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OpenCloudOS-Kernel
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uml: kill big kernel lock 

Three uml device drivers still use the big kernel lock,
but all of them can be safely converted to using
a per-driver mutex instead. Most likely this is not
even necessary, so after further review these can
and should be removed as well.

The exec system call no longer requires the BKL either,
so remove it from there, too.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: user-mode-linux-devel@lists.sourceforge.net
This commit is contained in:
Arnd Bergmann 2010-09-11 18:38:03 +02:00
parent fa0d4c26be
commit 9a181c5861
4 changed files with 20 additions and 18 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
arch/um/drivers/harddog_kern.c
View File

@ -42,7 +42,7 @@
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/reboot.h>
#include <linux/smp_lock.h>
#include <linux/mutex.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <asm/uaccess.h>
@ -50,6 +50,7 @@
MODULE_LICENSE("GPL");
static DEFINE_MUTEX(harddog_mutex);
static DEFINE_SPINLOCK(lock);
static int timer_alive;
static int harddog_in_fd = -1;
@ -66,7 +67,7 @@ static int harddog_open(struct inode *inode, struct file *file)
int err = -EBUSY;
char *sock = NULL;
lock_kernel();
mutex_lock(&harddog_mutex);
spin_lock(&lock);
if(timer_alive)
goto err;
@ -83,11 +84,11 @@ static int harddog_open(struct inode *inode, struct file *file)
timer_alive = 1;
spin_unlock(&lock);
unlock_kernel();
mutex_unlock(&harddog_mutex);
return nonseekable_open(inode, file);
err:
spin_unlock(&lock);
unlock_kernel();
mutex_unlock(&harddog_mutex);
return err;
}
@ -153,9 +154,9 @@ static long harddog_ioctl(struct file *file,
{
long ret;
lock_kernel();
mutex_lock(&harddog_mutex);
ret = harddog_ioctl_unlocked(file, cmd, arg);
unlock_kernel();
mutex_unlock(&harddog_mutex);
return ret;
}

12
arch/um/drivers/hostaudio_kern.c
View File

@ -8,7 +8,7 @@
#include "linux/slab.h"
#include "linux/sound.h"
#include "linux/soundcard.h"
#include "linux/smp_lock.h"
#include "linux/mutex.h"
#include "asm/uaccess.h"
#include "init.h"
#include "os.h"
@ -67,6 +67,8 @@ MODULE_PARM_DESC(mixer, MIXER_HELP);
#endif
static DEFINE_MUTEX(hostaudio_mutex);
/* /dev/dsp file operations */
static ssize_t hostaudio_read(struct file *file, char __user *buffer,
@ -202,9 +204,9 @@ static int hostaudio_open(struct inode *inode, struct file *file)
w = 1;
kparam_block_sysfs_write(dsp);
lock_kernel();
mutex_lock(&hostaudio_mutex);
ret = os_open_file(dsp, of_set_rw(OPENFLAGS(), r, w), 0);
unlock_kernel();
mutex_unlock(&hostaudio_mutex);
kparam_unblock_sysfs_write(dsp);
if (ret < 0) {
@ -263,9 +265,9 @@ static int hostmixer_open_mixdev(struct inode *inode, struct file *file)
w = 1;
kparam_block_sysfs_write(mixer);
lock_kernel();
mutex_lock(&hostaudio_mutex);
ret = os_open_file(mixer, of_set_rw(OPENFLAGS(), r, w), 0);
unlock_kernel();
mutex_unlock(&hostaudio_mutex);
kparam_unblock_sysfs_write(mixer);
if (ret < 0) {

11
arch/um/drivers/ubd_kern.c
View File

@ -33,7 +33,7 @@
#include "linux/mm.h"
#include "linux/slab.h"
#include "linux/vmalloc.h"
#include "linux/smp_lock.h"
#include "linux/mutex.h"
#include "linux/blkpg.h"
#include "linux/genhd.h"
#include "linux/spinlock.h"
@ -100,6 +100,7 @@ static inline void ubd_set_bit(__u64 bit, unsigned char *data)
#define DRIVER_NAME "uml-blkdev"
static DEFINE_MUTEX(ubd_lock);
static DEFINE_MUTEX(ubd_mutex); /* replaces BKL, might not be needed */
static int ubd_open(struct block_device *bdev, fmode_t mode);
static int ubd_release(struct gendisk *disk, fmode_t mode);
@ -1099,7 +1100,7 @@ static int ubd_open(struct block_device *bdev, fmode_t mode)
struct ubd *ubd_dev = disk->private_data;
int err = 0;
lock_kernel();
mutex_lock(&ubd_mutex);
if(ubd_dev->count == 0){
err = ubd_open_dev(ubd_dev);
if(err){
@ -1118,7 +1119,7 @@ static int ubd_open(struct block_device *bdev, fmode_t mode)
err = -EROFS;
}*/
out:
unlock_kernel();
mutex_unlock(&ubd_mutex);
return err;
}
@ -1126,10 +1127,10 @@ static int ubd_release(struct gendisk *disk, fmode_t mode)
{
struct ubd *ubd_dev = disk->private_data;
lock_kernel();
mutex_lock(&ubd_mutex);
if(--ubd_dev->count == 0)
ubd_close_dev(ubd_dev);
unlock_kernel();
mutex_unlock(&ubd_mutex);
return 0;
}

2
arch/um/kernel/exec.c
View File

@ -78,13 +78,11 @@ long sys_execve(const char __user *file, char __user *__user *argv,
long error;
char *filename;
lock_kernel();
filename = getname(file);
error = PTR_ERR(filename);
if (IS_ERR(filename)) goto out;
error = execve1(filename, argv, env);
putname(filename);
out:
unlock_kernel();
return error;
}