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/parisc/eisa_eeprom.c | 100 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 100 insertions(+) create mode 100644 drivers/parisc/eisa_eeprom.c (limited to 'drivers/parisc/eisa_eeprom.c') diff --git a/drivers/parisc/eisa_eeprom.c b/drivers/parisc/eisa_eeprom.c new file mode 100644 index 000000000..2058b4c5b --- /dev/null +++ b/drivers/parisc/eisa_eeprom.c @@ -0,0 +1,100 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * EISA "eeprom" support routines + * + * Copyright (C) 2001 Thomas Bogendoerfer + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static loff_t eisa_eeprom_llseek(struct file *file, loff_t offset, int origin) +{ + return fixed_size_llseek(file, offset, origin, HPEE_MAX_LENGTH); +} + +static ssize_t eisa_eeprom_read(struct file * file, + char __user *buf, size_t count, loff_t *ppos ) +{ + unsigned char *tmp; + ssize_t ret; + int i; + + if (*ppos < 0 || *ppos >= HPEE_MAX_LENGTH) + return 0; + + count = *ppos + count < HPEE_MAX_LENGTH ? count : HPEE_MAX_LENGTH - *ppos; + tmp = kmalloc(count, GFP_KERNEL); + if (tmp) { + for (i = 0; i < count; i++) + tmp[i] = readb(eisa_eeprom_addr+(*ppos)++); + + if (copy_to_user (buf, tmp, count)) + ret = -EFAULT; + else + ret = count; + kfree (tmp); + } else + ret = -ENOMEM; + + return ret; +} + +static int eisa_eeprom_open(struct inode *inode, struct file *file) +{ + if (file->f_mode & FMODE_WRITE) + return -EINVAL; + + return 0; +} + +static int eisa_eeprom_release(struct inode *inode, struct file *file) +{ + return 0; +} + +/* + * The various file operations we support. + */ +static const struct file_operations eisa_eeprom_fops = { + .owner = THIS_MODULE, + .llseek = eisa_eeprom_llseek, + .read = eisa_eeprom_read, + .open = eisa_eeprom_open, + .release = eisa_eeprom_release, +}; + +static struct miscdevice eisa_eeprom_dev = { + EISA_EEPROM_MINOR, + "eisa_eeprom", + &eisa_eeprom_fops +}; + +static int __init eisa_eeprom_init(void) +{ + int retval; + + if (!eisa_eeprom_addr) + return -ENODEV; + + retval = misc_register(&eisa_eeprom_dev); + if (retval < 0) { + printk(KERN_ERR "EISA EEPROM: cannot register misc device.\n"); + return retval; + } + + printk(KERN_INFO "EISA EEPROM at 0x%px\n", eisa_eeprom_addr); + return 0; +} + +MODULE_DESCRIPTION("EISA eeprom driver"); +MODULE_LICENSE("GPL"); + +module_init(eisa_eeprom_init); -- cgit v1.3.1