From: Dae S. Kim <dae@velatum.com>
Date: Thu, 28 Feb 2013 01:05:14 +0000 (-0800)
Subject: drivers/char/misc.c:misc_register(): do not loop on misc_list unconditionally
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=3c94ce6f48f484bbc4dba83c0ed1f98f5e10957c;p=deliverable%2Flinux.git

drivers/char/misc.c:misc_register(): do not loop on misc_list unconditionally

If the minor number is assigned dynamically, there is no need to search
for misc->minor in misc_list, since misc->minor == MISC_DYNAMIC_MINOR.

[akpm@linux-foundation.org: reduce scope of local `c']
Signed-off-by: Dae S. Kim <dae@velatum.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/drivers/char/misc.c b/drivers/char/misc.c
index 522136d40843..190d4423653f 100644
--- a/drivers/char/misc.c
+++ b/drivers/char/misc.c
@@ -183,19 +183,12 @@ static const struct file_operations misc_fops = {
  
 int misc_register(struct miscdevice * misc)
 {
-	struct miscdevice *c;
 	dev_t dev;
 	int err = 0;
 
 	INIT_LIST_HEAD(&misc->list);
 
 	mutex_lock(&misc_mtx);
-	list_for_each_entry(c, &misc_list, list) {
-		if (c->minor == misc->minor) {
-			mutex_unlock(&misc_mtx);
-			return -EBUSY;
-		}
-	}
 
 	if (misc->minor == MISC_DYNAMIC_MINOR) {
 		int i = find_first_zero_bit(misc_minors, DYNAMIC_MINORS);
@@ -205,6 +198,15 @@ int misc_register(struct miscdevice * misc)
 		}
 		misc->minor = DYNAMIC_MINORS - i - 1;
 		set_bit(i, misc_minors);
+	} else {
+		struct miscdevice *c;
+
+		list_for_each_entry(c, &misc_list, list) {
+			if (c->minor == misc->minor) {
+				mutex_unlock(&misc_mtx);
+				return -EBUSY;
+			}
+		}
 	}
 
 	dev = MKDEV(MISC_MAJOR, misc->minor);