use mutex instead of semaphore for misc char devices

The misc character device driver uses a semaphore as mutex.  Use the mutex API
instead of the (binary) semaphore.

Signed-off-by: Matthias Kaehlcke <matthias.kaehlcke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 14 insertions, 13 deletions

diff --git a/drivers/char/misc.c b/drivers/char/misc.c
index 7e975f606924..4e6fb9651a16 100644
--- a/drivers/char/misc.c
+++ b/drivers/char/misc.c
@@ -41,6 +41,7 @@
 #include <linux/kernel.h>
 #include <linux/major.h>
 #include <linux/slab.h>
+#include <linux/mutex.h>
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 #include <linux/stat.h>
@@ -53,7 +54,7 @@
  * Head entry for the doubly linked miscdevice list
  */
 static LIST_HEAD(misc_list);
-static DECLARE_MUTEX(misc_sem);
+static DEFINE_MUTEX(misc_mtx);
 
 /*
  * Assigned numbers, used for dynamic minors
@@ -69,7 +70,7 @@ static void *misc_seq_start(struct seq_file *seq, loff_t *pos)
         struct miscdevice *p;
         loff_t off = 0;
 
-        down(&misc_sem);
+        mutex_lock(&misc_mtx);
         list_for_each_entry(p, &misc_list, list) {
                 if (*pos == off++) 
                         return p;
@@ -89,7 +90,7 @@ static void *misc_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 
 static void misc_seq_stop(struct seq_file *seq, void *v)
 {
-        up(&misc_sem);
+        mutex_unlock(&misc_mtx);
 }
 
 static int misc_seq_show(struct seq_file *seq, void *v)
@@ -129,7 +130,7 @@ static int misc_open(struct inode * inode, struct file * file)
         int err = -ENODEV;
         const struct file_operations *old_fops, *new_fops = NULL;
         
-        down(&misc_sem);
+        mutex_lock(&misc_mtx);
         
         list_for_each_entry(c, &misc_list, list) {
                 if (c->minor == minor) {
@@ -139,9 +140,9 @@ static int misc_open(struct inode * inode, struct file * file)
         }
                 
         if (!new_fops) {
-                up(&misc_sem);
+                mutex_unlock(&misc_mtx);
                 request_module("char-major-%d-%d", MISC_MAJOR, minor);
-                down(&misc_sem);
+                mutex_lock(&misc_mtx);
 
                 list_for_each_entry(c, &misc_list, list) {
                         if (c->minor == minor) {
@@ -165,7 +166,7 @@ static int misc_open(struct inode * inode, struct file * file)
         }
         fops_put(old_fops);
 fail:
-        up(&misc_sem);
+        mutex_unlock(&misc_mtx);
         return err;
 }
 
@@ -201,10 +202,10 @@ int misc_register(struct miscdevice * misc)
 
         INIT_LIST_HEAD(&misc->list);
 
-        down(&misc_sem);
+        mutex_lock(&misc_mtx);
         list_for_each_entry(c, &misc_list, list) {
                 if (c->minor == misc->minor) {
-                        up(&misc_sem);
+                        mutex_unlock(&misc_mtx);
                         return -EBUSY;
                 }
         }
@@ -215,7 +216,7 @@ int misc_register(struct miscdevice * misc)
                         if ( (misc_minors[i>>3] & (1 << (i&7))) == 0)
                                 break;
                 if (i<0) {
-                        up(&misc_sem);
+                        mutex_unlock(&misc_mtx);
                         return -EBUSY;
                 }
                 misc->minor = i;
@@ -238,7 +239,7 @@ int misc_register(struct miscdevice * misc)
          */
         list_add(&misc->list, &misc_list);
  out:
-        up(&misc_sem);
+        mutex_unlock(&misc_mtx);
         return err;
 }
 
@@ -259,13 +260,13 @@ int misc_deregister(struct miscdevice * misc)
         if (list_empty(&misc->list))
                 return -EINVAL;
 
-        down(&misc_sem);
+        mutex_lock(&misc_mtx);
         list_del(&misc->list);
         device_destroy(misc_class, MKDEV(MISC_MAJOR, misc->minor));
         if (i < DYNAMIC_MINORS && i>0) {
                 misc_minors[i>>3] &= ~(1 << (misc->minor & 7));
         }
-        up(&misc_sem);
+        mutex_unlock(&misc_mtx);
         return 0;
 }