soundcore_open: Reduce the area BKL coverage

Most of this function is protected by the sound_loader_lock.
We can push down the BKL to this call out err = file->f_op->open(inode,file);

In order to build the sound core without the BKL, we
will need to push the lock_kernel() call into the ~20
device drivers that register their file operations.

Signed-off-by: John Kacur <jkacur@redhat.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/sound_core.c

@@ -576,8 +576,6 @@ static int soundcore_open(struct inode *inode, struct file *file)
 	struct sound_unit *s;
 	const struct file_operations *new_fops = NULL;
 
-	lock_kernel ();
-
 	chain=unit&0x0F;
 	if(chain==4 || chain==5)	/* dsp/audio/dsp16 */
 	{
@@ -630,18 +628,23 @@ static int soundcore_open(struct inode *inode, struct file *file)
 		const struct file_operations *old_fops = file->f_op;
 		file->f_op = new_fops;
 		spin_unlock(&sound_loader_lock);
-		if(file->f_op->open)
+
+		if (file->f_op->open) {
+			/* TODO: push down BKL into indivial open functions */
+			lock_kernel();
 			err = file->f_op->open(inode,file);
+			unlock_kernel();
+		}
+
 		if (err) {
 			fops_put(file->f_op);
 			file->f_op = fops_get(old_fops);
 		}
+
 		fops_put(old_fops);
-		unlock_kernel();
 		return err;
 	}
 	spin_unlock(&sound_loader_lock);
-	unlock_kernel();
 	return -ENODEV;
 }