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5dfe4c964a
Many struct file_operations in the kernel can be "const". Marking them const moves these to the .rodata section, which avoids false sharing with potential dirty data. In addition it'll catch accidental writes at compile time to these shared resources. [akpm@osdl.org: sparc64 fix] Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
185 lines
4.0 KiB
C
185 lines
4.0 KiB
C
/* UML hardware watchdog, shamelessly stolen from:
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*
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* SoftDog 0.05: A Software Watchdog Device
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*
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* (c) Copyright 1996 Alan Cox <alan@redhat.com>, All Rights Reserved.
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* http://www.redhat.com
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
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* warranty for any of this software. This material is provided
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* "AS-IS" and at no charge.
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*
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* (c) Copyright 1995 Alan Cox <alan@lxorguk.ukuu.org.uk>
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*
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* Software only watchdog driver. Unlike its big brother the WDT501P
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* driver this won't always recover a failed machine.
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*
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* 03/96: Angelo Haritsis <ah@doc.ic.ac.uk> :
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* Modularised.
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* Added soft_margin; use upon insmod to change the timer delay.
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* NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate
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* minors.
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*
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* 19980911 Alan Cox
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* Made SMP safe for 2.3.x
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*
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* 20011127 Joel Becker (jlbec@evilplan.org>
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* Added soft_noboot; Allows testing the softdog trigger without
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* requiring a recompile.
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* Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT.
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*/
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/miscdevice.h>
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#include <linux/watchdog.h>
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#include <linux/reboot.h>
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#include <linux/smp_lock.h>
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#include <linux/init.h>
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#include <linux/spinlock.h>
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#include <asm/uaccess.h>
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#include "mconsole.h"
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MODULE_LICENSE("GPL");
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static DEFINE_SPINLOCK(lock);
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static int timer_alive;
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static int harddog_in_fd = -1;
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static int harddog_out_fd = -1;
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/*
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* Allow only one person to hold it open
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*/
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extern int start_watchdog(int *in_fd_ret, int *out_fd_ret, char *sock);
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static int harddog_open(struct inode *inode, struct file *file)
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{
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int err = -EBUSY;
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char *sock = NULL;
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spin_lock(&lock);
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if(timer_alive)
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goto err;
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#ifdef CONFIG_HARDDOG_NOWAYOUT
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__module_get(THIS_MODULE);
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#endif
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#ifdef CONFIG_MCONSOLE
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sock = mconsole_notify_socket();
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#endif
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err = start_watchdog(&harddog_in_fd, &harddog_out_fd, sock);
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if(err)
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goto err;
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timer_alive = 1;
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spin_unlock(&lock);
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return nonseekable_open(inode, file);
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err:
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spin_unlock(&lock);
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return err;
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}
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extern void stop_watchdog(int in_fd, int out_fd);
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static int harddog_release(struct inode *inode, struct file *file)
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{
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/*
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* Shut off the timer.
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*/
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spin_lock(&lock);
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stop_watchdog(harddog_in_fd, harddog_out_fd);
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harddog_in_fd = -1;
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harddog_out_fd = -1;
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timer_alive=0;
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spin_unlock(&lock);
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return 0;
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}
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extern int ping_watchdog(int fd);
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static ssize_t harddog_write(struct file *file, const char __user *data, size_t len,
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loff_t *ppos)
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{
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/*
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* Refresh the timer.
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*/
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if(len)
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return ping_watchdog(harddog_out_fd);
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return 0;
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}
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static int harddog_ioctl(struct inode *inode, struct file *file,
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unsigned int cmd, unsigned long arg)
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{
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void __user *argp= (void __user *)arg;
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static struct watchdog_info ident = {
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WDIOC_SETTIMEOUT,
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0,
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"UML Hardware Watchdog"
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};
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switch (cmd) {
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default:
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return -ENOTTY;
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case WDIOC_GETSUPPORT:
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if(copy_to_user(argp, &ident, sizeof(ident)))
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return -EFAULT;
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return 0;
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case WDIOC_GETSTATUS:
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case WDIOC_GETBOOTSTATUS:
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return put_user(0,(int __user *)argp);
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case WDIOC_KEEPALIVE:
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return ping_watchdog(harddog_out_fd);
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}
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}
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static const struct file_operations harddog_fops = {
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.owner = THIS_MODULE,
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.write = harddog_write,
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.ioctl = harddog_ioctl,
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.open = harddog_open,
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.release = harddog_release,
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};
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static struct miscdevice harddog_miscdev = {
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.minor = WATCHDOG_MINOR,
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.name = "watchdog",
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.fops = &harddog_fops,
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};
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static char banner[] __initdata = KERN_INFO "UML Watchdog Timer\n";
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static int __init harddog_init(void)
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{
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int ret;
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ret = misc_register(&harddog_miscdev);
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if (ret)
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return ret;
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printk(banner);
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return 0;
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}
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static void __exit harddog_exit(void)
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{
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misc_deregister(&harddog_miscdev);
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}
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module_init(harddog_init);
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module_exit(harddog_exit);
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