sound: push BKL into open functions

This moves the lock_kernel() call from soundcore_open
to the individual OSS device drivers, where we can deal
with it one driver at a time if needed, or just kill
off the drivers.

All core components in ALSA already provide
adequate locking in their open()-functions
and do not require the big kernel lock, so
there is no need to add the BKL there.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/oss/sh_dac_audio.c b/sound/oss/sh_dac_audio.c
index 4153752..8f0be40 100644
--- a/sound/oss/sh_dac_audio.c
+++ b/sound/oss/sh_dac_audio.c
@@ -16,6 +16,7 @@
 #include <linux/slab.h>
 #include <linux/fs.h>
 #include <linux/sound.h>
+#include <linux/smp_lock.h>
 #include <linux/soundcard.h>
 #include <linux/interrupt.h>
 #include <linux/hrtimer.h>
@@ -216,13 +217,17 @@
 {
 	if (file->f_mode & FMODE_READ)
 		return -ENODEV;
-	if (in_use)
+
+	lock_kernel();
+	if (in_use) {
+		unlock_kernel();
 		return -EBUSY;
+	}
 
 	in_use = 1;
 
 	dac_audio_start();
-
+	unlock_kernel();
 	return 0;
 }