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/ec_sys.c | 144 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 144 insertions(+) create mode 100644 drivers/acpi/ec_sys.c (limited to 'drivers/acpi/ec_sys.c') diff --git a/drivers/acpi/ec_sys.c b/drivers/acpi/ec_sys.c new file mode 100644 index 000000000..c074a0fae --- /dev/null +++ b/drivers/acpi/ec_sys.c @@ -0,0 +1,144 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * ec_sys.c + * + * Copyright (C) 2010 SUSE Products GmbH/Novell + * Author: + * Thomas Renninger + */ + +#include +#include +#include +#include +#include +#include "internal.h" + +MODULE_AUTHOR("Thomas Renninger "); +MODULE_DESCRIPTION("ACPI EC sysfs access driver"); +MODULE_LICENSE("GPL"); + +static bool write_support; +module_param_hw(write_support, bool, other, 0644); +MODULE_PARM_DESC(write_support, "Dangerous, reboot and removal of battery may " + "be needed."); + +#define EC_SPACE_SIZE 256 + +static struct dentry *acpi_ec_debugfs_dir; + +static ssize_t acpi_ec_read_io(struct file *f, char __user *buf, + size_t count, loff_t *off) +{ + /* Use this if support reading/writing multiple ECs exists in ec.c: + * struct acpi_ec *ec = ((struct seq_file *)f->private_data)->private; + */ + unsigned int size = EC_SPACE_SIZE; + loff_t init_off = *off; + int err = 0; + + if (*off >= size) + return 0; + if (*off + count >= size) { + size -= *off; + count = size; + } else + size = count; + + while (size) { + u8 byte_read; + err = ec_read(*off, &byte_read); + if (err) + return err; + if (put_user(byte_read, buf + *off - init_off)) { + if (*off - init_off) + return *off - init_off; /* partial read */ + return -EFAULT; + } + *off += 1; + size--; + } + return count; +} + +static ssize_t acpi_ec_write_io(struct file *f, const char __user *buf, + size_t count, loff_t *off) +{ + /* Use this if support reading/writing multiple ECs exists in ec.c: + * struct acpi_ec *ec = ((struct seq_file *)f->private_data)->private; + */ + + unsigned int size = count; + loff_t init_off = *off; + int err = 0; + + if (!write_support) + return -EINVAL; + + if (*off >= EC_SPACE_SIZE) + return 0; + if (*off + count >= EC_SPACE_SIZE) { + size = EC_SPACE_SIZE - *off; + count = size; + } + + while (size) { + u8 byte_write; + if (get_user(byte_write, buf + *off - init_off)) { + if (*off - init_off) + return *off - init_off; /* partial write */ + return -EFAULT; + } + err = ec_write(*off, byte_write); + if (err) + return err; + + *off += 1; + size--; + } + return count; +} + +static const struct file_operations acpi_ec_io_ops = { + .owner = THIS_MODULE, + .open = simple_open, + .read = acpi_ec_read_io, + .write = acpi_ec_write_io, + .llseek = default_llseek, +}; + +static void acpi_ec_add_debugfs(struct acpi_ec *ec, unsigned int ec_device_count) +{ + struct dentry *dev_dir; + char name[64]; + umode_t mode = 0400; + + if (ec_device_count == 0) + acpi_ec_debugfs_dir = debugfs_create_dir("ec", NULL); + + sprintf(name, "ec%u", ec_device_count); + dev_dir = debugfs_create_dir(name, acpi_ec_debugfs_dir); + + debugfs_create_x32("gpe", 0444, dev_dir, &first_ec->gpe); + debugfs_create_bool("use_global_lock", 0444, dev_dir, + &first_ec->global_lock); + + if (write_support) + mode = 0600; + debugfs_create_file("io", mode, dev_dir, ec, &acpi_ec_io_ops); +} + +static int __init acpi_ec_sys_init(void) +{ + if (first_ec) + acpi_ec_add_debugfs(first_ec, 0); + return 0; +} + +static void __exit acpi_ec_sys_exit(void) +{ + debugfs_remove_recursive(acpi_ec_debugfs_dir); +} + +module_init(acpi_ec_sys_init); +module_exit(acpi_ec_sys_exit); -- cgit v1.3.1