watchdog: Add multiple device support
We keep the old /dev/watchdog interface file for the first watchdog via miscdev. This is basically a cut and paste of the relevant interface code from the rtc driver layer tweaked for watchdog. Revised to fix problems noted by Hans de Goede Signed-off-by: Alan Cox <alan@linux.intel.com> Signed-off-by: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Tomas Winkler <tomas.winkler@intel.com> Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
This commit is contained in:
Alan Cox
committed by
Wim Van Sebroeck
Wim Van Sebroeck
orang tua
fb5f665816
melakukan
45f5fed30a
@@ -44,10 +44,10 @@
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#include "watchdog_core.h"
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/* make sure we only register one /dev/watchdog device */
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static unsigned long watchdog_dev_busy;
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/* the dev_t structure to store the dynamically allocated watchdog devices */
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static dev_t watchdog_devt;
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/* the watchdog device behind /dev/watchdog */
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static struct watchdog_device *wdd;
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static struct watchdog_device *old_wdd;
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/*
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* watchdog_ping: ping the watchdog.
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@@ -138,6 +138,7 @@ static int watchdog_stop(struct watchdog_device *wddev)
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static ssize_t watchdog_write(struct file *file, const char __user *data,
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size_t len, loff_t *ppos)
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{
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struct watchdog_device *wdd = file->private_data;
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size_t i;
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char c;
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@@ -177,6 +178,7 @@ static ssize_t watchdog_write(struct file *file, const char __user *data,
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static long watchdog_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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struct watchdog_device *wdd = file->private_data;
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void __user *argp = (void __user *)arg;
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int __user *p = argp;
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unsigned int val;
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@@ -249,11 +251,11 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
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}
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/*
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* watchdog_open: open the /dev/watchdog device.
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* watchdog_open: open the /dev/watchdog* devices.
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* @inode: inode of device
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* @file: file handle to device
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*
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* When the /dev/watchdog device gets opened, we start the watchdog.
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* When the /dev/watchdog* device gets opened, we start the watchdog.
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* Watch out: the /dev/watchdog device is single open, so we make sure
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* it can only be opened once.
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*/
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@@ -261,6 +263,13 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
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static int watchdog_open(struct inode *inode, struct file *file)
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{
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int err = -EBUSY;
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struct watchdog_device *wdd;
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/* Get the corresponding watchdog device */
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if (imajor(inode) == MISC_MAJOR)
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wdd = old_wdd;
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else
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wdd = container_of(inode->i_cdev, struct watchdog_device, cdev);
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/* the watchdog is single open! */
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if (test_and_set_bit(WDOG_DEV_OPEN, &wdd->status))
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@@ -277,6 +286,8 @@ static int watchdog_open(struct inode *inode, struct file *file)
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if (err < 0)
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goto out_mod;
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file->private_data = wdd;
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/* dev/watchdog is a virtual (and thus non-seekable) filesystem */
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return nonseekable_open(inode, file);
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@@ -288,9 +299,9 @@ out:
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}
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/*
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* watchdog_release: release the /dev/watchdog device.
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* @inode: inode of device
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* @file: file handle to device
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* watchdog_release: release the watchdog device.
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* @inode: inode of device
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* @file: file handle to device
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*
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* This is the code for when /dev/watchdog gets closed. We will only
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* stop the watchdog when we have received the magic char (and nowayout
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@@ -299,6 +310,7 @@ out:
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static int watchdog_release(struct inode *inode, struct file *file)
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{
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struct watchdog_device *wdd = file->private_data;
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int err = -EBUSY;
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/*
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@@ -340,62 +352,87 @@ static struct miscdevice watchdog_miscdev = {
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};
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/*
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* watchdog_dev_register:
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* watchdog_dev_register: register a watchdog device
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* @watchdog: watchdog device
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*
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* Register a watchdog device as /dev/watchdog. /dev/watchdog
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* is actually a miscdevice and thus we set it up like that.
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* Register a watchdog device including handling the legacy
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* /dev/watchdog node. /dev/watchdog is actually a miscdevice and
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* thus we set it up like that.
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*/
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int watchdog_dev_register(struct watchdog_device *watchdog)
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{
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int err;
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int err, devno;
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/* Only one device can register for /dev/watchdog */
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if (test_and_set_bit(0, &watchdog_dev_busy)) {
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pr_err("only one watchdog can use /dev/watchdog\n");
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return -EBUSY;
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if (watchdog->id == 0) {
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err = misc_register(&watchdog_miscdev);
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if (err != 0) {
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pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n",
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watchdog->info->identity, WATCHDOG_MINOR, err);
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if (err == -EBUSY)
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pr_err("%s: a legacy watchdog module is probably present.\n",
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watchdog->info->identity);
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return err;
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}
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old_wdd = watchdog;
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}
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wdd = watchdog;
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/* Fill in the data structures */
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devno = MKDEV(MAJOR(watchdog_devt), watchdog->id);
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cdev_init(&watchdog->cdev, &watchdog_fops);
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watchdog->cdev.owner = watchdog->ops->owner;
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err = misc_register(&watchdog_miscdev);
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if (err != 0) {
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pr_err("%s: cannot register miscdev on minor=%d (err=%d)\n",
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watchdog->info->identity, WATCHDOG_MINOR, err);
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goto out;
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/* Add the device */
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err = cdev_add(&watchdog->cdev, devno, 1);
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if (err) {
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pr_err("watchdog%d unable to add device %d:%d\n",
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watchdog->id, MAJOR(watchdog_devt), watchdog->id);
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if (watchdog->id == 0) {
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misc_deregister(&watchdog_miscdev);
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old_wdd = NULL;
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}
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}
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return 0;
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out:
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wdd = NULL;
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clear_bit(0, &watchdog_dev_busy);
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return err;
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}
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/*
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* watchdog_dev_unregister:
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* watchdog_dev_unregister: unregister a watchdog device
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* @watchdog: watchdog device
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*
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* Deregister the /dev/watchdog device.
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* Unregister the watchdog and if needed the legacy /dev/watchdog device.
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*/
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int watchdog_dev_unregister(struct watchdog_device *watchdog)
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{
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/* Check that a watchdog device was registered in the past */
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if (!test_bit(0, &watchdog_dev_busy) || !wdd)
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return -ENODEV;
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/* We can only unregister the watchdog device that was registered */
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if (watchdog != wdd) {
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pr_err("%s: watchdog was not registered as /dev/watchdog\n",
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watchdog->info->identity);
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return -ENODEV;
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cdev_del(&watchdog->cdev);
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if (watchdog->id == 0) {
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misc_deregister(&watchdog_miscdev);
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old_wdd = NULL;
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}
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misc_deregister(&watchdog_miscdev);
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wdd = NULL;
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clear_bit(0, &watchdog_dev_busy);
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return 0;
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}
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/*
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* watchdog_dev_init: init dev part of watchdog core
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*
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* Allocate a range of chardev nodes to use for watchdog devices
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*/
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int __init watchdog_dev_init(void)
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{
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int err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog");
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if (err < 0)
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pr_err("watchdog: unable to allocate char dev region\n");
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return err;
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}
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/*
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* watchdog_dev_exit: exit dev part of watchdog core
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*
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* Release the range of chardev nodes used for watchdog devices
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*/
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void __exit watchdog_dev_exit(void)
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{
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unregister_chrdev_region(watchdog_devt, MAX_DOGS);
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}
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