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/mux/gpio.c | 108 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 108 insertions(+) create mode 100644 drivers/mux/gpio.c (limited to 'drivers/mux/gpio.c') diff --git a/drivers/mux/gpio.c b/drivers/mux/gpio.c new file mode 100644 index 000000000..f9c7863e5 --- /dev/null +++ b/drivers/mux/gpio.c @@ -0,0 +1,108 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * GPIO-controlled multiplexer driver + * + * Copyright (C) 2017 Axentia Technologies AB + * + * Author: Peter Rosin + */ + +#include +#include +#include +#include +#include +#include +#include +#include + +struct mux_gpio { + struct gpio_descs *gpios; +}; + +static int mux_gpio_set(struct mux_control *mux, int state) +{ + struct mux_gpio *mux_gpio = mux_chip_priv(mux->chip); + DECLARE_BITMAP(values, BITS_PER_TYPE(state)); + u32 value = state; + + bitmap_from_arr32(values, &value, BITS_PER_TYPE(value)); + + gpiod_multi_set_value_cansleep(mux_gpio->gpios, values); + + return 0; +} + +static const struct mux_control_ops mux_gpio_ops = { + .set = mux_gpio_set, +}; + +static const struct of_device_id mux_gpio_dt_ids[] = { + { .compatible = "gpio-mux", }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, mux_gpio_dt_ids); + +static int mux_gpio_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct mux_chip *mux_chip; + struct mux_gpio *mux_gpio; + int pins; + s32 idle_state; + int ret; + + pins = gpiod_count(dev, "mux"); + if (pins < 0) + return pins; + + mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*mux_gpio)); + if (IS_ERR(mux_chip)) + return PTR_ERR(mux_chip); + + mux_gpio = mux_chip_priv(mux_chip); + mux_chip->ops = &mux_gpio_ops; + + mux_gpio->gpios = devm_gpiod_get_array(dev, "mux", GPIOD_OUT_LOW); + if (IS_ERR(mux_gpio->gpios)) + return dev_err_probe(dev, PTR_ERR(mux_gpio->gpios), + "failed to get gpios\n"); + WARN_ON(pins != mux_gpio->gpios->ndescs); + mux_chip->mux->states = BIT(pins); + + ret = device_property_read_u32(dev, "idle-state", (u32 *)&idle_state); + if (ret >= 0 && idle_state != MUX_IDLE_AS_IS) { + if (idle_state < 0 || idle_state >= mux_chip->mux->states) { + dev_err(dev, "invalid idle-state %u\n", idle_state); + return -EINVAL; + } + + mux_chip->mux->idle_state = idle_state; + } + + ret = devm_regulator_get_enable_optional(dev, "mux"); + if (ret && ret != -ENODEV) + return dev_err_probe(dev, ret, "failed to get/enable mux supply\n"); + + ret = devm_mux_chip_register(dev, mux_chip); + if (ret < 0) + return ret; + + dev_info(dev, "%u-way mux-controller registered\n", + mux_chip->mux->states); + + return 0; +} + +static struct platform_driver mux_gpio_driver = { + .driver = { + .name = "gpio-mux", + .of_match_table = mux_gpio_dt_ids, + }, + .probe = mux_gpio_probe, +}; +module_platform_driver(mux_gpio_driver); + +MODULE_DESCRIPTION("GPIO-controlled multiplexer driver"); +MODULE_AUTHOR("Peter Rosin "); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1