[PATCH] dvb: dst: protect the read/write commands with a mutex

We need to protect the read/write commands with a mutex.

Bug reported by Henrik Sjoberg <henke@epact.se>

Signed-off-by: Manu Abraham <manu@linuxtv.org>
Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Cc: Johannes Stezenbach <js@linuxtv.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/media/dvb/bt8xx/dst_common.h b/drivers/media/dvb/bt8xx/dst_common.h
index 29b5430..81557f3 100644
--- a/drivers/media/dvb/bt8xx/dst_common.h
+++ b/drivers/media/dvb/bt8xx/dst_common.h
@@ -22,6 +22,7 @@
 #ifndef DST_COMMON_H
 #define DST_COMMON_H
 
+#include <linux/smp_lock.h>
 #include <linux/dvb/frontend.h>
 #include <linux/device.h>
 #include "bt878.h"
@@ -119,6 +120,8 @@
 	u8 card_info[8];
 	u8 vendor[8];
 	u8 board_info[8];
+
+	struct semaphore dst_mutex;
 };
 
 struct dst_types {