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>

diff --git a/drivers/char/misc.c b/drivers/char/misc.c
index 7e975f6..4e6fb96 100644 (file)
--- 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;
 }