ded2b66615
Add required locking around idr_ routines, retry the idr_pre_get/idr_get_new pair properly, and sprinkle in some likely/unlikely for good measure. (Lack of idr locking didn't hurt when all callers were I2C clients, as the i2c-core serialized for us anyway. Now that we have non I2C hwmon drivers, this is truly necessary.) Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com> Signed-off-by: Jean Delvare <khali@linux-fr.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
114 lines
2.7 KiB
C
114 lines
2.7 KiB
C
/*
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hwmon.c - part of lm_sensors, Linux kernel modules for hardware monitoring
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This file defines the sysfs class "hwmon", for use by sensors drivers.
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Copyright (C) 2005 Mark M. Hoffman <mhoffman@lightlink.com>
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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 as published by
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the Free Software Foundation; version 2 of the License.
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*/
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#include <linux/module.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/kdev_t.h>
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#include <linux/idr.h>
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#include <linux/hwmon.h>
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#include <linux/gfp.h>
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#include <linux/spinlock.h>
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#define HWMON_ID_PREFIX "hwmon"
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#define HWMON_ID_FORMAT HWMON_ID_PREFIX "%d"
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static struct class *hwmon_class;
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static DEFINE_IDR(hwmon_idr);
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static DEFINE_SPINLOCK(idr_lock);
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/**
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* hwmon_device_register - register w/ hwmon sysfs class
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* @dev: the device to register
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*
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* hwmon_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 class_device *hwmon_device_register(struct device *dev)
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{
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struct class_device *cdev;
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int id, err;
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again:
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if (unlikely(idr_pre_get(&hwmon_idr, GFP_KERNEL) == 0))
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return ERR_PTR(-ENOMEM);
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spin_lock(&idr_lock);
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err = idr_get_new(&hwmon_idr, NULL, &id);
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spin_unlock(&idr_lock);
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if (unlikely(err == -EAGAIN))
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goto again;
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else if (unlikely(err))
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return ERR_PTR(err);
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id = id & MAX_ID_MASK;
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cdev = class_device_create(hwmon_class, NULL, MKDEV(0,0), dev,
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HWMON_ID_FORMAT, id);
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if (IS_ERR(cdev)) {
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spin_lock(&idr_lock);
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idr_remove(&hwmon_idr, id);
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spin_unlock(&idr_lock);
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}
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return cdev;
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}
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/**
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* hwmon_device_unregister - removes the previously registered class device
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*
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* @cdev: the class device to destroy
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*/
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void hwmon_device_unregister(struct class_device *cdev)
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{
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int id;
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if (likely(sscanf(cdev->class_id, HWMON_ID_FORMAT, &id) == 1)) {
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class_device_unregister(cdev);
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spin_lock(&idr_lock);
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idr_remove(&hwmon_idr, id);
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spin_unlock(&idr_lock);
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} else
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dev_dbg(cdev->dev,
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"hwmon_device_unregister() failed: bad class ID!\n");
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}
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static int __init hwmon_init(void)
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{
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hwmon_class = class_create(THIS_MODULE, "hwmon");
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if (IS_ERR(hwmon_class)) {
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printk(KERN_ERR "hwmon.c: couldn't create sysfs class\n");
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return PTR_ERR(hwmon_class);
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}
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return 0;
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}
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static void __exit hwmon_exit(void)
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{
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class_destroy(hwmon_class);
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}
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module_init(hwmon_init);
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module_exit(hwmon_exit);
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EXPORT_SYMBOL_GPL(hwmon_device_register);
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EXPORT_SYMBOL_GPL(hwmon_device_unregister);
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MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
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MODULE_DESCRIPTION("hardware monitoring sysfs/class support");
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MODULE_LICENSE("GPL");
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