drivers/char/misc.c:misc_register(): do not loop on misc_list unconditionally
authorDae S. Kim <dae@velatum.com>
Thu, 28 Feb 2013 01:05:14 +0000 (17:05 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 28 Feb 2013 03:10:21 +0000 (19:10 -0800)
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>
drivers/char/misc.c

index 522136d..190d442 100644 (file)
@@ -183,19 +183,12 @@ static const struct file_operations misc_fops = {
  
 int misc_register(struct miscdevice * misc)
 {
  
 int misc_register(struct miscdevice * misc)
 {
-       struct miscdevice *c;
        dev_t dev;
        int err = 0;
 
        INIT_LIST_HEAD(&misc->list);
 
        mutex_lock(&misc_mtx);
        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);
 
        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);
                }
                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);
        }
 
        dev = MKDEV(MISC_MAJOR, misc->minor);