From 4617721c502b2ddaa4e324e86da4997edf738fa5 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Wed, 2 Sep 2026 09:55:01 -0400 Subject: ftrace: Synchronize the initialization of ftrace_ops 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 --- drivers/mfd/rt4831.c | 119 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 119 insertions(+) create mode 100644 drivers/mfd/rt4831.c (limited to 'drivers/mfd/rt4831.c') diff --git a/drivers/mfd/rt4831.c b/drivers/mfd/rt4831.c new file mode 100644 index 000000000..1ab8870e4 --- /dev/null +++ b/drivers/mfd/rt4831.c @@ -0,0 +1,119 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright (c) 2021 Richtek Technology Corp. + * + * Author: ChiYuan Huang + */ + +#include +#include +#include +#include +#include +#include + +#define RT4831_REG_REVISION 0x01 +#define RT4831_REG_ENABLE 0x08 +#define RT4831_REG_I2CPROT 0x15 + +#define RICHTEK_VENDOR_ID 0x03 +#define RT4831_VID_MASK GENMASK(1, 0) +#define RT4831_RESET_MASK BIT(7) +#define RT4831_I2CSAFETMR_MASK BIT(0) + +static const struct mfd_cell rt4831_subdevs[] = { + MFD_CELL_OF("rt4831-backlight", NULL, NULL, 0, 0, "richtek,rt4831-backlight"), + MFD_CELL_NAME("rt4831-regulator") +}; + +static bool rt4831_is_accessible_reg(struct device *dev, unsigned int reg) +{ + if (reg >= RT4831_REG_REVISION && reg <= RT4831_REG_I2CPROT) + return true; + return false; +} + +static const struct regmap_config rt4831_regmap_config = { + .reg_bits = 8, + .val_bits = 8, + .max_register = RT4831_REG_I2CPROT, + + .readable_reg = rt4831_is_accessible_reg, + .writeable_reg = rt4831_is_accessible_reg, +}; + +static int rt4831_probe(struct i2c_client *client) +{ + struct gpio_desc *enable_gpio; + struct regmap *regmap; + unsigned int chip_id; + int ret; + + enable_gpio = devm_gpiod_get_optional(&client->dev, "enable", GPIOD_OUT_HIGH); + if (IS_ERR(enable_gpio)) { + dev_err(&client->dev, "Failed to get 'enable' GPIO\n"); + return PTR_ERR(enable_gpio); + } + + regmap = devm_regmap_init_i2c(client, &rt4831_regmap_config); + if (IS_ERR(regmap)) { + dev_err(&client->dev, "Failed to initialize regmap\n"); + return PTR_ERR(regmap); + } + + ret = regmap_read(regmap, RT4831_REG_REVISION, &chip_id); + if (ret) { + dev_err(&client->dev, "Failed to get H/W revision\n"); + return ret; + } + + if ((chip_id & RT4831_VID_MASK) != RICHTEK_VENDOR_ID) { + dev_err(&client->dev, "Chip vendor ID 0x%02x not matched\n", chip_id); + return -ENODEV; + } + + /* + * Used to prevent the abnormal shutdown. + * If SCL/SDA both keep low for one second to reset HW. + */ + ret = regmap_update_bits(regmap, RT4831_REG_I2CPROT, RT4831_I2CSAFETMR_MASK, + RT4831_I2CSAFETMR_MASK); + if (ret) { + dev_err(&client->dev, "Failed to enable I2C safety timer\n"); + return ret; + } + + return devm_mfd_add_devices(&client->dev, PLATFORM_DEVID_AUTO, rt4831_subdevs, + ARRAY_SIZE(rt4831_subdevs), NULL, 0, NULL); +} + +static void rt4831_remove(struct i2c_client *client) +{ + struct regmap *regmap = dev_get_regmap(&client->dev, NULL); + int ret; + + /* Disable WLED and DSV outputs */ + ret = regmap_update_bits(regmap, RT4831_REG_ENABLE, RT4831_RESET_MASK, RT4831_RESET_MASK); + if (ret) + dev_warn(&client->dev, "Failed to disable outputs (%pe)\n", ERR_PTR(ret)); +} + +static const struct of_device_id __maybe_unused rt4831_of_match[] = { + { .compatible = "richtek,rt4831", }, + {} +}; +MODULE_DEVICE_TABLE(of, rt4831_of_match); + +static struct i2c_driver rt4831_driver = { + .driver = { + .name = "rt4831", + .of_match_table = rt4831_of_match, + }, + .probe = rt4831_probe, + .remove = rt4831_remove, +}; +module_i2c_driver(rt4831_driver); + +MODULE_AUTHOR("ChiYuan Huang "); +MODULE_DESCRIPTION("Richtek RT4831 core driver"); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1