256 lines
6.8 KiB
C
256 lines
6.8 KiB
C
/******************************************************************************
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* Xen balloon driver - enables returning/claiming memory to/from Xen.
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*
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* Copyright (c) 2003, B Dragovic
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* Copyright (c) 2003-2004, M Williamson, K Fraser
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* Copyright (c) 2005 Dan M. Smith, IBM Corporation
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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 version 2
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* as published by the Free Software Foundation; or, when distributed
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* separately from the Linux kernel or incorporated into other
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* software packages, subject to the following license:
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this source file (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy, modify,
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* merge, publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/mm_types.h>
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#include <linux/init.h>
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#include <linux/capability.h>
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#include <xen/xen.h>
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#include <xen/interface/xen.h>
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#include <xen/balloon.h>
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#include <xen/xenbus.h>
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#include <xen/features.h>
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#include <xen/page.h>
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#define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))
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#define BALLOON_CLASS_NAME "xen_memory"
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static struct device balloon_dev;
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static int register_balloon(struct device *dev);
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/* React to a change in the target key */
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static void watch_target(struct xenbus_watch *watch,
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const char *path, const char *token)
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{
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unsigned long long new_target, static_max;
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int err;
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static bool watch_fired;
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static long target_diff;
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err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target);
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if (err != 1) {
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/* This is ok (for domain0 at least) - so just return */
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return;
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}
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/* The given memory/target value is in KiB, so it needs converting to
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* pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10.
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*/
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new_target >>= PAGE_SHIFT - 10;
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if (!watch_fired) {
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watch_fired = true;
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err = xenbus_scanf(XBT_NIL, "memory", "static-max", "%llu",
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&static_max);
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if (err != 1)
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static_max = new_target;
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else
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static_max >>= PAGE_SHIFT - 10;
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target_diff = xen_pv_domain() ? 0
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: static_max - balloon_stats.target_pages;
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}
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balloon_set_new_target(new_target - target_diff);
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}
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static struct xenbus_watch target_watch = {
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.node = "memory/target",
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.callback = watch_target,
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};
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static int balloon_init_watcher(struct notifier_block *notifier,
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unsigned long event,
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void *data)
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{
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int err;
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err = register_xenbus_watch(&target_watch);
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if (err)
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pr_err("Failed to set balloon watcher\n");
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return NOTIFY_DONE;
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}
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static struct notifier_block xenstore_notifier = {
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.notifier_call = balloon_init_watcher,
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};
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void xen_balloon_init(void)
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{
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register_balloon(&balloon_dev);
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register_xen_selfballooning(&balloon_dev);
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register_xenstore_notifier(&xenstore_notifier);
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}
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EXPORT_SYMBOL_GPL(xen_balloon_init);
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#define BALLOON_SHOW(name, format, args...) \
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static ssize_t show_##name(struct device *dev, \
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struct device_attribute *attr, \
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char *buf) \
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{ \
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return sprintf(buf, format, ##args); \
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} \
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static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
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BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages));
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BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low));
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BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high));
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static DEVICE_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay);
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static DEVICE_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay);
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static DEVICE_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count);
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static DEVICE_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count);
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static ssize_t show_target_kb(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages));
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}
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static ssize_t store_target_kb(struct device *dev,
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struct device_attribute *attr,
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const char *buf,
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size_t count)
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{
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char *endchar;
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unsigned long long target_bytes;
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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target_bytes = simple_strtoull(buf, &endchar, 0) * 1024;
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balloon_set_new_target(target_bytes >> PAGE_SHIFT);
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return count;
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}
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static DEVICE_ATTR(target_kb, S_IRUGO | S_IWUSR,
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show_target_kb, store_target_kb);
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static ssize_t show_target(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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return sprintf(buf, "%llu\n",
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(unsigned long long)balloon_stats.target_pages
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<< PAGE_SHIFT);
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}
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static ssize_t store_target(struct device *dev,
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struct device_attribute *attr,
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const char *buf,
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size_t count)
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{
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char *endchar;
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unsigned long long target_bytes;
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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target_bytes = memparse(buf, &endchar);
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balloon_set_new_target(target_bytes >> PAGE_SHIFT);
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return count;
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}
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static DEVICE_ATTR(target, S_IRUGO | S_IWUSR,
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show_target, store_target);
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static struct attribute *balloon_attrs[] = {
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&dev_attr_target_kb.attr,
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&dev_attr_target.attr,
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&dev_attr_schedule_delay.attr.attr,
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&dev_attr_max_schedule_delay.attr.attr,
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&dev_attr_retry_count.attr.attr,
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&dev_attr_max_retry_count.attr.attr,
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NULL
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};
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static const struct attribute_group balloon_group = {
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.attrs = balloon_attrs
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};
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static struct attribute *balloon_info_attrs[] = {
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&dev_attr_current_kb.attr,
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&dev_attr_low_kb.attr,
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&dev_attr_high_kb.attr,
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NULL
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};
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static const struct attribute_group balloon_info_group = {
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.name = "info",
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.attrs = balloon_info_attrs
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};
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static const struct attribute_group *balloon_groups[] = {
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&balloon_group,
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&balloon_info_group,
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NULL
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};
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static struct bus_type balloon_subsys = {
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.name = BALLOON_CLASS_NAME,
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.dev_name = BALLOON_CLASS_NAME,
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};
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static int register_balloon(struct device *dev)
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{
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int error;
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error = subsys_system_register(&balloon_subsys, NULL);
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if (error)
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return error;
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dev->id = 0;
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dev->bus = &balloon_subsys;
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dev->groups = balloon_groups;
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error = device_register(dev);
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if (error) {
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bus_unregister(&balloon_subsys);
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return error;
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}
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return 0;
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}
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