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/acpi/tiny-power-button.c | 87 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 87 insertions(+) create mode 100644 drivers/acpi/tiny-power-button.c (limited to 'drivers/acpi/tiny-power-button.c') diff --git a/drivers/acpi/tiny-power-button.c b/drivers/acpi/tiny-power-button.c new file mode 100644 index 000000000..92516ef84 --- /dev/null +++ b/drivers/acpi/tiny-power-button.c @@ -0,0 +1,87 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +#include +#include +#include +#include +#include + +MODULE_AUTHOR("Josh Triplett"); +MODULE_DESCRIPTION("ACPI Tiny Power Button Driver"); +MODULE_LICENSE("GPL"); + +static int power_signal __read_mostly = CONFIG_ACPI_TINY_POWER_BUTTON_SIGNAL; +module_param(power_signal, int, 0644); +MODULE_PARM_DESC(power_signal, "Power button sends this signal to init"); + +static const struct acpi_device_id tiny_power_button_device_ids[] = { + { ACPI_BUTTON_HID_POWER, 0 }, + { ACPI_BUTTON_HID_POWERF, 0 }, + { "", 0 }, +}; +MODULE_DEVICE_TABLE(acpi, tiny_power_button_device_ids); + +static void acpi_tiny_power_button_notify(acpi_handle handle, u32 event, void *data) +{ + kill_cad_pid(power_signal, 1); +} + +static void acpi_tiny_power_button_notify_run(void *not_used) +{ + acpi_tiny_power_button_notify(NULL, ACPI_FIXED_HARDWARE_EVENT, NULL); +} + +static u32 acpi_tiny_power_button_event(void *not_used) +{ + acpi_os_execute(OSL_NOTIFY_HANDLER, acpi_tiny_power_button_notify_run, NULL); + return ACPI_INTERRUPT_HANDLED; +} + +static int acpi_tiny_power_button_probe(struct platform_device *pdev) +{ + struct acpi_device *device; + acpi_status status; + + device = ACPI_COMPANION(&pdev->dev); + if (!device) + return -ENODEV; + + if (device->device_type == ACPI_BUS_TYPE_POWER_BUTTON) { + status = acpi_install_fixed_event_handler(ACPI_EVENT_POWER_BUTTON, + acpi_tiny_power_button_event, + NULL); + } else { + status = acpi_install_notify_handler(device->handle, + ACPI_DEVICE_NOTIFY, + acpi_tiny_power_button_notify, + NULL); + } + if (ACPI_FAILURE(status)) + return -ENODEV; + + return 0; +} + +static void acpi_tiny_power_button_remove(struct platform_device *pdev) +{ + struct acpi_device *device = ACPI_COMPANION(&pdev->dev); + + if (device->device_type == ACPI_BUS_TYPE_POWER_BUTTON) { + acpi_remove_fixed_event_handler(ACPI_EVENT_POWER_BUTTON, + acpi_tiny_power_button_event); + } else { + acpi_remove_notify_handler(device->handle, ACPI_DEVICE_NOTIFY, + acpi_tiny_power_button_notify); + } + acpi_os_wait_events_complete(); +} + +static struct platform_driver acpi_tiny_power_button_driver = { + .probe = acpi_tiny_power_button_probe, + .remove = acpi_tiny_power_button_remove, + .driver = { + .name = "acpi-tiny-power-button", + .acpi_match_table = tiny_power_button_device_ids, + }, +}; + +module_platform_driver(acpi_tiny_power_button_driver); -- cgit v1.3.1