261 lines
6.2 KiB
C
261 lines
6.2 KiB
C
/*
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* Watchdog implementation based on z/VM Watchdog Timer API
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*
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* The user space watchdog daemon can use this driver as
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* /dev/vmwatchdog to have z/VM execute the specified CP
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* command when the timeout expires. The default command is
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* "IPL", which which cause an immediate reboot.
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*/
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#include <linux/init.h>
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#include <linux/fs.h>
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#include <linux/kernel.h>
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#include <linux/miscdevice.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/watchdog.h>
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#include <asm/ebcdic.h>
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#include <asm/io.h>
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#include <asm/uaccess.h>
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#define MAX_CMDLEN 240
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#define MIN_INTERVAL 15
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static char vmwdt_cmd[MAX_CMDLEN] = "IPL";
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static int vmwdt_conceal;
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static int vmwdt_nowayout = WATCHDOG_NOWAYOUT;
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Arnd Bergmann <arndb@de.ibm.com>");
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MODULE_DESCRIPTION("z/VM Watchdog Timer");
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module_param_string(cmd, vmwdt_cmd, MAX_CMDLEN, 0644);
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MODULE_PARM_DESC(cmd, "CP command that is run when the watchdog triggers");
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module_param_named(conceal, vmwdt_conceal, bool, 0644);
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MODULE_PARM_DESC(conceal, "Enable the CONCEAL CP option while the watchdog "
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" is active");
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module_param_named(nowayout, vmwdt_nowayout, bool, 0);
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MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started"
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" (default=CONFIG_WATCHDOG_NOWAYOUT)");
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MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
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static unsigned int vmwdt_interval = 60;
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static unsigned long vmwdt_is_open;
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static int vmwdt_expect_close;
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enum vmwdt_func {
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/* function codes */
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wdt_init = 0,
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wdt_change = 1,
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wdt_cancel = 2,
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/* flags */
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wdt_conceal = 0x80000000,
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};
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static int __diag288(enum vmwdt_func func, unsigned int timeout,
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char *cmd, size_t len)
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{
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register unsigned long __func asm("2") = func;
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register unsigned long __timeout asm("3") = timeout;
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register unsigned long __cmdp asm("4") = virt_to_phys(cmd);
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register unsigned long __cmdl asm("5") = len;
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int err;
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err = -EINVAL;
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asm volatile(
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" diag %1,%3,0x288\n"
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"0: la %0,0\n"
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"1:\n"
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EX_TABLE(0b,1b)
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: "=d" (err) : "d"(__func), "d"(__timeout),
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"d"(__cmdp), "d"(__cmdl), "0" (-EINVAL) : "1", "cc");
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return err;
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}
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static int vmwdt_keepalive(void)
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{
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/* we allocate new memory every time to avoid having
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* to track the state. static allocation is not an
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* option since that might not be contiguous in real
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* storage in case of a modular build */
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static char *ebc_cmd;
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size_t len;
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int ret;
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unsigned int func;
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ebc_cmd = kmalloc(MAX_CMDLEN, GFP_KERNEL);
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if (!ebc_cmd)
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return -ENOMEM;
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len = strlcpy(ebc_cmd, vmwdt_cmd, MAX_CMDLEN);
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ASCEBC(ebc_cmd, MAX_CMDLEN);
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EBC_TOUPPER(ebc_cmd, MAX_CMDLEN);
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func = vmwdt_conceal ? (wdt_init | wdt_conceal) : wdt_init;
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ret = __diag288(func, vmwdt_interval, ebc_cmd, len);
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kfree(ebc_cmd);
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if (ret) {
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printk(KERN_WARNING "%s: problem setting interval %d, "
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"cmd %s\n", __FUNCTION__, vmwdt_interval,
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vmwdt_cmd);
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}
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return ret;
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}
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static int vmwdt_disable(void)
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{
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int ret = __diag288(wdt_cancel, 0, "", 0);
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if (ret) {
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printk(KERN_WARNING "%s: problem disabling watchdog\n",
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__FUNCTION__);
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}
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return ret;
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}
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static int __init vmwdt_probe(void)
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{
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/* there is no real way to see if the watchdog is supported,
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* so we try initializing it with a NOP command ("BEGIN")
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* that won't cause any harm even if the following disable
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* fails for some reason */
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static char __initdata ebc_begin[] = {
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194, 197, 199, 201, 213
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};
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if (__diag288(wdt_init, 15, ebc_begin, sizeof(ebc_begin)) != 0) {
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printk(KERN_INFO "z/VM watchdog not available\n");
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return -EINVAL;
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}
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return vmwdt_disable();
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}
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static int vmwdt_open(struct inode *i, struct file *f)
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{
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int ret;
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if (test_and_set_bit(0, &vmwdt_is_open))
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return -EBUSY;
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ret = vmwdt_keepalive();
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if (ret)
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clear_bit(0, &vmwdt_is_open);
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return ret ? ret : nonseekable_open(i, f);
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}
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static int vmwdt_close(struct inode *i, struct file *f)
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{
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if (vmwdt_expect_close == 42)
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vmwdt_disable();
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vmwdt_expect_close = 0;
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clear_bit(0, &vmwdt_is_open);
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return 0;
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}
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static struct watchdog_info vmwdt_info = {
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.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
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.firmware_version = 0,
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.identity = "z/VM Watchdog Timer",
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};
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static int vmwdt_ioctl(struct inode *i, struct file *f,
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unsigned int cmd, unsigned long arg)
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{
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switch (cmd) {
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case WDIOC_GETSUPPORT:
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if (copy_to_user((void __user *)arg, &vmwdt_info,
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sizeof(vmwdt_info)))
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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 *)arg);
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case WDIOC_GETTEMP:
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return -EINVAL;
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case WDIOC_SETOPTIONS:
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{
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int options, ret;
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if (get_user(options, (int __user *)arg))
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return -EFAULT;
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ret = -EINVAL;
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if (options & WDIOS_DISABLECARD) {
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ret = vmwdt_disable();
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if (ret)
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return ret;
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}
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if (options & WDIOS_ENABLECARD) {
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ret = vmwdt_keepalive();
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}
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return ret;
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}
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case WDIOC_GETTIMEOUT:
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return put_user(vmwdt_interval, (int __user *)arg);
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case WDIOC_SETTIMEOUT:
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{
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int interval;
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if (get_user(interval, (int __user *)arg))
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return -EFAULT;
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if (interval < MIN_INTERVAL)
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return -EINVAL;
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vmwdt_interval = interval;
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}
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return vmwdt_keepalive();
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case WDIOC_KEEPALIVE:
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return vmwdt_keepalive();
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}
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return -EINVAL;
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}
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static ssize_t vmwdt_write(struct file *f, const char __user *buf,
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size_t count, loff_t *ppos)
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{
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if(count) {
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if (!vmwdt_nowayout) {
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size_t i;
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/* note: just in case someone wrote the magic character
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* five months ago... */
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vmwdt_expect_close = 0;
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for (i = 0; i != count; i++) {
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char c;
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if (get_user(c, buf+i))
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return -EFAULT;
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if (c == 'V')
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vmwdt_expect_close = 42;
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}
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}
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/* someone wrote to us, we should restart timer */
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vmwdt_keepalive();
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}
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return count;
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}
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static struct file_operations vmwdt_fops = {
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.open = &vmwdt_open,
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.release = &vmwdt_close,
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.ioctl = &vmwdt_ioctl,
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.write = &vmwdt_write,
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.owner = THIS_MODULE,
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};
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static struct miscdevice vmwdt_dev = {
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.minor = WATCHDOG_MINOR,
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.name = "watchdog",
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.fops = &vmwdt_fops,
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};
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static int __init vmwdt_init(void)
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{
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int ret;
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ret = vmwdt_probe();
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if (ret)
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return ret;
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return misc_register(&vmwdt_dev);
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}
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module_init(vmwdt_init);
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static void __exit vmwdt_exit(void)
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{
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WARN_ON(misc_deregister(&vmwdt_dev) != 0);
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}
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module_exit(vmwdt_exit);
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