1 files changed, 203 insertions, 180 deletions

diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
index 7ba3fc6..3cab6f6 100644
--- a/drivers/watchdog/watchdog_dev.c
+++ b/drivers/watchdog/watchdog_dev.c
@@ -32,27 +32,51 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
-#include <linux/module.h>	/* For module stuff/... */
-#include <linux/types.h>	/* For standard types (like size_t) */
+#include <linux/cdev.h>		/* For character device */
 #include <linux/errno.h>	/* For the -ENODEV/... values */
-#include <linux/kernel.h>	/* For printk/panic/... */
 #include <linux/fs.h>		/* For file operations */
-#include <linux/watchdog.h>	/* For watchdog specific items */
-#include <linux/miscdevice.h>	/* For handling misc devices */
 #include <linux/init.h>		/* For __init/__exit/... */
+#include <linux/kernel.h>	/* For printk/panic/... */
+#include <linux/kref.h>		/* For data references */
+#include <linux/miscdevice.h>	/* For handling misc devices */
+#include <linux/module.h>	/* For module stuff/... */
+#include <linux/mutex.h>	/* For mutexes */
+#include <linux/slab.h>		/* For memory functions */
+#include <linux/types.h>	/* For standard types (like size_t) */
+#include <linux/watchdog.h>	/* For watchdog specific items */
 #include <linux/uaccess.h>	/* For copy_to_user/put_user/... */
 
 #include "watchdog_core.h"
 
+/*
+ * struct watchdog_core_data - watchdog core internal data
+ * @kref:	Reference count.
+ * @cdev:	The watchdog's Character device.
+ * @wdd:	Pointer to watchdog device.
+ * @lock:	Lock for watchdog core.
+ * @status:	Watchdog core internal status bits.
+ */
+struct watchdog_core_data {
+	struct kref kref;
+	struct cdev cdev;
+	struct watchdog_device *wdd;
+	struct mutex lock;
+	unsigned long status;		/* Internal status bits */
+#define _WDOG_DEV_OPEN		0	/* Opened ? */
+#define _WDOG_ALLOW_RELEASE	1	/* Did we receive the magic char ? */
+};
+
 /* the dev_t structure to store the dynamically allocated watchdog devices */
 static dev_t watchdog_devt;
-/* the watchdog device behind /dev/watchdog */
-static struct watchdog_device *old_wdd;
+/* Reference to watchdog device behind /dev/watchdog */
+static struct watchdog_core_data *old_wd_data;
 
 /*
  *	watchdog_ping: ping the watchdog.
  *	@wdd: the watchdog device to ping
  *
+ *	The caller must hold wd_data->lock.
+ *
  *	If the watchdog has no own ping operation then it needs to be
  *	restarted via the start operation. This wrapper function does
  *	exactly that.
@@ -61,25 +85,16 @@ static struct watchdog_device *old_wdd;
 
 static int watchdog_ping(struct watchdog_device *wdd)
 {
-	int err = 0;
-
-	mutex_lock(&wdd->lock);
-
-	if (test_bit(WDOG_UNREGISTERED, &wdd->status)) {
-		err = -ENODEV;
-		goto out_ping;
-	}
+	int err;
 
 	if (!watchdog_active(wdd))
-		goto out_ping;
+		return 0;
 
 	if (wdd->ops->ping)
 		err = wdd->ops->ping(wdd);	/* ping the watchdog */
 	else
 		err = wdd->ops->start(wdd);	/* restart watchdog */
 
-out_ping:
-	mutex_unlock(&wdd->lock);
 	return err;
 }
 
@@ -87,6 +102,8 @@ out_ping:
  *	watchdog_start: wrapper to start the watchdog.
  *	@wdd: the watchdog device to start
  *
+ *	The caller must hold wd_data->lock.
+ *
  *	Start the watchdog if it is not active and mark it active.
  *	This function returns zero on success or a negative errno code for
  *	failure.
@@ -94,24 +111,15 @@ out_ping:
 
 static int watchdog_start(struct watchdog_device *wdd)
 {
-	int err = 0;
-
-	mutex_lock(&wdd->lock);
-
-	if (test_bit(WDOG_UNREGISTERED, &wdd->status)) {
-		err = -ENODEV;
-		goto out_start;
-	}
+	int err;
 
 	if (watchdog_active(wdd))
-		goto out_start;
+		return 0;
 
 	err = wdd->ops->start(wdd);
 	if (err == 0)
 		set_bit(WDOG_ACTIVE, &wdd->status);
 
-out_start:
-	mutex_unlock(&wdd->lock);
 	return err;
 }
 
@@ -119,6 +127,8 @@ out_start:
  *	watchdog_stop: wrapper to stop the watchdog.
  *	@wdd: the watchdog device to stop
  *
+ *	The caller must hold wd_data->lock.
+ *
  *	Stop the watchdog if it is still active and unmark it active.
  *	This function returns zero on success or a negative errno code for
  *	failure.
@@ -127,93 +137,58 @@ out_start:
 
 static int watchdog_stop(struct watchdog_device *wdd)
 {
-	int err = 0;
-
-	mutex_lock(&wdd->lock);
-
-	if (test_bit(WDOG_UNREGISTERED, &wdd->status)) {
-		err = -ENODEV;
-		goto out_stop;
-	}
+	int err;
 
 	if (!watchdog_active(wdd))
-		goto out_stop;
+		return 0;
 
 	if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) {
 		dev_info(wdd->dev, "nowayout prevents watchdog being stopped!\n");
-		err = -EBUSY;
-		goto out_stop;
+		return -EBUSY;
 	}
 
 	err = wdd->ops->stop(wdd);
 	if (err == 0)
 		clear_bit(WDOG_ACTIVE, &wdd->status);
 
-out_stop:
-	mutex_unlock(&wdd->lock);
 	return err;
 }
 
 /*
  *	watchdog_get_status: wrapper to get the watchdog status
  *	@wdd: the watchdog device to get the status from
- *	@status: the status of the watchdog device
+ *
+ *	The caller must hold wd_data->lock.
  *
  *	Get the watchdog's status flags.
  */
 
-static int watchdog_get_status(struct watchdog_device *wdd,
-							unsigned int *status)
+static unsigned int watchdog_get_status(struct watchdog_device *wdd)
 {
-	int err = 0;
-
-	*status = 0;
 	if (!wdd->ops->status)
-		return -EOPNOTSUPP;
-
-	mutex_lock(&wdd->lock);
-
-	if (test_bit(WDOG_UNREGISTERED, &wdd->status)) {
-		err = -ENODEV;
-		goto out_status;
-	}
-
-	*status = wdd->ops->status(wdd);
+		return 0;
 
-out_status:
-	mutex_unlock(&wdd->lock);
-	return err;
+	return wdd->ops->status(wdd);
 }
 
 /*
  *	watchdog_set_timeout: set the watchdog timer timeout
  *	@wdd: the watchdog device to set the timeout for
  *	@timeout: timeout to set in seconds
+ *
+ *	The caller must hold wd_data->lock.
  */
 
 static int watchdog_set_timeout(struct watchdog_device *wdd,
 							unsigned int timeout)
 {
-	int err;
-
 	if (!wdd->ops->set_timeout || !(wdd->info->options & WDIOF_SETTIMEOUT))
 		return -EOPNOTSUPP;
 
 	if (watchdog_timeout_invalid(wdd, timeout))
 		return -EINVAL;
 
-	mutex_lock(&wdd->lock);
-
-	if (test_bit(WDOG_UNREGISTERED, &wdd->status)) {
-		err = -ENODEV;
-		goto out_timeout;
-	}
-
-	err = wdd->ops->set_timeout(wdd, timeout);
-
-out_timeout:
-	mutex_unlock(&wdd->lock);
-	return err;
+	return wdd->ops->set_timeout(wdd, timeout);
 }
 
 /*
@@ -221,30 +196,22 @@ out_timeout:
  *	@wdd: the watchdog device to get the remaining time from
  *	@timeleft: the time that's left
  *
+ *	The caller must hold wd_data->lock.
+ *
  *	Get the time before a watchdog will reboot (if not pinged).
  */
 
 static int watchdog_get_timeleft(struct watchdog_device *wdd,
 							unsigned int *timeleft)
 {
-	int err = 0;
-
 	*timeleft = 0;
+
 	if (!wdd->ops->get_timeleft)
 		return -EOPNOTSUPP;
 
-	mutex_lock(&wdd->lock);
-
-	if (test_bit(WDOG_UNREGISTERED, &wdd->status)) {
-		err = -ENODEV;
-		goto out_timeleft;
-	}
-
 	*timeleft = wdd->ops->get_timeleft(wdd);
 
-out_timeleft:
-	mutex_unlock(&wdd->lock);
-	return err;
+	return 0;
 }
 
 #ifdef CONFIG_WATCHDOG_SYSFS
@@ -261,14 +228,14 @@ static ssize_t status_show(struct device *dev, struct device_attribute *attr,
 				char *buf)
 {
 	struct watchdog_device *wdd = dev_get_drvdata(dev);
-	ssize_t status;
-	unsigned int val;
+	struct watchdog_core_data *wd_data = wdd->wd_data;
+	unsigned int status;
 
-	status = watchdog_get_status(wdd, &val);
-	if (!status)
-		status = sprintf(buf, "%u\n", val);
+	mutex_lock(&wd_data->lock);
+	status = watchdog_get_status(wdd);
+	mutex_unlock(&wd_data->lock);
 
-	return status;
+	return sprintf(buf, "%u\n", status);
 }
 static DEVICE_ATTR_RO(status);
 
@@ -285,10 +252,13 @@ static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr,
 				char *buf)
 {
 	struct watchdog_device *wdd = dev_get_drvdata(dev);
+	struct watchdog_core_data *wd_data = wdd->wd_data;
 	ssize_t status;
 	unsigned int val;
 
+	mutex_lock(&wd_data->lock);
 	status = watchdog_get_timeleft(wdd, &val);
+	mutex_unlock(&wd_data->lock);
 	if (!status)
 		status = sprintf(buf, "%u\n", val);
 
@@ -365,28 +335,17 @@ __ATTRIBUTE_GROUPS(wdt);
  *	@wdd: the watchdog device to do the ioctl on
  *	@cmd: watchdog command
  *	@arg: argument pointer
+ *
+ *	The caller must hold wd_data->lock.
  */
 
 static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
 							unsigned long arg)
 {
-	int err;
-
 	if (!wdd->ops->ioctl)
 		return -ENOIOCTLCMD;
 
-	mutex_lock(&wdd->lock);
-
-	if (test_bit(WDOG_UNREGISTERED, &wdd->status)) {
-		err = -ENODEV;
-		goto out_ioctl;
-	}
-
-	err = wdd->ops->ioctl(wdd, cmd, arg);
-
-out_ioctl:
-	mutex_unlock(&wdd->lock);
-	return err;
+	return wdd->ops->ioctl(wdd, cmd, arg);
 }
 
 /*
@@ -404,10 +363,11 @@ out_ioctl:
 static ssize_t watchdog_write(struct file *file, const char __user *data,
 						size_t len, loff_t *ppos)
 {
-	struct watchdog_device *wdd = file->private_data;
+	struct watchdog_core_data *wd_data = file->private_data;
+	struct watchdog_device *wdd;
+	int err;
 	size_t i;
 	char c;
-	int err;
 
 	if (len == 0)
 		return 0;
@@ -416,18 +376,25 @@ static ssize_t watchdog_write(struct file *file, const char __user *data,
 	 * Note: just in case someone wrote the magic character
 	 * five months ago...
 	 */
-	clear_bit(WDOG_ALLOW_RELEASE, &wdd->status);
+	clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
 
 	/* scan to see whether or not we got the magic character */
 	for (i = 0; i != len; i++) {
 		if (get_user(c, data + i))
 			return -EFAULT;
 		if (c == 'V')
-			set_bit(WDOG_ALLOW_RELEASE, &wdd->status);
+			set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status);
 	}
 
 	/* someone wrote to us, so we send the watchdog a keepalive ping */
-	err = watchdog_ping(wdd);
+
+	err = -ENODEV;
+	mutex_lock(&wd_data->lock);
+	wdd = wd_data->wdd;
+	if (wdd)
+		err = watchdog_ping(wdd);
+	mutex_unlock(&wd_data->lock);
+
 	if (err < 0)
 		return err;
 
@@ -447,71 +414,94 @@ static ssize_t watchdog_write(struct file *file, const char __user *data,
 static long watchdog_ioctl(struct file *file, unsigned int cmd,
 							unsigned long arg)
 {
-	struct watchdog_device *wdd = file->private_data;
+	struct watchdog_core_data *wd_data = file->private_data;
 	void __user *argp = (void __user *)arg;
+	struct watchdog_device *wdd;
 	int __user *p = argp;
 	unsigned int val;
 	int err;
 
+	mutex_lock(&wd_data->lock);
+
+	wdd = wd_data->wdd;
+	if (!wdd) {
+		err = -ENODEV;
+		goto out_ioctl;
+	}
+
 	err = watchdog_ioctl_op(wdd, cmd, arg);
 	if (err != -ENOIOCTLCMD)
-		return err;
+		goto out_ioctl;
 
 	switch (cmd) {
 	case WDIOC_GETSUPPORT:
-		return copy_to_user(argp, wdd->info,
+		err = copy_to_user(argp, wdd->info,
 			sizeof(struct watchdog_info)) ? -EFAULT : 0;
+		break;
 	case WDIOC_GETSTATUS:
-		err = watchdog_get_status(wdd, &val);
-		if (err == -ENODEV)
-			return err;
-		return put_user(val, p);
+		val = watchdog_get_status(wdd);
+		err = put_user(val, p);
+		break;
 	case WDIOC_GETBOOTSTATUS:
-		return put_user(wdd->bootstatus, p);
+		err = put_user(wdd->bootstatus, p);
+		break;
 	case WDIOC_SETOPTIONS:
-		if (get_user(val, p))
-			return -EFAULT;
+		if (get_user(val, p)) {
+			err = -EFAULT;
+			break;
+		}
 		if (val & WDIOS_DISABLECARD) {
 			err = watchdog_stop(wdd);
 			if (err < 0)
-				return err;
+				break;
 		}
-		if (val & WDIOS_ENABLECARD) {
+		if (val & WDIOS_ENABLECARD)
 			err = watchdog_start(wdd);
-			if (err < 0)
-				return err;
-		}
-		return 0;
+		break;
 	case WDIOC_KEEPALIVE:
-		if (!(wdd->info->options & WDIOF_KEEPALIVEPING))
-			return -EOPNOTSUPP;
-		return watchdog_ping(wdd);
+		if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) {
+			err = -EOPNOTSUPP;
+			break;
+		}
+		err = watchdog_ping(wdd);
+		break;
 	case WDIOC_SETTIMEOUT:
-		if (get_user(val, p))
-			return -EFAULT;
+		if (get_user(val, p)) {
+			err = -EFAULT;
+			break;
+		}
 		err = watchdog_set_timeout(wdd, val);
 		if (err < 0)
-			return err;
+			break;
 		/* If the watchdog is active then we send a keepalive ping
 		 * to make sure that the watchdog keep's running (and if
 		 * possible that it takes the new timeout) */
 		err = watchdog_ping(wdd);
 		if (err < 0)
-			return err;
+			break;
 		/* Fall */
 	case WDIOC_GETTIMEOUT:
 		/* timeout == 0 means that we don't know the timeout */
-		if (wdd->timeout == 0)
-			return -EOPNOTSUPP;
-		return put_user(wdd->timeout, p);
+		if (wdd->timeout == 0) {
+			err = -EOPNOTSUPP;
+			break;
+		}
+		err = put_user(wdd->timeout, p);
+		break;
 	case WDIOC_GETTIMELEFT:
 		err = watchdog_get_timeleft(wdd, &val);
-		if (err)
-			return err;
-		return put_user(val, p);
+		if (err < 0)
+			break;
+		err = put_user(val, p);
+		break;
 	default:
-		return -ENOTTY;
+		err = -ENOTTY;
+		break;
 	}
+
+out_ioctl:
+	mutex_unlock(&wd_data->lock);
+	return err;
 }
 
 /*
@@ -526,45 +516,59 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
 
 static int watchdog_open(struct inode *inode, struct file *file)
 {
-	int err = -EBUSY;
+	struct watchdog_core_data *wd_data;
 	struct watchdog_device *wdd;
+	int err;
 
 	/* Get the corresponding watchdog device */
 	if (imajor(inode) == MISC_MAJOR)
-		wdd = old_wdd;
+		wd_data = old_wd_data;
 	else
-		wdd = container_of(inode->i_cdev, struct watchdog_device, cdev);
+		wd_data = container_of(inode->i_cdev, struct watchdog_core_data,
+				       cdev);
 
 	/* the watchdog is single open! */
-	if (test_and_set_bit(WDOG_DEV_OPEN, &wdd->status))
+	if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status))
 		return -EBUSY;
 
+	wdd = wd_data->wdd;
+
 	/*
 	 * If the /dev/watchdog device is open, we don't want the module
 	 * to be unloaded.
 	 */
-	if (!try_module_get(wdd->ops->owner))
-		goto out;
+	if (!try_module_get(wdd->ops->owner)) {
+		err = -EBUSY;
+		goto out_clear;
+	}
 
 	err = watchdog_start(wdd);
 	if (err < 0)
 		goto out_mod;
 
-	file->private_data = wdd;
+	file->private_data = wd_data;
 
-	if (wdd->ops->ref)
-		wdd->ops->ref(wdd);
+	kref_get(&wd_data->kref);
 
 	/* dev/watchdog is a virtual (and thus non-seekable) filesystem */
 	return nonseekable_open(inode, file);
 
 out_mod:
-	module_put(wdd->ops->owner);
-out:
-	clear_bit(WDOG_DEV_OPEN, &wdd->status);
+	module_put(wd_data->wdd->ops->owner);
+out_clear:
+	clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
 	return err;
 }
 
+static void watchdog_core_data_release(struct kref *kref)
+{
+	struct watchdog_core_data *wd_data;
+
+	wd_data = container_of(kref, struct watchdog_core_data, kref);
+
+	kfree(wd_data);
+}
+
 /*
  *	watchdog_release: release the watchdog device.
  *	@inode: inode of device
@@ -577,9 +581,16 @@ out:
 
 static int watchdog_release(struct inode *inode, struct file *file)
 {
-	struct watchdog_device *wdd = file->private_data;
+	struct watchdog_core_data *wd_data = file->private_data;
+	struct watchdog_device *wdd;
 	int err = -EBUSY;
 
+	mutex_lock(&wd_data->lock);
+
+	wdd = wd_data->wdd;
+	if (!wdd)
+		goto done;
+
 	/*
 	 * We only stop the watchdog if we received the magic character
 	 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
@@ -587,29 +598,24 @@ static int watchdog_release(struct inode *inode, struct file *file)
 	 */
 	if (!test_bit(WDOG_ACTIVE, &wdd->status))
 		err = 0;
-	else if (test_and_clear_bit(WDOG_ALLOW_RELEASE, &wdd->status) ||
+	else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
 		 !(wdd->info->options & WDIOF_MAGICCLOSE))
 		err = watchdog_stop(wdd);
 
 	/* If the watchdog was not stopped, send a keepalive ping */
 	if (err < 0) {
-		mutex_lock(&wdd->lock);
-		if (!test_bit(WDOG_UNREGISTERED, &wdd->status))
-			dev_crit(wdd->dev, "watchdog did not stop!\n");
-		mutex_unlock(&wdd->lock);
+		dev_crit(wdd->dev, "watchdog did not stop!\n");
 		watchdog_ping(wdd);
 	}
 
-	/* Allow the owner module to be unloaded again */
-	module_put(wdd->ops->owner);
-
 	/* make sure that /dev/watchdog can be re-opened */
-	clear_bit(WDOG_DEV_OPEN, &wdd->status);
-
-	/* Note wdd may be gone after this, do not use after this! */
-	if (wdd->ops->unref)
-		wdd->ops->unref(wdd);
+	clear_bit(_WDOG_DEV_OPEN, &wd_data->status);
 
+done:
+	mutex_unlock(&wd_data->lock);
+	/* Allow the owner module to be unloaded again */
+	module_put(wd_data->cdev.owner);
+	kref_put(&wd_data->kref, watchdog_core_data_release);
 	return 0;
 }
 
@@ -639,10 +645,20 @@ static struct miscdevice watchdog_miscdev = {
 
 static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
 {
+	struct watchdog_core_data *wd_data;
 	int err;
 
+	wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL);
+	if (!wd_data)
+		return -ENOMEM;
+	kref_init(&wd_data->kref);
+	mutex_init(&wd_data->lock);
+
+	wd_data->wdd = wdd;
+	wdd->wd_data = wd_data;
+
 	if (wdd->id == 0) {
-		old_wdd = wdd;
+		old_wd_data = wd_data;
 		watchdog_miscdev.parent = wdd->parent;
 		err = misc_register(&watchdog_miscdev);
 		if (err != 0) {
@@ -651,23 +667,25 @@ static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
 			if (err == -EBUSY)
 				pr_err("%s: a legacy watchdog module is probably present.\n",
 					wdd->info->identity);
-			old_wdd = NULL;
+			old_wd_data = NULL;
+			kfree(wd_data);
 			return err;
 		}
 	}
 
 	/* Fill in the data structures */
-	cdev_init(&wdd->cdev, &watchdog_fops);
-	wdd->cdev.owner = wdd->ops->owner;
+	cdev_init(&wd_data->cdev, &watchdog_fops);
+	wd_data->cdev.owner = wdd->ops->owner;
 
 	/* Add the device */
-	err  = cdev_add(&wdd->cdev, devno, 1);
+	err = cdev_add(&wd_data->cdev, devno, 1);
 	if (err) {
 		pr_err("watchdog%d unable to add device %d:%d\n",
 			wdd->id,  MAJOR(watchdog_devt), wdd->id);
 		if (wdd->id == 0) {
 			misc_deregister(&watchdog_miscdev);
-			old_wdd = NULL;
+			old_wd_data = NULL;
+			kref_put(&wd_data->kref, watchdog_core_data_release);
 		}
 	}
 	return err;
@@ -683,15 +701,20 @@ static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno)
 
 static void watchdog_cdev_unregister(struct watchdog_device *wdd)
 {
-	mutex_lock(&wdd->lock);
-	set_bit(WDOG_UNREGISTERED, &wdd->status);
-	mutex_unlock(&wdd->lock);
+	struct watchdog_core_data *wd_data = wdd->wd_data;
 
-	cdev_del(&wdd->cdev);
+	cdev_del(&wd_data->cdev);
 	if (wdd->id == 0) {
 		misc_deregister(&watchdog_miscdev);
-		old_wdd = NULL;
+		old_wd_data = NULL;
 	}
+
+	mutex_lock(&wd_data->lock);
+	wd_data->wdd = NULL;
+	wdd->wd_data = NULL;
+	mutex_unlock(&wd_data->lock);
+
+	kref_put(&wd_data->kref, watchdog_core_data_release);
 }
 
 static struct class watchdog_class = {
@@ -742,9 +765,9 @@ int watchdog_dev_register(struct watchdog_device *wdd)
 
 void watchdog_dev_unregister(struct watchdog_device *wdd)
 {
-	watchdog_cdev_unregister(wdd);
 	device_destroy(&watchdog_class, wdd->dev->devt);
 	wdd->dev = NULL;
+	watchdog_cdev_unregister(wdd);
 }
 
 /*