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Commit ded2b666 authored by Mark M. Hoffman's avatar Mark M. Hoffman Committed by Greg Kroah-Hartman
Browse files

[PATCH] hwmon: add required idr locking 



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: default avatarMark M. Hoffman <mhoffman@lightlink.com>
Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent f6c27fc1

drivers/hwmon/hwmon.c

+20 −6
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <linux/idr.h>

#include <linux/hwmon.h>

#include <linux/gfp.h>

#include <linux/spinlock.h>



#define HWMON_ID_PREFIX "hwmon"

#define HWMON_ID_FORMAT HWMON_ID_PREFIX "%d"
@@ -24,6 +25,7 @@ 
static struct class *hwmon_class;



static DEFINE_IDR(hwmon_idr);

static DEFINE_SPINLOCK(idr_lock);



/**

 * hwmon_device_register - register w/ hwmon sysfs class
@@ -37,20 +39,30 @@ static DEFINE_IDR(hwmon_idr); 
struct class_device *hwmon_device_register(struct device *dev)

{

	struct class_device *cdev;

	int id;

	int id, err;



	if (idr_pre_get(&hwmon_idr, GFP_KERNEL) == 0)

again:

	if (unlikely(idr_pre_get(&hwmon_idr, GFP_KERNEL) == 0))

		return ERR_PTR(-ENOMEM);



	if (idr_get_new(&hwmon_idr, NULL, &id) < 0)

		return ERR_PTR(-ENOMEM);

	spin_lock(&idr_lock);

	err = idr_get_new(&hwmon_idr, NULL, &id);

	spin_unlock(&idr_lock);



	if (unlikely(err == -EAGAIN))

		goto again;

	else if (unlikely(err))

		return ERR_PTR(err);



	id = id & MAX_ID_MASK;

	cdev = class_device_create(hwmon_class, NULL, MKDEV(0,0), dev,

					HWMON_ID_FORMAT, id);



	if (IS_ERR(cdev))

	if (IS_ERR(cdev)) {

		spin_lock(&idr_lock);

		idr_remove(&hwmon_idr, id);

		spin_unlock(&idr_lock);

	}



	return cdev;

}
@@ -64,9 +76,11 @@ void hwmon_device_unregister(struct class_device *cdev) 
{

	int id;



	if (sscanf(cdev->class_id, HWMON_ID_FORMAT, &id) == 1) {

	if (likely(sscanf(cdev->class_id, HWMON_ID_FORMAT, &id) == 1)) {

		class_device_unregister(cdev);

		spin_lock(&idr_lock);

		idr_remove(&hwmon_idr, id);

		spin_unlock(&idr_lock);

	} else

		dev_dbg(cdev->dev,

			"hwmon_device_unregister() failed: bad class ID!\n");