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/iio/buffer/industrialio-triggered-buffer.c | 139 +++++++++++++++++++++ 1 file changed, 139 insertions(+) create mode 100644 drivers/iio/buffer/industrialio-triggered-buffer.c (limited to 'drivers/iio/buffer/industrialio-triggered-buffer.c') diff --git a/drivers/iio/buffer/industrialio-triggered-buffer.c b/drivers/iio/buffer/industrialio-triggered-buffer.c new file mode 100644 index 000000000..9bf75dee7 --- /dev/null +++ b/drivers/iio/buffer/industrialio-triggered-buffer.c @@ -0,0 +1,139 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (c) 2012 Analog Devices, Inc. + * Author: Lars-Peter Clausen + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/** + * iio_triggered_buffer_setup_ext() - Setup triggered buffer and pollfunc + * @indio_dev: IIO device structure + * @h: Function which will be used as pollfunc top half + * @thread: Function which will be used as pollfunc bottom half + * @direction: Direction of the data stream (in/out). + * @setup_ops: Buffer setup functions to use for this device. + * If NULL the default setup functions for triggered + * buffers will be used. + * @buffer_attrs: Extra sysfs buffer attributes for this IIO buffer + * + * This function combines some common tasks which will normally be performed + * when setting up a triggered buffer. It will allocate the buffer and the + * pollfunc. + * + * Before calling this function the indio_dev structure should already be + * completely initialized, but not yet registered. In practice this means that + * this function should be called right before iio_device_register(). + * + * To free the resources allocated by this function call + * iio_triggered_buffer_cleanup(). + */ +int iio_triggered_buffer_setup_ext(struct iio_dev *indio_dev, + irqreturn_t (*h)(int irq, void *p), + irqreturn_t (*thread)(int irq, void *p), + enum iio_buffer_direction direction, + const struct iio_buffer_setup_ops *setup_ops, + const struct iio_dev_attr **buffer_attrs) +{ + struct iio_buffer *buffer; + int ret; + + /* + * iio_triggered_buffer_cleanup() assumes that the buffer allocated here + * is assigned to indio_dev->buffer but this is only the case if this + * function is the first caller to iio_device_attach_buffer(). If + * indio_dev->buffer is already set then we can't proceed otherwise the + * cleanup function will try to free a buffer that was not allocated here. + */ + if (indio_dev->buffer) + return -EADDRINUSE; + + buffer = iio_kfifo_allocate(); + if (!buffer) { + ret = -ENOMEM; + goto error_ret; + } + + indio_dev->pollfunc = iio_alloc_pollfunc(h, + thread, + IRQF_ONESHOT, + indio_dev, + "%s_consumer%d", + indio_dev->name, + iio_device_id(indio_dev)); + if (indio_dev->pollfunc == NULL) { + ret = -ENOMEM; + goto error_kfifo_free; + } + + /* Ring buffer functions - here trigger setup related */ + indio_dev->setup_ops = setup_ops; + + /* Flag that polled ring buffering is possible */ + indio_dev->modes |= INDIO_BUFFER_TRIGGERED; + + buffer->direction = direction; + buffer->attrs = buffer_attrs; + + ret = iio_device_attach_buffer(indio_dev, buffer); + if (ret < 0) + goto error_dealloc_pollfunc; + + return 0; + +error_dealloc_pollfunc: + iio_dealloc_pollfunc(indio_dev->pollfunc); +error_kfifo_free: + iio_kfifo_free(buffer); +error_ret: + return ret; +} +EXPORT_SYMBOL(iio_triggered_buffer_setup_ext); + +/** + * iio_triggered_buffer_cleanup() - Free resources allocated by iio_triggered_buffer_setup_ext() + * @indio_dev: IIO device structure + */ +void iio_triggered_buffer_cleanup(struct iio_dev *indio_dev) +{ + iio_dealloc_pollfunc(indio_dev->pollfunc); + iio_kfifo_free(indio_dev->buffer); +} +EXPORT_SYMBOL(iio_triggered_buffer_cleanup); + +static void devm_iio_triggered_buffer_clean(void *indio_dev) +{ + iio_triggered_buffer_cleanup(indio_dev); +} + +int devm_iio_triggered_buffer_setup_ext(struct device *dev, + struct iio_dev *indio_dev, + irqreturn_t (*h)(int irq, void *p), + irqreturn_t (*thread)(int irq, void *p), + enum iio_buffer_direction direction, + const struct iio_buffer_setup_ops *ops, + const struct iio_dev_attr **buffer_attrs) +{ + int ret; + + ret = iio_triggered_buffer_setup_ext(indio_dev, h, thread, direction, + ops, buffer_attrs); + if (ret) + return ret; + + return devm_add_action_or_reset(dev, devm_iio_triggered_buffer_clean, + indio_dev); +} +EXPORT_SYMBOL_GPL(devm_iio_triggered_buffer_setup_ext); + +MODULE_AUTHOR("Lars-Peter Clausen "); +MODULE_DESCRIPTION("IIO helper functions for setting up triggered buffers"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1