77541_BIT_ADC_INT_CH3_I },
+	{ .mask = MAX77541_BIT_ADC_INT_CH6_I },
+};
+
+static const struct regmap_irq_chip max77541_adc_irq_chip = {
+	.name		= "max77541-adc",
+	.status_base	= MAX77541_REG_ADC_INT,
+	.mask_base	= MAX77541_REG_ADC_INT_M,
+	.num_regs	= 1,
+	.irqs		= max77541_adc_irqs,
+	.num_irqs	= ARRAY_SIZE(max77541_adc_irqs),
+};
+
+static const struct mfd_cell max77540_devs[] = {
+	MFD_CELL_OF("max77540-regulator", NULL, NULL, 0, 0, NULL),
+};
+
+static const struct mfd_cell max77541_devs[] = {
+	MFD_CELL_OF("max77541-regulator", NULL, NULL, 0, 0, NULL),
+	MFD_CELL_OF("max77541-adc", NULL, NULL, 0, 0, NULL),
+};
+
+static int max77541_pmic_irq_init(struct device *dev)
+{
+	struct max77541 *max77541 = dev_get_drvdata(dev);
+	int irq = max77541->i2c->irq;
+	int ret;
+
+	ret = devm_regmap_add_irq_chip(dev, max77541->regmap, irq,
+				       IRQF_ONESHOT | IRQF_SHARED, 0,
+				       &max77541_src_irq_chip,
+				       &max77541->irq_data);
+	if (ret)
+		return ret;
+
+	ret = devm_regmap_add_irq_chip(dev, max77541->regmap, irq,
+				       IRQF_ONESHOT | IRQF_SHARED, 0,
+				       &max77541_topsys_irq_chip,
+				       &max77541->irq_topsys);
+	if (ret)
+		return ret;
+
+	ret = devm_regmap_add_irq_chip(dev, max77541->regmap, irq,
+				       IRQF_ONESHOT | IRQF_SHARED, 0,
+				       &max77541_buck_irq_chip,
+				       &max77541->irq_buck);
+	if (ret)
+		return ret;
+
+	if (max77541->id == MAX77541) {
+		ret = devm_regmap_add_irq_chip(dev, max77541->regmap, irq,
+					       IRQF_ONESHOT | IRQF_SHARED, 0,
+					       &max77541_adc_irq_chip,
+					       &max77541->irq_adc);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int max77541_pmic_setup(struct device *dev)
+{
+	struct max77541 *max77541 = dev_get_drvdata(dev);
+	const struct mfd_cell *cells;
+	int n_devs;
+	int ret;
+
+	switch (max77541->id) {
+	case MAX77540:
+		cells =  max77540_devs;
+		n_devs = ARRAY_SIZE(max77540_devs);
+		break;
+	case MAX77541:
+		cells =  max77541_devs;
+		n_devs = ARRAY_SIZE(max77541_devs);
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	ret = max77541_pmic_irq_init(dev);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to initialize IRQ\n");
+
+	ret = devm_device_init_wakeup(dev);
+	if (ret)
+		return dev_err_probe(dev, ret, "Unable to init wakeup\n");
+
+	return devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
+				    cells, n_devs, NULL, 0, NULL);
+}
+
+static int max77541_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct max77541 *max77541;
+
+	max77541 = devm_kzalloc(dev, sizeof(*max77541), GFP_KERNEL);
+	if (!max77541)
+		return -ENOMEM;
+
+	i2c_set_clientdata(client, max77541);
+	max77541->i2c = client;
+
+	max77541->id = (uintptr_t)i2c_get_match_data(client);
+	if (!max77541->id)
+		return -EINVAL;
+
+	max77541->regmap = devm_regmap_init_i2c(client,
+						&max77541_regmap_config);
+	if (IS_ERR(max77541->regmap))
+		return dev_err_probe(dev, PTR_ERR(max77541->regmap),
+				     "Failed to allocate register map\n");
+
+	return max77541_pmic_setup(dev);
+}
+
+static const struct of_device_id max77541_of_id[] = {
+	{
+		.compatible = "adi,max77540",
+		.data = (void *)MAX77540,
+	},
+	{
+		.compatible = "adi,max77541",
+		.data = (void *)MAX77541,
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max77541_of_id);
+
+static const struct i2c_device_id max77541_id[] = {
+	{ "max77540", MAX77540 },
+	{ "max77541", MAX77541 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max77541_id);
+
+static struct i2c_driver max77541_driver = {
+	.driver = {
+		.name = "max77541",
+		.of_match_table = max77541_of_id,
+	},
+	.probe = max77541_probe,
+	.id_table = max77541_id,
+};
+module_i2c_driver(max77541_driver);
+
+MODULE_DESCRIPTION("MAX7740/MAX7741 Driver");
+MODULE_AUTHOR("Okan Sahin <okan.sahin@analog.com>");
+MODULE_LICENSE("GPL");