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

1 files changed, 6 insertions, 5 deletions

diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index 1bcd208c459f..0c053607ce98 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -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;
 }