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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>
This commit is contained in:
Matthias Kaehlcke 2007-05-08 00:32:08 -07:00 committed by Linus Torvalds
parent 6acc369a43
commit 0e82d5b618
1 changed files with 14 additions and 13 deletions
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27
drivers/char/misc.c
View File

@ -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;
}