e109ebd1ee
Fix an oops on the rtc_device_unregister() path by waiting until the last moment before nulling the rtc->ops vector. Fix some potential oopses by having the rtc_class_open()/rtc_class_close() interface increase the RTC's reference count while an RTC handle is available outside the RTC framework. Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Cc: Alessandro Zummo <a.zummo@towertech.it> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
156 lines
3.5 KiB
C
156 lines
3.5 KiB
C
/*
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* RTC subsystem, base class
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*
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* Copyright (C) 2005 Tower Technologies
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* Author: Alessandro Zummo <a.zummo@towertech.it>
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*
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* class skeleton from drivers/hwmon/hwmon.c
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/module.h>
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#include <linux/rtc.h>
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#include <linux/kdev_t.h>
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#include <linux/idr.h>
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static DEFINE_IDR(rtc_idr);
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static DEFINE_MUTEX(idr_lock);
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struct class *rtc_class;
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static void rtc_device_release(struct class_device *class_dev)
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{
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struct rtc_device *rtc = to_rtc_device(class_dev);
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mutex_lock(&idr_lock);
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idr_remove(&rtc_idr, rtc->id);
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mutex_unlock(&idr_lock);
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kfree(rtc);
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}
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/**
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* rtc_device_register - register w/ RTC class
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* @dev: the device to register
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*
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* rtc_device_unregister() must be called when the class device is no
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* longer needed.
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*
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* Returns the pointer to the new struct class device.
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*/
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struct rtc_device *rtc_device_register(const char *name, struct device *dev,
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const struct rtc_class_ops *ops,
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struct module *owner)
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{
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struct rtc_device *rtc;
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int id, err;
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if (idr_pre_get(&rtc_idr, GFP_KERNEL) == 0) {
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err = -ENOMEM;
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goto exit;
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}
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mutex_lock(&idr_lock);
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err = idr_get_new(&rtc_idr, NULL, &id);
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mutex_unlock(&idr_lock);
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if (err < 0)
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goto exit;
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id = id & MAX_ID_MASK;
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rtc = kzalloc(sizeof(struct rtc_device), GFP_KERNEL);
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if (rtc == NULL) {
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err = -ENOMEM;
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goto exit_idr;
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}
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rtc->id = id;
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rtc->ops = ops;
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rtc->owner = owner;
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rtc->max_user_freq = 64;
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rtc->class_dev.dev = dev;
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rtc->class_dev.class = rtc_class;
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rtc->class_dev.release = rtc_device_release;
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mutex_init(&rtc->ops_lock);
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spin_lock_init(&rtc->irq_lock);
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spin_lock_init(&rtc->irq_task_lock);
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strlcpy(rtc->name, name, RTC_DEVICE_NAME_SIZE);
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snprintf(rtc->class_dev.class_id, BUS_ID_SIZE, "rtc%d", id);
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err = class_device_register(&rtc->class_dev);
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if (err)
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goto exit_kfree;
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dev_info(dev, "rtc core: registered %s as %s\n",
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rtc->name, rtc->class_dev.class_id);
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return rtc;
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exit_kfree:
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kfree(rtc);
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exit_idr:
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mutex_lock(&idr_lock);
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idr_remove(&rtc_idr, id);
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mutex_unlock(&idr_lock);
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exit:
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dev_err(dev, "rtc core: unable to register %s, err = %d\n",
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name, err);
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return ERR_PTR(err);
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}
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EXPORT_SYMBOL_GPL(rtc_device_register);
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/**
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* rtc_device_unregister - removes the previously registered RTC class device
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*
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* @rtc: the RTC class device to destroy
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*/
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void rtc_device_unregister(struct rtc_device *rtc)
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{
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if (class_device_get(&rtc->class_dev) != NULL) {
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mutex_lock(&rtc->ops_lock);
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/* remove innards of this RTC, then disable it, before
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* letting any rtc_class_open() users access it again
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*/
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class_device_unregister(&rtc->class_dev);
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rtc->ops = NULL;
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mutex_unlock(&rtc->ops_lock);
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class_device_put(&rtc->class_dev);
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}
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}
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EXPORT_SYMBOL_GPL(rtc_device_unregister);
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int rtc_interface_register(struct class_interface *intf)
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{
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intf->class = rtc_class;
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return class_interface_register(intf);
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}
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EXPORT_SYMBOL_GPL(rtc_interface_register);
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static int __init rtc_init(void)
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{
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rtc_class = class_create(THIS_MODULE, "rtc");
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if (IS_ERR(rtc_class)) {
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printk(KERN_ERR "%s: couldn't create class\n", __FILE__);
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return PTR_ERR(rtc_class);
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}
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return 0;
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}
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static void __exit rtc_exit(void)
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{
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class_destroy(rtc_class);
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}
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subsys_initcall(rtc_init);
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module_exit(rtc_exit);
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MODULE_AUTHOR("Alessandro Zummo <a.zummo@towertech.it>");
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MODULE_DESCRIPTION("RTC class support");
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MODULE_LICENSE("GPL");
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