From 3040724f532cef78f5733243dbc26f2ff4cc4f12 Mon Sep 17 00:00:00 2001
From: "Mark M. Hoffman" <mhoffman@lightlink.com>
Date: Sun, 5 Mar 2006 23:13:47 +0100
Subject: [PATCH] --- yaml --- r: 23263 b: refs/heads/master c:
 ded2b66615613093eeb83b81499bc270de8fc499 h: refs/heads/master i:   23261:
 816c5374ca16ce83a2251c2409c04d739a0c4b81   23259:
 e6009d0c67a0a4148c0b86c973045c9838b19df1   23255:
 cea1935e4c95d28670a08ee41a453ced6095fac7   23247:
 45487e3fcd07aa3dafa96cf479e48e749f8ed1bd   23231:
 ecfeadef76c5581b09913d85c896fa321b511a37 v: v3

---
 [refs]                      |  2 +-
 trunk/drivers/hwmon/hwmon.c | 26 ++++++++++++++++++++------
 2 files changed, 21 insertions(+), 7 deletions(-)

diff --git a/[refs] b/[refs]
index 060105979ebd..d43a72eaba25 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f6c27fc17c5e575c5471fb344bdbd5f5f6072136
+refs/heads/master: ded2b66615613093eeb83b81499bc270de8fc499
diff --git a/trunk/drivers/hwmon/hwmon.c b/trunk/drivers/hwmon/hwmon.c
index dddd3eb9b387..106fa01cdb60 100644
--- a/trunk/drivers/hwmon/hwmon.c
+++ b/trunk/drivers/hwmon/hwmon.c
@@ -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");